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1. Performance and first measurements of the MAGIC Stellar Intensity Interferometer

Author: MAGIC Collaboration, Abe, S., Abhir, J., Acciari, V. A., Aguasca-Cabot, A., Agudo, I., Aniello, T., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Arcaro, C., Artero, M., Asano, K., Babić, A., Baquero, A., de Almeida, U. Barres, Barrio, J. A., Batković, I., Bautista, A., Baxter, J., González, J. Becerra, Bernardini, E., Bernardos, M., Bernete, J., Berti, A., Besenrieder, J., Bigongiari, C., Biland, A., Blanch, O., Bošnjak, Ž., Burelli, I., Busetto, G., Campoy-Ordaz, A., Carosi, A., Carosi, R., Carretero-Castrillo, M., Ceribella, G., Chai, Y., Cifuentes, A., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., de Menezes, R., Del Popolo, A., Delfino, M., Delgado, J., Mendez, C. Delgado, Di Pierro, F., Di Venere, L., Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Emery, G., Escudero, J., na, L. Fari, Fattorini, A., Foffano, L., Font, L., Fröse, S., Fukami, S., Fukazawa, Y., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Paiva, J. G. Giesbrecht, Giglietto, N., Giordano, F., Gliwny, P., Gradetzke, T., Grau, R., Green, D., Green, J. G., Günther, P., Hadasch, D., Hahn, A., Hassan, T., Heckmann, L., Herrera, J., Hrupec, D., Hütten, M., Imazawa, R., Ishio, K., Martínez, I. Jiménez, Jormanainen, J., Kayanoki, T., Kerszberg, D., Kluge, G. W., Kobayashi, Y., Kouch, P. M., Kubo, H., Kushida, J., Láinez, M., Lamastra, A., Leone, F., Lindfors, E., Linhoff, L., Lombardi, S., Longo, F., López-Coto, R., López-Moya, M., López-Oramas, A., Loporchio, S., Lorini, A., Lyard, E., Fraga, B. Machado de Oliveira, Majumdar, P., Makariev, M., Maneva, G., Mang, N., Manganaro, M., Mangano, S., Mannheim, K., Mariotti, M., Martínez, M., Martínez-Chicharro, M., Mas-Aguilar, A., Mazin, D., Menchiari, S., Mender, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., González, M. Molero, Molina, E., Mondal, H. A., Moralejo, A., Morcuende, D., Nakamori, T., Nanci, C., Neustroev, V., Nickel, L., Rosillo, M. Nievas, Nigro, C., Nikolić, L., Nilsson, K., Nishijima, K., Ekoume, T. Njoh, Noda, K., Nozaki, S., Ohtani, Y., Okumura, A., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Peresano, M., Persic, M., Pihet, M., Pirola, G., Podobnik, F., Moroni, P. G. Prada, Prandini, E., Principe, G., Priyadarshi, C., Rhode, W., Ribó, M., Rico, J., Righi, C., Sahakyan, N., Saito, T., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schmuckermaier, F., Schubert, J. L., Schweizer, T., Sciaccaluga, A., Silvestri, G., Sitarek, J., Sliusar, V., Sobczynska, D., Spolon, A., Stamerra, A., Strišković, J., Strom, D., Strzys, M., Suda, Y., Surić, T., Suutarinen, S., Tajima, H., Takahashi, M., Takeishi, R., Temnikov, P., Terauchi, K., Terzić, T., Truzzi, M. Teshima S., Tutone, A., Ubach, S., van Scherpenberg, J., Acosta, M. Vazquez, Ventura, S., Viale, I., Vigorito, C. F., Vitale, V., Walter, R., Will, M., Wunderlich, C., Yamamoto, T., Díaz, G. Chon C., Fiori, M., Lobo, M., Naletto, G., Polo, M., Rodríguez-Vázquez, J. J., Saha, P., Zampieri, L., MAGIC Collaboration, Abe, S., Abhir, J., Acciari, V. A., Aguasca-Cabot, A., Agudo, I., Aniello, T., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Arcaro, C., Artero, M., Asano, K., Babić, A., Baquero, A., de Almeida, U. Barres, Barrio, J. A., Batković, I., Bautista, A., Baxter, J., González, J. Becerra, Bernardini, E., Bernardos, M., Bernete, J., Berti, A., Besenrieder, J., Bigongiari, C., Biland, A., Blanch, O., Bošnjak, Ž., Burelli, I., Busetto, G., Campoy-Ordaz, A., Carosi, A., Carosi, R., Carretero-Castrillo, M., Ceribella, G., Chai, Y., Cifuentes, A., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., de Menezes, R., Del Popolo, A., Delfino, M., Delgado, J., Mendez, C. Delgado, Di Pierro, F., Di Venere, L., Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Emery, G., Escudero, J., na, L. Fari, Fattorini, A., Foffano, L., Font, L., Fröse, S., Fukami, S., Fukazawa, Y., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Paiva, J. G. Giesbrecht, Giglietto, N., Giordano, F., Gliwny, P., Gradetzke, T., Grau, R., Green, D., Green, J. G., Günther, P., Hadasch, D., Hahn, A., Hassan, T., Heckmann, L., Herrera, J., Hrupec, D., Hütten, M., Imazawa, R., Ishio, K., Martínez, I. Jiménez, Jormanainen, J., Kayanoki, T., Kerszberg, D., Kluge, G. W., Kobayashi, Y., Kouch, P. M., Kubo, H., Kushida, J., Láinez, M., Lamastra, A., Leone, F., Lindfors, E., Linhoff, L., Lombardi, S., Longo, F., López-Coto, R., López-Moya, M., López-Oramas, A., Loporchio, S., Lorini, A., Lyard, E., Fraga, B. Machado de Oliveira, Majumdar, P., Makariev, M., Maneva, G., Mang, N., Manganaro, M., Mangano, S., Mannheim, K., Mariotti, M., Martínez, M., Martínez-Chicharro, M., Mas-Aguilar, A., Mazin, D., Menchiari, S., Mender, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., González, M. Molero, Molina, E., Mondal, H. A., Moralejo, A., Morcuende, D., Nakamori, T., Nanci, C., Neustroev, V., Nickel, L., Rosillo, M. Nievas, Nigro, C., Nikolić, L., Nilsson, K., Nishijima, K., Ekoume, T. Njoh, Noda, K., Nozaki, S., Ohtani, Y., Okumura, A., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Peresano, M., Persic, M., Pihet, M., Pirola, G., Podobnik, F., Moroni, P. G. Prada, Prandini, E., Principe, G., Priyadarshi, C., Rhode, W., Ribó, M., Rico, J., Righi, C., Sahakyan, N., Saito, T., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schmuckermaier, F., Schubert, J. L., Schweizer, T., Sciaccaluga, A., Silvestri, G., Sitarek, J., Sliusar, V., Sobczynska, D., Spolon, A., Stamerra, A., Strišković, J., Strom, D., Strzys, M., Suda, Y., Surić, T., Suutarinen, S., Tajima, H., Takahashi, M., Takeishi, R., Temnikov, P., Terauchi, K., Terzić, T., Truzzi, M. Teshima S., Tutone, A., Ubach, S., van Scherpenberg, J., Acosta, M. Vazquez, Ventura, S., Viale, I., Vigorito, C. F., Vitale, V., Walter, R., Will, M., Wunderlich, C., Yamamoto, T., Díaz, G. Chon C., Fiori, M., Lobo, M., Naletto, G., Polo, M., Rodríguez-Vázquez, J. J., Saha, P., and Zampieri, L.
Abstract: In recent years, a new generation of optical intensity interferometers has emerged, leveraging the existing infrastructure of Imaging Atmospheric Cherenkov Telescopes (IACTs). The MAGIC telescopes host the MAGIC-SII system (Stellar Intensity Interferometer), implemented to investigate the feasibility and potential of this technique on IACTs. After the first successful measurements in 2019, the system was upgraded and now features a real-time, dead-time-free, 4-channel, GPU-based correlator. These hardware modifications allow seamless transitions between MAGIC's standard very-high-energy gamma-ray observations and optical interferometry measurements within seconds. We establish the feasibility and potential of employing IACTs as competitive optical Intensity Interferometers with minimal hardware adjustments. The measurement of a total of 22 stellar diameters are reported, 9 corresponding to reference stars with previous comparable measurements, and 13 with no prior measurements. A prospective implementation involving telescopes from the forthcoming Cherenkov Telescope Array Observatory's northern hemisphere array, such as the first prototype of its Large-Sized Telescopes, LST-1, is technically viable. This integration would significantly enhance the sensitivity of the current system and broaden the UV-plane coverage. This advancement would enable the system to achieve competitive sensitivity with the current generation of long-baseline optical interferometers over blue wavelengths., Comment: 18 pages, 13 figures, submitted to MNRAS
Published: 2024
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2. Does Turbulence along the Coronal Current Sheet Drive Ion Cyclotron Waves?

Author: Telloni, Daniele, Zank, Gary P. P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D. D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, Slemer, Alessandra, Telloni, Daniele, Zank, Gary P. P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D. D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, and Slemer, Alessandra
Abstract: Evidence for the presence of ion cyclotron waves (ICWs), driven by turbulence, at the boundaries of the current sheet is reported in this paper. By exploiting the full potential of the joint observations performed by Parker Solar Probe and the Metis coronagraph on board Solar Orbiter, local measurements of the solar wind can be linked with the large-scale structures of the solar corona. The results suggest that the dynamics of the current sheet layers generates turbulence, which in turn creates a sufficiently strong temperature anisotropy to make the solar-wind plasma unstable to anisotropy-driven instabilities such as the Alfven ion cyclotron, mirror-mode, and firehose instabilities. The study of the polarization state of high-frequency magnetic fluctuations reveals that ICWs are indeed present along the current sheet, thus linking the magnetic topology of the remotely imaged coronal source regions with the wave bursts observed in situ. The present results may allow improvement of state-of-the-art models based on the ion cyclotron mechanism, providing new insights into the processes involved in coronal heating.
Published: 2023
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3. Does Turbulence along the Coronal Current Sheet Drive Ion Cyclotron Waves?

Author: Telloni, Daniele, Zank, Gary P. P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D. D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, Slemer, Alessandra, Telloni, Daniele, Zank, Gary P. P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D. D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, and Slemer, Alessandra
Abstract: Evidence for the presence of ion cyclotron waves (ICWs), driven by turbulence, at the boundaries of the current sheet is reported in this paper. By exploiting the full potential of the joint observations performed by Parker Solar Probe and the Metis coronagraph on board Solar Orbiter, local measurements of the solar wind can be linked with the large-scale structures of the solar corona. The results suggest that the dynamics of the current sheet layers generates turbulence, which in turn creates a sufficiently strong temperature anisotropy to make the solar-wind plasma unstable to anisotropy-driven instabilities such as the Alfven ion cyclotron, mirror-mode, and firehose instabilities. The study of the polarization state of high-frequency magnetic fluctuations reveals that ICWs are indeed present along the current sheet, thus linking the magnetic topology of the remotely imaged coronal source regions with the wave bursts observed in situ. The present results may allow improvement of state-of-the-art models based on the ion cyclotron mechanism, providing new insights into the processes involved in coronal heating.
Published: 2023
Full Text: View/download PDF

4. Does Turbulence along the Coronal Current Sheet Drive Ion Cyclotron Waves?

Author: Telloni, Daniele, Zank, Gary P. P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D. D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, Slemer, Alessandra, Telloni, Daniele, Zank, Gary P. P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D. D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, and Slemer, Alessandra
Abstract: Evidence for the presence of ion cyclotron waves (ICWs), driven by turbulence, at the boundaries of the current sheet is reported in this paper. By exploiting the full potential of the joint observations performed by Parker Solar Probe and the Metis coronagraph on board Solar Orbiter, local measurements of the solar wind can be linked with the large-scale structures of the solar corona. The results suggest that the dynamics of the current sheet layers generates turbulence, which in turn creates a sufficiently strong temperature anisotropy to make the solar-wind plasma unstable to anisotropy-driven instabilities such as the Alfven ion cyclotron, mirror-mode, and firehose instabilities. The study of the polarization state of high-frequency magnetic fluctuations reveals that ICWs are indeed present along the current sheet, thus linking the magnetic topology of the remotely imaged coronal source regions with the wave bursts observed in situ. The present results may allow improvement of state-of-the-art models based on the ion cyclotron mechanism, providing new insights into the processes involved in coronal heating.
Published: 2023
Full Text: View/download PDF

5. Does Turbulence along the Coronal Current Sheet Drive Ion Cyclotron Waves?

Author: Telloni, Daniele, Zank, Gary P. P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D. D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, Slemer, Alessandra, Telloni, Daniele, Zank, Gary P. P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D. D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, and Slemer, Alessandra
Abstract: Evidence for the presence of ion cyclotron waves (ICWs), driven by turbulence, at the boundaries of the current sheet is reported in this paper. By exploiting the full potential of the joint observations performed by Parker Solar Probe and the Metis coronagraph on board Solar Orbiter, local measurements of the solar wind can be linked with the large-scale structures of the solar corona. The results suggest that the dynamics of the current sheet layers generates turbulence, which in turn creates a sufficiently strong temperature anisotropy to make the solar-wind plasma unstable to anisotropy-driven instabilities such as the Alfven ion cyclotron, mirror-mode, and firehose instabilities. The study of the polarization state of high-frequency magnetic fluctuations reveals that ICWs are indeed present along the current sheet, thus linking the magnetic topology of the remotely imaged coronal source regions with the wave bursts observed in situ. The present results may allow improvement of state-of-the-art models based on the ion cyclotron mechanism, providing new insights into the processes involved in coronal heating.
Published: 2023
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6. Closing gaps to our origins

Author: Gómez de Castro, Ana Inés, Barstow, Martin A., Baudin, Frederic, Benetti, Stefano, Bouret, Jean Claude, Brosch, Noah, Canet Varea, Ada, Martino, Domitilla de, Zanna, Giulio del, Evans, Chris, France, Kevin, García, Miriam, Gaensicke, Boris, Hillenbrand, Lynne, Josselin, Eric, Kehrig, Carolina, Lamy, Laurent, Lapington, Jon, Etangs, Alain Lecavelier des, Naletto, Giampiero, Nazé, Yael, Neiner, Coralie, Nichols, Jonathan, Orio, Marina, Pagano, Isabella, Peroux, Céline, Rauw, Gregor, Shore, Steven, Tovmassian, Gagik, ud-Doula, Asif, Gómez de Castro, Ana Inés, Barstow, Martin A., Baudin, Frederic, Benetti, Stefano, Bouret, Jean Claude, Brosch, Noah, Canet Varea, Ada, Martino, Domitilla de, Zanna, Giulio del, Evans, Chris, France, Kevin, García, Miriam, Gaensicke, Boris, Hillenbrand, Lynne, Josselin, Eric, Kehrig, Carolina, Lamy, Laurent, Lapington, Jon, Etangs, Alain Lecavelier des, Naletto, Giampiero, Nazé, Yael, Neiner, Coralie, Nichols, Jonathan, Orio, Marina, Pagano, Isabella, Peroux, Céline, Rauw, Gregor, Shore, Steven, Tovmassian, Gagik, and ud-Doula, Asif
Abstract: CRUE-CSIC (Acuerdos Transformativos 2022), This article reproduces the contents of the White Paper entitled by the same name submitted to the call issued by the European Space Agency soliciting ideas from the scientific community for the science themes that should be covered during the Voyage 2050 planning cycle. This contribution focus in the investigation of the emergence of life and the role that astronomy has to play in it. Three fundamental areas of activity are identified: [1] measuring the chemical enrichment of the Universe, [2] investigating planet formation and searching for exoplanets with signatures of life and, [3] determining the abundance of amino acids and the chemical routes to aminoacid and protein growth in astronomical bodies. This proposal deals with the first two. The building blocks of life in the Universe began as primordial gas processed in stars and mixed at galactic scales. The mechanisms responsible for this development are not well-understood and have changed over the intervening 13 billion years. To follow the evolution of matter over cosmic time, it is necessary to study the strongest (resonance) transitions of the most abundant species in the Universe. Most of them are in the ultraviolet (UV; 950 Å - 3000 Å ) spectral range that is unobservable from the ground; the “missing” metals problem cannot be addressed without this access. Habitable planets grow in protostellar discs under ultraviolet irradiation, a by-product of the accretion process that drives the physical and chemical evolution of discs and young planetary systems. The electronic transitions of the most abundant molecules are pumped by this UV field that is the main oxidizing agent in the disc chemistry and provides unique diagnostics of the planet-forming environment that cannot be accessed from the ground. Knowledge of the variability of the UV radiation field is required for the astrochemical modelling of protoplanetary discs, to understand the formation of planetary atmospheres and the photochemistry of the prec, Unidad Deptal. de Astronomía y Geodesia, Fac. de Ciencias Matemáticas, TRUE, pub
Published: 2023

7. Particle monitoring capability of the Solar Orbiter Metis coronagraph through the increasing phase of solar cycle 25

Author: Grimani, Catia, Andretta, Vincenzo, Antonucci, Ester, Chioetto, Paolo, Da Deppo, Vania, Fabi, Michele, Gissot, Samuel, Jerse, Giovanna, Messerotti, Mauro, Naletto, Giampiero, Pancrazzi, Maurizio, Persici, Andrea, Plainaki, Christina, Romoli, Marco, Sabbatini, Federico, Spadaro, Daniele, Stangalini, Marco, Telloni, Daniele, Teriaca, Luca, Uslenghi, Michela, Villani, Mattia, Abbo, Lucia, Burtovoi, Aleksandr, Frassati, Federica, Landini, Federico, Nicolini, Giana, Russano, Giuliana, Sasso, Clementina, Susino, Roberto, Grimani, Catia, Andretta, Vincenzo, Antonucci, Ester, Chioetto, Paolo, Da Deppo, Vania, Fabi, Michele, Gissot, Samuel, Jerse, Giovanna, Messerotti, Mauro, Naletto, Giampiero, Pancrazzi, Maurizio, Persici, Andrea, Plainaki, Christina, Romoli, Marco, Sabbatini, Federico, Spadaro, Daniele, Stangalini, Marco, Telloni, Daniele, Teriaca, Luca, Uslenghi, Michela, Villani, Mattia, Abbo, Lucia, Burtovoi, Aleksandr, Frassati, Federica, Landini, Federico, Nicolini, Giana, Russano, Giuliana, Sasso, Clementina, and Susino, Roberto
Abstract: Context. Galactic cosmic rays (GCRs) and solar particles with energies greater than tens of MeV penetrate spacecraft and instruments hosted aboard space missions. The Solar Orbiter Metis coronagraph is aimed at observing the solar corona in both visible (VL) and ultraviolet (UV) light. Particle tracks are observed in the Metis images of the corona. An algorithm has been implemented in the Metis processing electronics to detect the VL image pixels crossed by cosmic rays. This algorithm was initially enabled for the VL instrument only, since the process of separating the particle tracks in the UV images has proven to be very challenging. Aims. We study the impact of the overall bulk of particles of galactic and solar origin on the Metis coronagraph images. We discuss the effects of the increasing solar activity after the Solar Orbiter mission launch on the secondary particle production in the spacecraft. Methods. We compared Monte Carlo simulations of GCRs crossing or interacting in the Metis VL CMOS sensor to observations gathered in 2020 and 2022. We also evaluated the impact of solar energetic particle events of different intensities on the Metis images. Results. The study of the role of abundant and rare cosmic rays in firing pixels in the Metis VL images of the corona allows us to estimate the efficiency of the algorithm applied for cosmic-ray track removal from the images and to demonstrate that the instrument performance had remained unchanged during the first two years of the Solar Orbiter operations. The outcome of this work can be used to estimate the Solar Orbiter instrument's deep charging and the order of magnitude for energetic particles crossing the images of Metis and other instruments such as STIX and EUI., Comment: 8 pages, 6 figures
Published: 2023
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8. Particle monitoring capability of the Solar Orbiter Metis coronagraph through the increasing phase of solar cycle 25

Author: Grimani, Catia, Andretta, Vincenzo, Antonucci, Ester, Chioetto, Paolo, Da Deppo, Vania, Fabi, Michele, Gissot, Samuel, Jerse, Giovanna, Messerotti, Mauro, Naletto, Giampiero, Pancrazzi, Maurizio, Persici, Andrea, Plainaki, Christina, Romoli, Marco, Sabbatini, Federico, Spadaro, Daniele, Stangalini, Marco, Telloni, Daniele, Teriaca, Luca, Uslenghi, Michela, Villani, Mattia, Abbo, Lucia, Burtovoi, Aleksandr, Frassati, Federica, Landini, Federico, Nicolini, Giana, Russano, Giuliana, Sasso, Clementina, Susino, Roberto, Grimani, Catia, Andretta, Vincenzo, Antonucci, Ester, Chioetto, Paolo, Da Deppo, Vania, Fabi, Michele, Gissot, Samuel, Jerse, Giovanna, Messerotti, Mauro, Naletto, Giampiero, Pancrazzi, Maurizio, Persici, Andrea, Plainaki, Christina, Romoli, Marco, Sabbatini, Federico, Spadaro, Daniele, Stangalini, Marco, Telloni, Daniele, Teriaca, Luca, Uslenghi, Michela, Villani, Mattia, Abbo, Lucia, Burtovoi, Aleksandr, Frassati, Federica, Landini, Federico, Nicolini, Giana, Russano, Giuliana, Sasso, Clementina, and Susino, Roberto
Abstract: Context. Galactic cosmic rays (GCRs) and solar particles with energies greater than tens of MeV penetrate spacecraft and instruments hosted aboard space missions. The Solar Orbiter Metis coronagraph is aimed at observing the solar corona in both visible (VL) and ultraviolet (UV) light. Particle tracks are observed in the Metis images of the corona. An algorithm has been implemented in the Metis processing electronics to detect the VL image pixels crossed by cosmic rays. This algorithm was initially enabled for the VL instrument only, since the process of separating the particle tracks in the UV images has proven to be very challenging. Aims. We study the impact of the overall bulk of particles of galactic and solar origin on the Metis coronagraph images. We discuss the effects of the increasing solar activity after the Solar Orbiter mission launch on the secondary particle production in the spacecraft. Methods. We compared Monte Carlo simulations of GCRs crossing or interacting in the Metis VL CMOS sensor to observations gathered in 2020 and 2022. We also evaluated the impact of solar energetic particle events of different intensities on the Metis images. Results. The study of the role of abundant and rare cosmic rays in firing pixels in the Metis VL images of the corona allows us to estimate the efficiency of the algorithm applied for cosmic-ray track removal from the images and to demonstrate that the instrument performance had remained unchanged during the first two years of the Solar Orbiter operations. The outcome of this work can be used to estimate the Solar Orbiter instrument's deep charging and the order of magnitude for energetic particles crossing the images of Metis and other instruments such as STIX and EUI., Comment: 8 pages, 6 figures
Published: 2023
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9. Coronal Heating Rate in the Slow Solar Wind

Author: Telloni, Daniele, Romoli, Marco, Velli, Marco, Zank, Gary P., Adhikari, Laxman, Downs, Cooper, Burtovoi, Aleksandr, Susino, Roberto, Spadaro, Daniele, Zhao, Lingling, Liberatore, Alessandro, Shi, Chen, De Leo, Yara, Abbo, Lucia, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Nicolini, Gianalfredo, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Grimani, Catia, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Stangalini, Marco, Teriaca, Luca, Uslenghi, Michela, Berlicki, Arkadiusz, Bruno, Roberto, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., D'Amicis, Raffaella, Fabi, Michele, Frassetto, Fabio, Giarrusso, Marina, Giordano, Silvio, Guglielmino, Salvo L., Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Nisticò, Giuseppe, Pelizzo, Maria G., Reale, Fabio, Romano, Paolo, Schühle, Udo, Solanki, Sami K., Straus, Thomas, Ventura, Rita, Volpicelli, Cosimo A., Zangrilli, Luca, Zimbardo, Gaetano, Zuppella, Paola, Bale, Stuart D., Kasper, Justin C., Telloni, Daniele, Romoli, Marco, Velli, Marco, Zank, Gary P., Adhikari, Laxman, Downs, Cooper, Burtovoi, Aleksandr, Susino, Roberto, Spadaro, Daniele, Zhao, Lingling, Liberatore, Alessandro, Shi, Chen, De Leo, Yara, Abbo, Lucia, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Nicolini, Gianalfredo, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Grimani, Catia, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Stangalini, Marco, Teriaca, Luca, Uslenghi, Michela, Berlicki, Arkadiusz, Bruno, Roberto, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., D'Amicis, Raffaella, Fabi, Michele, Frassetto, Fabio, Giarrusso, Marina, Giordano, Silvio, Guglielmino, Salvo L., Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Nisticò, Giuseppe, Pelizzo, Maria G., Reale, Fabio, Romano, Paolo, Schühle, Udo, Solanki, Sami K., Straus, Thomas, Ventura, Rita, Volpicelli, Cosimo A., Zangrilli, Luca, Zimbardo, Gaetano, Zuppella, Paola, Bale, Stuart D., and Kasper, Justin C.
Abstract: This Letter reports the first observational estimate of the heating rate in the slowly expanding solar corona. The analysis exploits the simultaneous remote and local observations of the same coronal plasma volume with the Solar Orbiter/Metis and the Parker Solar Probe instruments, respectively, and relies on the basic solar wind magnetohydrodynamic equations. As expected, energy losses are a minor fraction of the solar wind energy flux, since most of the energy dissipation that feeds the heating and acceleration of the coronal flow occurs much closer to the Sun than the heights probed in the present study, which range from 6.3 to 13.3 solar radii. The energy deposited to the supersonic wind is then used to explain the observed slight residual wind acceleration and to maintain the plasma in a non-adiabatic state. As derived in the Wentzel-Kramers-Brillouin limit, the present energy transfer rate estimates provide a lower limit, which can be very useful in refining the turbulence-based modeling of coronal heating and subsequent solar wind acceleration.
Published: 2023

10. Simultaneous and panchromatic observations of the Fast Radio Burst FRB 20180916B

Author: Trudu, M., Pilia, M., Nicastro, L., Guidorzi, C., Orlandini, M., Zampieri, L., Marthi, V. R., Ambrosino, F., Possenti, A., Burgay, M., Casentini, C., Mereminskiy, I., Savchenko, V., Palazzi, E., Panessa, F., Ridolfi, A., Verrecchia, F., Anedda, M., Bernardi, G., Bachetti, M., Burenin, R., Burtovoi, A., Casella, P., Fiori, M., Frontera, F., Gajjar, V., Gardini, A., Ge, M., Guijarro-Román, A., Ghedina, A., Hermelo, I., Jia, S., Li, C., Liao, J., Li, X., Lu, F., Lutivinov, A., Naletto, G., Ochener, P., Papitto, A., Perri, M., Pittori, C., Safanov, B., Semena, A., Strakhov, I., Tavani, M., Ursi, A., Xiong, S. L., Zhang, S. N., Zheltoukhov, S., Trudu, M., Pilia, M., Nicastro, L., Guidorzi, C., Orlandini, M., Zampieri, L., Marthi, V. R., Ambrosino, F., Possenti, A., Burgay, M., Casentini, C., Mereminskiy, I., Savchenko, V., Palazzi, E., Panessa, F., Ridolfi, A., Verrecchia, F., Anedda, M., Bernardi, G., Bachetti, M., Burenin, R., Burtovoi, A., Casella, P., Fiori, M., Frontera, F., Gajjar, V., Gardini, A., Ge, M., Guijarro-Román, A., Ghedina, A., Hermelo, I., Jia, S., Li, C., Liao, J., Li, X., Lu, F., Lutivinov, A., Naletto, G., Ochener, P., Papitto, A., Perri, M., Pittori, C., Safanov, B., Semena, A., Strakhov, I., Tavani, M., Ursi, A., Xiong, S. L., Zhang, S. N., and Zheltoukhov, S.
Abstract: Aims. Fast Radio Bursts are bright radio transients whose origin has not yet explained. The search for a multi-wavelength counterpart of those events can put a tight constrain on the emission mechanism and the progenitor source. Methods. We conducted a multi-wavelength observational campaign on FRB 20180916B between October 2020 and August 2021 during eight activity cycles of the source. Observations were led in the radio band by the SRT both at 336 MHz and 1547 MHz and the uGMRT at 400 MHz. Simultaneous observations have been conducted by the optical telescopes Asiago (Galileo and Copernico), CMO SAI MSU, CAHA 2.2m, RTT-150 and TNG, and X/Gamma-ray detectors on board the AGILE, Insight-HXMT, INTEGRAL and Swift satellites. Results. We present the detection of 14 new bursts detected with the SRT at 336 MHz and seven new bursts with the uGMRT from this source. We provide the deepest prompt upper limits in the optical band fro FRB 20180916B to date. In fact, the TNG/SiFAP2 observation simultaneous to a burst detection by uGMRT gives an upper limit E_optical / E_radio < 1.3 x 10^2. Another burst detected by the SRT at 336 MHz was also co-observed by Insight-HMXT. The non-detection in the X-rays yields an upper limit (1-30 keV band) of E_X-ray / E_radio in the range of (0.9-1.3) x 10^7, depending on which model is considered for the X-ray emission., Comment: A&A accepted
Published: 2023
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11. Does Turbulence along the Coronal Current Sheet Drive Ion Cyclotron Waves?

Author: Telloni, Daniele, Zank, Gary P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, Slemer, Alessandra, Telloni, Daniele, Zank, Gary P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, and Slemer, Alessandra
Abstract: Evidence for the presence of ion cyclotron waves, driven by turbulence, at the boundaries of the current sheet is reported in this paper. By exploiting the full potential of the joint observations performed by Parker Solar Probe and the Metis coronagraph on board Solar Orbiter, local measurements of the solar wind can be linked with the large-scale structures of the solar corona. The results suggest that the dynamics of the current sheet layers generates turbulence, which in turn creates a sufficiently strong temperature anisotropy to make the solar-wind plasma unstable to anisotropy-driven instabilities such as the Alfv\'en ion-cyclotron, mirror-mode, and firehose instabilities. The study of the polarization state of high-frequency magnetic fluctuations reveals that ion cyclotron waves are indeed present along the current sheet, thus linking the magnetic topology of the remotely imaged coronal source regions with the wave bursts observed in situ. The present results may allow improvement of state-of-the-art models based on the ion cyclotron mechanism, providing new insights into the processes involved in coronal heating., Comment: 12 pages
Published: 2023
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12. Slow wind belt in the quiet solar corona

Author: Antonucci, E., Downs, C., Capuano, G. E., Spadaro, D., Susino, R., Telloni, D., Andretta, V., Da Deppo, V., De Leo, Y., Fineschi, S., Frassetto, F., Landini, F., Naletto, G., Nicolini, G., Pancrazzi, M., Romoli, M., Stangalini, M., Teriaca, L., Uslenghi, M., Antonucci, E., Downs, C., Capuano, G. E., Spadaro, D., Susino, R., Telloni, D., Andretta, V., Da Deppo, V., De Leo, Y., Fineschi, S., Frassetto, F., Landini, F., Naletto, G., Nicolini, G., Pancrazzi, M., Romoli, M., Stangalini, M., Teriaca, L., and Uslenghi, M.
Abstract: The slow solar wind belt in the quiet corona, observed with the Metis coronagraph on board Solar Orbiter on May 15, 2020, during the activity minimum of the cycle 24, in a field of view extending from 3.8 $R_\odot$ to 7.0 $R_\odot$, is formed by a slow and dense wind stream running along the coronal current sheet, accelerating in the radial direction and reaching at 6.8 $R_\odot$ a speed within 150 km s$^{-1}$ and 190 km s$^{-1}$, depending on the assumptions on the velocity distribution of the neutral hydrogen atoms in the coronal plasma. The slow stream is separated by thin regions of high velocity shear from faster streams, almost symmetric relative to the current sheet, with peak velocity within 175 km s$^{-1}$ and 230 km s$^{-1}$ at the same coronal level. The density-velocity structure of the slow wind zone is discussed in terms of the expansion factor of the open magnetic field lines that is known to be related to the speed of the quasi-steady solar wind, and in relation to the presence of a web of quasi separatrix layers, S-web, the potential sites of reconnection that release coronal plasma into the wind. The parameters characterizing the coronal magnetic field lines are derived from 3D MHD model calculations. The S-web is found to coincide with the latitudinal region where the slow wind is observed in the outer corona and is surrounded by thin layers of open field lines expanding in a non-monotonic way.
Published: 2023
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13. In-flight validation of Metis Visible-light Polarimeter Coronagraph on board Solar Orbiter

Author: Liberatore, A., Fineschi, S., Casti, M., Capobianco, G., Abbo, L., Andretta, V., Da Deppo, V., Fabi, M., Frassati, F., Jerse, G., Landini, F., Moses, D., Naletto, G., Nicolini, G., Pancrazzi, M., Romoli, M., Russano, G., Sasso, C., Spadaro, D., Stangalini, M., Susino, R., Telloni, D., Teriaca, L., Uslenghi, M., Liberatore, A., Fineschi, S., Casti, M., Capobianco, G., Abbo, L., Andretta, V., Da Deppo, V., Fabi, M., Frassati, F., Jerse, G., Landini, F., Moses, D., Naletto, G., Nicolini, G., Pancrazzi, M., Romoli, M., Russano, G., Sasso, C., Spadaro, D., Stangalini, M., Susino, R., Telloni, D., Teriaca, L., and Uslenghi, M.
Abstract: Context. The Metis coronagraph is one of the remote-sensing instruments of the ESA/NASA Solar Orbiter mission. Metis is aimed at the study of the solar atmosphere and solar wind by simultaneously acquiring images of the solar corona at two different wavelengths; visible-light (VL) within a band ranging from 580 nm to 640 nm, and in the HI Ly-alpha 121.6 +/- 10 nm ultraviolet (UV) light. The visible-light channel includes a polarimeter with electro-optically modulating Liquid Crystal Variable Retarders (LCVRs) to measure the linearly polarized brightness of the K-corona to derive the electron density. Aims. In this paper, we present the first in-flight validation results of the Metis polarimetric channel together with a comparison to the on-ground calibrations. It is the validation of the first use in deep space (with hard radiation environment) of an electro-optical device: a liquid crystal-based polarimeter. Methods. We used the orientation of the K-corona's linear polarization vector during the spacecraft roll maneuvers for the in-flight calibration. Results. The first in-flight validation of the Metis coronagraph on-board Solar Orbiter shows a good agreement with the on-ground measurements. It confirms the expected visible-light channel polarimetric performance. A final comparison between the first pB obtained by Metis with the polarized brightness (pB) obtained by the space-based coronagraph LASCO and the ground-based coronagraph KCor shows the consistency of the Metis calibrated results., Comment: 8 pages, 13 figures, 3 tables, paper
Published: 2023
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14. Does Turbulence along the Coronal Current Sheet Drive Ion Cyclotron Waves?

Author: Telloni, Daniele, Zank, Gary P. P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D. D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, Slemer, Alessandra, Telloni, Daniele, Zank, Gary P. P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D. D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, and Slemer, Alessandra
Abstract: Evidence for the presence of ion cyclotron waves (ICWs), driven by turbulence, at the boundaries of the current sheet is reported in this paper. By exploiting the full potential of the joint observations performed by Parker Solar Probe and the Metis coronagraph on board Solar Orbiter, local measurements of the solar wind can be linked with the large-scale structures of the solar corona. The results suggest that the dynamics of the current sheet layers generates turbulence, which in turn creates a sufficiently strong temperature anisotropy to make the solar-wind plasma unstable to anisotropy-driven instabilities such as the Alfven ion cyclotron, mirror-mode, and firehose instabilities. The study of the polarization state of high-frequency magnetic fluctuations reveals that ICWs are indeed present along the current sheet, thus linking the magnetic topology of the remotely imaged coronal source regions with the wave bursts observed in situ. The present results may allow improvement of state-of-the-art models based on the ion cyclotron mechanism, providing new insights into the processes involved in coronal heating.
Published: 2023
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15. Eruptive events with exceptionally bright emission in HI Ly-alpha observed by the Metis coronagraph

Author: Russano, G., Andretta, V., De Leo, Y., Teriaca, L., Uslenghi, M., Giordano, S., Telloni, D., Heinzel, P., č, S. Jej či, Abbo, L., Bemporad, A., Burtovoi, A., Capuano, G. E., Frassati, F., Guglielmino, S., Jerse, G., Landini, F., Liberatore, A., Nicolini, G., Pancrazzi, M., Romano, P., Sasso, C., Susino, R., Zangrilli, L., Da Deppo, V., Fineschi, S., Grimani, C., Moses, J. D., Naletto, G., Romoli, M., Spadaro, D., Stangalini, M., Russano, G., Andretta, V., De Leo, Y., Teriaca, L., Uslenghi, M., Giordano, S., Telloni, D., Heinzel, P., č, S. Jej či, Abbo, L., Bemporad, A., Burtovoi, A., Capuano, G. E., Frassati, F., Guglielmino, S., Jerse, G., Landini, F., Liberatore, A., Nicolini, G., Pancrazzi, M., Romano, P., Sasso, C., Susino, R., Zangrilli, L., Da Deppo, V., Fineschi, S., Grimani, C., Moses, J. D., Naletto, G., Romoli, M., Spadaro, D., and Stangalini, M.
Abstract: Metis, the coronagraph on board Solar Orbiter, provides for the first time coronagraphic imaging in the ultraviolet HI Ly-alpha line and, simultaneously, in polarized visible light, thus providing a host of information on the properties of CMEs and solar eruptions like their overall dynamics, time evolution, mass content, and outflow propagation velocity in the expanding corona. We analyzed in this work six CMEs observed by Metis between April and October 2021, which are characterized by a very strong HI Ly-alpha emission. We studied in particular the morphology, kinematics, and the temporal and radial evolution of the emission of such events, focusing on the brightest UV features. The kinematics of the eruptive events under consideration were studied by determining the height-time profiles of the brightest parts on the Metis plane of the sky. Furthermore, the 3D position in the heliosphere of the CMEs were determined by employing co-temporal images from two other coronagraphs: LASCO/C2 onboard SOHO, and COR2 onboard STEREO-A. Finally, the radiometrically calibrated Metis images of the bright UV features were analyzed to provide estimates of their volume and density. From the kinematics and radiometric analyses, we obtained indications of the temperatures of the bright UV cores of these events. The analysis of these strong UV-emitting features associated with coronal mass ejections demonstrates the capabilities of the current constellation of space coronagraphs, Metis, LASCO/C2, and COR2, in providing a complete characterization of the structure and dynamics of eruptive events in their propagation phase from their inception up to several solar radii. Furthermore, we show how the unique capabilities of the Metis instrument to observe these events in both HI Ly-alpha line and polarized VL radiation allow plasma diagnostics on the thermal state of these events., Comment: 26 pages, 26 figures, 2 appendices
Published: 2023

16. A Coronal Mass Ejection followed by a prominence eruption and a plasma blob as observed by Solar Orbiter

Author: Bemporad, A., Andretta, V., Susino, R., Mancuso, S., Spadaro, D., Mierla, M., Berghmans, D., D'Huys, E., Zhukov, A. N., Talpeanu, D. -C., Colaninno, R., Hess, P., Koza, J., Jejcic, S., Heinzel, P., Antonucci, E., Da Deppo, V., Fineschi, S., Frassati, F., Jerse, G., Landini, F., Naletto, G., Nicolini, G., Pancrazzi, M., Romoli, M., Sasso, C., Slemer, A., Stangalini, M., Teriaca, L., Bemporad, A., Andretta, V., Susino, R., Mancuso, S., Spadaro, D., Mierla, M., Berghmans, D., D'Huys, E., Zhukov, A. N., Talpeanu, D. -C., Colaninno, R., Hess, P., Koza, J., Jejcic, S., Heinzel, P., Antonucci, E., Da Deppo, V., Fineschi, S., Frassati, F., Jerse, G., Landini, F., Naletto, G., Nicolini, G., Pancrazzi, M., Romoli, M., Sasso, C., Slemer, A., Stangalini, M., and Teriaca, L.
Abstract: On February 12, 2021 two subsequent eruptions occurred above the West limb, as seen along the Sun-Earth line. The first event was a typical slow Coronal Mass Ejection (CME), followed $\sim 7$ hours later by a smaller and collimated prominence eruption, originating Southward with respect to the CME, followed by a plasma blob. These events were observed not only by SOHO and STEREO-A missions, but also by the suite of remote sensing instruments on-board Solar Orbiter (SolO). This work shows how data acquired by the Full Sun Imager (FSI), Metis coronagraph, and Heliospheric Imager (SoloHI) from the SolO perspective can be combined to study the eruptions and the different source regions. Moreover, we show how Metis data can be analyzed to provide new information about solar eruptions. Different 3D reconstruction methods were applied to the data acquired by different spacecraft including remote sensing instruments on-board SolO. Images acquired by both Metis channels in the Visible Light (VL) and H I Lyman$-\alpha$ line (UV) were combined to derive physical information on the expanding plasma. The polarization ratio technique was also applied for the first time to the Metis images acquired in the VL channel. The two eruptions were followed in 3D from their source region to their expansion in the intermediate corona. Thanks to the combination of VL and UV Metis data, the formation of a post-CME Current Sheet (CS) was followed for the first time in the intermediate corona. The plasma temperature gradient across a post-CME blob propagating along the CS was also measured for the first time. Application of the polarization ratio technique to Metis data shows that, thanks to the combination of four different polarization measurements, the errors are reduced by $\sim 5-7$\%, thus better constraining the 3D distribution of plasma., Comment: 15 pages, 14 figures, accepted for publication on A&A
Published: 2022

17. Deep upper limit on the optical emission during a hard X-ray burst from the magnetar SGR J1935+2154

Author: Zampieri, Luca, Mereghetti, Sandro, Turolla, Roberto, Naletto, Giampiero, Ochner, Paolo, Burtovoi, Aleksandr, Fiori, Michele, Guidorzi, Cristiano, Nicastro, Luciano, Palazzi, Eliana, Pilia, Maura, Possenti, Andrea, Zampieri, Luca, Mereghetti, Sandro, Turolla, Roberto, Naletto, Giampiero, Ochner, Paolo, Burtovoi, Aleksandr, Fiori, Michele, Guidorzi, Cristiano, Nicastro, Luciano, Palazzi, Eliana, Pilia, Maura, and Possenti, Andrea
Abstract: In September 2021 the magnetar SGR J1935+2154 entered a stage of burst/flaring activity in the hard X-ray band. On September 10, 2021 we observed SGR J1935+2154 with the fiber-fed fast optical photon counter IFI+Iqueye, mounted at the 1.22 m Galileo telescope in Asiago. During one of the IFI+Iqueye observing windows a hard X-ray burst was detected with the Fermi Gamma-ray Burst Monitor. We performed a search for any significant increase in the count rate on the 1-s, 10-ms and 1-ms binned IFI+Iqueye light curves around the time of the Fermi burst. No significant peak was detected with a significance above 3$\sigma$ in an interval of $\pm$90 s around the burst. Correcting for interstellar extinction ($A_V \simeq 5.8$ mag), the IFI+Iqueye upper limits to any possible optical burst from SGR J1935+2154 are $V=10.1$ mag, $V=7.2$ mag and $V=5.8$ mag for the 1-s, 10-ms and 1-ms binned light curves, respectively. The corresponding extinction corrected upper limits to the fluence (specific fluence) are $3.1 \times 10^{-10}$ erg cm$^{-2}$ (0.35 Jy s), $4.2 \times 10^{-11}$ erg cm$^{-2}$ (4.8 Jy $\cdot$ 10 ms), and $1.6 \times 10^{-11}$ erg cm$^{-2}$ (17.9 Jy ms), orders of magnitude deeper than any previous simultaneous optical limit on a magnetar burst. The IFI+Iqueye measurement can also place a more stringent constraint to the spectral index of the optical to hard X-ray fluence of SGR J1935+2154, implying a spectrum steeper than $\nu^{0.64}$. Fast optical timing observations of bursts associated with radio emission have then the potential to yield a detection., Comment: 8 pages, 4 figures, accepted for publication in The Astrophysical Journal Letters
Published: 2022
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18. Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar Orbiter Observations

Author: Telloni, Daniele, Zank, Gary P., Sorriso-Valvo, Luca, D'Amicis, Raffaella, Panasenco, Olga, Susino, Roberto, Bruno, Roberto, Perrone, Denise, Adhikari, Laxman, Liang, Haoming, Nakanotani, Masaru, Zhao, Lingling, Hadid, Lina Z., Sanchez-Cano, Beatriz, Verscharen, Daniel, Velli, Marco, Grimani, Catia, Marino, Raffaele, Carbone, Francesco, Mancuso, Salvatore, Biondo, Ruggero, Pagano, Paolo, Reale, Fabio, Bale, Stuart D., Kasper, Justin C., Case, Anthony W., de Wit, Thierry Dudok, Goetz, Keith, Harvey, Peter R., Korreck, Kelly E., Larson, Davin, Livi, Roberto, MacDowall, Robert J., Malaspina, David M., Pulupa, Marc, Stevens, Michael L., Whittlesey, Phyllis, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., De Leo, Yara, Fabi, Michele, Frassati, Federica, Frassetto, Fabio, Giordano, Silvio, Guglielmino, Salvo L., Jerse, Giovanna, Landini, Federico, Liberatore, Alessandro, Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Pancrazzi, Maurizio, Pelizzo, Maria G., Romano, Paolo, Sasso, Clementina, Schuhle, Udo, Slemer, Alessandra, Straus, Thomas, Uslenghi, Michela, Volpicelli, Cosimo A., Zangrilli, Luca, Zuppella, Paola, Abbo, Lucia, Auchere, Frederic, Cuadrado, Regina Aznar, Berlicki, Arkadiusz, Ciaravella, Angela, Lamy, Philippe, Lanzafame, Alessandro, Malvezzi, Marco, Nicolosi, Piergiorgio, Nistico, Giuseppe, Peter, Hardi, Solanki, Sami K., Strachan, Leonard, Tsinganos, Kanaris, Ventura, Rita, Vial, Jean-Claude, Woch, Joachim, Zimbardo, Gaetano, Telloni, Daniele, Zank, Gary P., Sorriso-Valvo, Luca, D'Amicis, Raffaella, Panasenco, Olga, Susino, Roberto, Bruno, Roberto, Perrone, Denise, Adhikari, Laxman, Liang, Haoming, Nakanotani, Masaru, Zhao, Lingling, Hadid, Lina Z., Sanchez-Cano, Beatriz, Verscharen, Daniel, Velli, Marco, Grimani, Catia, Marino, Raffaele, Carbone, Francesco, Mancuso, Salvatore, Biondo, Ruggero, Pagano, Paolo, Reale, Fabio, Bale, Stuart D., Kasper, Justin C., Case, Anthony W., de Wit, Thierry Dudok, Goetz, Keith, Harvey, Peter R., Korreck, Kelly E., Larson, Davin, Livi, Roberto, MacDowall, Robert J., Malaspina, David M., Pulupa, Marc, Stevens, Michael L., Whittlesey, Phyllis, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., De Leo, Yara, Fabi, Michele, Frassati, Federica, Frassetto, Fabio, Giordano, Silvio, Guglielmino, Salvo L., Jerse, Giovanna, Landini, Federico, Liberatore, Alessandro, Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Pancrazzi, Maurizio, Pelizzo, Maria G., Romano, Paolo, Sasso, Clementina, Schuhle, Udo, Slemer, Alessandra, Straus, Thomas, Uslenghi, Michela, Volpicelli, Cosimo A., Zangrilli, Luca, Zuppella, Paola, Abbo, Lucia, Auchere, Frederic, Cuadrado, Regina Aznar, Berlicki, Arkadiusz, Ciaravella, Angela, Lamy, Philippe, Lanzafame, Alessandro, Malvezzi, Marco, Nicolosi, Piergiorgio, Nistico, Giuseppe, Peter, Hardi, Solanki, Sami K., Strachan, Leonard, Tsinganos, Kanaris, Ventura, Rita, Vial, Jean-Claude, Woch, Joachim, and Zimbardo, Gaetano
Abstract: The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R (circle dot) above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local properties of the two streams are different. Specifically, the solar wind emanating from the stronger magnetic field region has a lower bulk flux density, as expected, and is in a state of well-developed Alfvenic turbulence, with low intermittency. This is interpreted in terms of slab turbulence in the context of nearly incompressible magnetohydrodynamics. Conversely, the highly intermittent and poorly developed turbulent behavior of the solar wind from the weaker magnetic field region is presumably due to large magnetic deflections most likely attributed to the presence of switchbacks of interchange reconnection origin.
Published: 2022
Full Text: View/download PDF

19. Observation of a Magnetic Switchback in the Solar Corona

Author: Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Biondo, Ruggero, Burtovoi, Aleksandr, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, De Leo, Yara, Giarrusso, Marina, Liberatore, Alessandro, Berghmans, David, Auchere, Frederic, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, Zhukov, Andrei N., Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Biondo, Ruggero, Burtovoi, Aleksandr, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, De Leo, Yara, Giarrusso, Marina, Liberatore, Alessandro, Berghmans, David, Auchere, Frederic, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, and Zhukov, Andrei N.
Abstract: Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks' formation mechanism and sources are still unresolved, although candidate mechanisms include Alfvenic turbulence, shear-driven Kelvin-Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph on board a Solar Orbiter of a single large propagating S-shaped vortex, interpreted as the first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the east and west. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind.
Published: 2022
Full Text: View/download PDF

20. Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar Orbiter Observations

Author: Telloni, Daniele, Zank, Gary P., Sorriso-Valvo, Luca, D'Amicis, Raffaella, Panasenco, Olga, Susino, Roberto, Bruno, Roberto, Perrone, Denise, Adhikari, Laxman, Liang, Haoming, Nakanotani, Masaru, Zhao, Lingling, Hadid, Lina Z., Sanchez-Cano, Beatriz, Verscharen, Daniel, Velli, Marco, Grimani, Catia, Marino, Raffaele, Carbone, Francesco, Mancuso, Salvatore, Biondo, Ruggero, Pagano, Paolo, Reale, Fabio, Bale, Stuart D., Kasper, Justin C., Case, Anthony W., de Wit, Thierry Dudok, Goetz, Keith, Harvey, Peter R., Korreck, Kelly E., Larson, Davin, Livi, Roberto, MacDowall, Robert J., Malaspina, David M., Pulupa, Marc, Stevens, Michael L., Whittlesey, Phyllis, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., De Leo, Yara, Fabi, Michele, Frassati, Federica, Frassetto, Fabio, Giordano, Silvio, Guglielmino, Salvo L., Jerse, Giovanna, Landini, Federico, Liberatore, Alessandro, Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Pancrazzi, Maurizio, Pelizzo, Maria G., Romano, Paolo, Sasso, Clementina, Schuhle, Udo, Slemer, Alessandra, Straus, Thomas, Uslenghi, Michela, Volpicelli, Cosimo A., Zangrilli, Luca, Zuppella, Paola, Abbo, Lucia, Auchere, Frederic, Cuadrado, Regina Aznar, Berlicki, Arkadiusz, Ciaravella, Angela, Lamy, Philippe, Lanzafame, Alessandro, Malvezzi, Marco, Nicolosi, Piergiorgio, Nistico, Giuseppe, Peter, Hardi, Solanki, Sami K., Strachan, Leonard, Tsinganos, Kanaris, Ventura, Rita, Vial, Jean-Claude, Woch, Joachim, Zimbardo, Gaetano, Telloni, Daniele, Zank, Gary P., Sorriso-Valvo, Luca, D'Amicis, Raffaella, Panasenco, Olga, Susino, Roberto, Bruno, Roberto, Perrone, Denise, Adhikari, Laxman, Liang, Haoming, Nakanotani, Masaru, Zhao, Lingling, Hadid, Lina Z., Sanchez-Cano, Beatriz, Verscharen, Daniel, Velli, Marco, Grimani, Catia, Marino, Raffaele, Carbone, Francesco, Mancuso, Salvatore, Biondo, Ruggero, Pagano, Paolo, Reale, Fabio, Bale, Stuart D., Kasper, Justin C., Case, Anthony W., de Wit, Thierry Dudok, Goetz, Keith, Harvey, Peter R., Korreck, Kelly E., Larson, Davin, Livi, Roberto, MacDowall, Robert J., Malaspina, David M., Pulupa, Marc, Stevens, Michael L., Whittlesey, Phyllis, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., De Leo, Yara, Fabi, Michele, Frassati, Federica, Frassetto, Fabio, Giordano, Silvio, Guglielmino, Salvo L., Jerse, Giovanna, Landini, Federico, Liberatore, Alessandro, Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Pancrazzi, Maurizio, Pelizzo, Maria G., Romano, Paolo, Sasso, Clementina, Schuhle, Udo, Slemer, Alessandra, Straus, Thomas, Uslenghi, Michela, Volpicelli, Cosimo A., Zangrilli, Luca, Zuppella, Paola, Abbo, Lucia, Auchere, Frederic, Cuadrado, Regina Aznar, Berlicki, Arkadiusz, Ciaravella, Angela, Lamy, Philippe, Lanzafame, Alessandro, Malvezzi, Marco, Nicolosi, Piergiorgio, Nistico, Giuseppe, Peter, Hardi, Solanki, Sami K., Strachan, Leonard, Tsinganos, Kanaris, Ventura, Rita, Vial, Jean-Claude, Woch, Joachim, and Zimbardo, Gaetano
Abstract: The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R (circle dot) above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local properties of the two streams are different. Specifically, the solar wind emanating from the stronger magnetic field region has a lower bulk flux density, as expected, and is in a state of well-developed Alfvenic turbulence, with low intermittency. This is interpreted in terms of slab turbulence in the context of nearly incompressible magnetohydrodynamics. Conversely, the highly intermittent and poorly developed turbulent behavior of the solar wind from the weaker magnetic field region is presumably due to large magnetic deflections most likely attributed to the presence of switchbacks of interchange reconnection origin.
Published: 2022
Full Text: View/download PDF

21. Observation of a Magnetic Switchback in the Solar Corona

Author: Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Biondo, Ruggero, Burtovoi, Aleksandr, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, De Leo, Yara, Giarrusso, Marina, Liberatore, Alessandro, Berghmans, David, Auchere, Frederic, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, Zhukov, Andrei N., Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Biondo, Ruggero, Burtovoi, Aleksandr, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, De Leo, Yara, Giarrusso, Marina, Liberatore, Alessandro, Berghmans, David, Auchere, Frederic, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, and Zhukov, Andrei N.
Abstract: Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks' formation mechanism and sources are still unresolved, although candidate mechanisms include Alfvenic turbulence, shear-driven Kelvin-Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph on board a Solar Orbiter of a single large propagating S-shaped vortex, interpreted as the first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the east and west. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind.
Published: 2022
Full Text: View/download PDF

22. Observation of a Magnetic Switchback in the Solar Corona

Author: Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Biondo, Ruggero, Burtovoi, Aleksandr, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, De Leo, Yara, Giarrusso, Marina, Liberatore, Alessandro, Berghmans, David, Auchere, Frederic, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, Zhukov, Andrei N., Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Biondo, Ruggero, Burtovoi, Aleksandr, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, De Leo, Yara, Giarrusso, Marina, Liberatore, Alessandro, Berghmans, David, Auchere, Frederic, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, and Zhukov, Andrei N.
Abstract: Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks' formation mechanism and sources are still unresolved, although candidate mechanisms include Alfvenic turbulence, shear-driven Kelvin-Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph on board a Solar Orbiter of a single large propagating S-shaped vortex, interpreted as the first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the east and west. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind.
Published: 2022
Full Text: View/download PDF

23. Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar Orbiter Observations

Author: Telloni, Daniele, Zank, Gary P., Sorriso-Valvo, Luca, D'Amicis, Raffaella, Panasenco, Olga, Susino, Roberto, Bruno, Roberto, Perrone, Denise, Adhikari, Laxman, Liang, Haoming, Nakanotani, Masaru, Zhao, Lingling, Hadid, Lina Z., Sanchez-Cano, Beatriz, Verscharen, Daniel, Velli, Marco, Grimani, Catia, Marino, Raffaele, Carbone, Francesco, Mancuso, Salvatore, Biondo, Ruggero, Pagano, Paolo, Reale, Fabio, Bale, Stuart D., Kasper, Justin C., Case, Anthony W., de Wit, Thierry Dudok, Goetz, Keith, Harvey, Peter R., Korreck, Kelly E., Larson, Davin, Livi, Roberto, MacDowall, Robert J., Malaspina, David M., Pulupa, Marc, Stevens, Michael L., Whittlesey, Phyllis, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., De Leo, Yara, Fabi, Michele, Frassati, Federica, Frassetto, Fabio, Giordano, Silvio, Guglielmino, Salvo L., Jerse, Giovanna, Landini, Federico, Liberatore, Alessandro, Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Pancrazzi, Maurizio, Pelizzo, Maria G., Romano, Paolo, Sasso, Clementina, Schuhle, Udo, Slemer, Alessandra, Straus, Thomas, Uslenghi, Michela, Volpicelli, Cosimo A., Zangrilli, Luca, Zuppella, Paola, Abbo, Lucia, Auchere, Frederic, Cuadrado, Regina Aznar, Berlicki, Arkadiusz, Ciaravella, Angela, Lamy, Philippe, Lanzafame, Alessandro, Malvezzi, Marco, Nicolosi, Piergiorgio, Nistico, Giuseppe, Peter, Hardi, Solanki, Sami K., Strachan, Leonard, Tsinganos, Kanaris, Ventura, Rita, Vial, Jean-Claude, Woch, Joachim, Zimbardo, Gaetano, Telloni, Daniele, Zank, Gary P., Sorriso-Valvo, Luca, D'Amicis, Raffaella, Panasenco, Olga, Susino, Roberto, Bruno, Roberto, Perrone, Denise, Adhikari, Laxman, Liang, Haoming, Nakanotani, Masaru, Zhao, Lingling, Hadid, Lina Z., Sanchez-Cano, Beatriz, Verscharen, Daniel, Velli, Marco, Grimani, Catia, Marino, Raffaele, Carbone, Francesco, Mancuso, Salvatore, Biondo, Ruggero, Pagano, Paolo, Reale, Fabio, Bale, Stuart D., Kasper, Justin C., Case, Anthony W., de Wit, Thierry Dudok, Goetz, Keith, Harvey, Peter R., Korreck, Kelly E., Larson, Davin, Livi, Roberto, MacDowall, Robert J., Malaspina, David M., Pulupa, Marc, Stevens, Michael L., Whittlesey, Phyllis, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., De Leo, Yara, Fabi, Michele, Frassati, Federica, Frassetto, Fabio, Giordano, Silvio, Guglielmino, Salvo L., Jerse, Giovanna, Landini, Federico, Liberatore, Alessandro, Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Pancrazzi, Maurizio, Pelizzo, Maria G., Romano, Paolo, Sasso, Clementina, Schuhle, Udo, Slemer, Alessandra, Straus, Thomas, Uslenghi, Michela, Volpicelli, Cosimo A., Zangrilli, Luca, Zuppella, Paola, Abbo, Lucia, Auchere, Frederic, Cuadrado, Regina Aznar, Berlicki, Arkadiusz, Ciaravella, Angela, Lamy, Philippe, Lanzafame, Alessandro, Malvezzi, Marco, Nicolosi, Piergiorgio, Nistico, Giuseppe, Peter, Hardi, Solanki, Sami K., Strachan, Leonard, Tsinganos, Kanaris, Ventura, Rita, Vial, Jean-Claude, Woch, Joachim, and Zimbardo, Gaetano
Abstract: The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R (circle dot) above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local properties of the two streams are different. Specifically, the solar wind emanating from the stronger magnetic field region has a lower bulk flux density, as expected, and is in a state of well-developed Alfvenic turbulence, with low intermittency. This is interpreted in terms of slab turbulence in the context of nearly incompressible magnetohydrodynamics. Conversely, the highly intermittent and poorly developed turbulent behavior of the solar wind from the weaker magnetic field region is presumably due to large magnetic deflections most likely attributed to the presence of switchbacks of interchange reconnection origin.
Published: 2022
Full Text: View/download PDF

24. Closing gaps to our origins. EUVO: the ultraviolet-visible window into the Universe

Author: Gómez de Castro, Ana I., Barstow, Martin A., Baudin, Frederic, Benetti, Stefano, Bouret, Jean Claude, Brosch, Noah, Canet, Ada, de Martino, Domitilla, del Zanna, Giulio, Evans, Chris, France, Kevin, García, Miriam, Gaensicke, Boris, Hillenbrand, Lynne A., Josselin, Eric, Kehrig, Carolina, Lamy, Laurent, Lapington, Jon, Lecavelier des Etangs, Alain, Naletto, Giampiero, Nazé, Yael, Neiner, Coralie, Nichols, Jonathan, Orio, Marina, Pagano, Isabella, Péroux, Céline, Rauw, Gregor, Shore, Steven, Tovmassian, Gagik, ud-Doula, Asif, Gómez de Castro, Ana I., Barstow, Martin A., Baudin, Frederic, Benetti, Stefano, Bouret, Jean Claude, Brosch, Noah, Canet, Ada, de Martino, Domitilla, del Zanna, Giulio, Evans, Chris, France, Kevin, García, Miriam, Gaensicke, Boris, Hillenbrand, Lynne A., Josselin, Eric, Kehrig, Carolina, Lamy, Laurent, Lapington, Jon, Lecavelier des Etangs, Alain, Naletto, Giampiero, Nazé, Yael, Neiner, Coralie, Nichols, Jonathan, Orio, Marina, Pagano, Isabella, Péroux, Céline, Rauw, Gregor, Shore, Steven, Tovmassian, Gagik, and ud-Doula, Asif
Abstract: This article reproduces the contents of the White Paper entitled by the same name submitted to the call issued by the European Space Agency soliciting ideas from the scientific community for the science themes that should be covered during the Voyage 2050 planning cycle. This contribution focus in the investigation of the emergence of life and the role that astronomy has to play in it. Three fundamental areas of activity are identified: [1] measuring the chemical enrichment of the Universe, [2] investigating planet formation and searching for exoplanets with signatures of life and, [3] determining the abundance of amino acids and the chemical routes to amino acid and protein growth in astronomical bodies. This proposal deals with the first two. The building blocks of life in the Universe began as primordial gas processed in stars and mixed at galactic scales. The mechanisms responsible for this development are not well-understood and have changed over the intervening 13 billion years. To follow the evolution of matter over cosmic time, it is necessary to study the strongest (resonance) transitions of the most abundant species in the Universe. Most of them are in the ultraviolet (UV; 950 Å - 3000 Å ) spectral range that is unobservable from the ground; the “missing” metals problem cannot be addressed without this access. Habitable planets grow in protostellar discs under ultraviolet irradiation, a by-product of the accretion process that drives the physical and chemical evolution of discs and young planetary systems. The electronic transitions of the most abundant molecules are pumped by this UV field that is the main oxidizing agent in the disc chemistry and provides unique diagnostics of the planet-forming environment that cannot be accessed from the ground. Knowledge of the variability of the UV radiation field is required for the astrochemical modelling of protoplanetary discs, to understand the formation of planetary atmospheres and the photochemistry of the pre
Published: 2022

25. Observation of a Magnetic Switchback in the Solar Corona

Author: Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Biondo, Ruggero, Burtovoi, Aleksandr, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, De Leo, Yara, Giarrusso, Marina, Liberatore, Alessandro, Berghmans, David, Auchere, Frederic, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, Zhukov, Andrei N., Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Biondo, Ruggero, Burtovoi, Aleksandr, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, De Leo, Yara, Giarrusso, Marina, Liberatore, Alessandro, Berghmans, David, Auchere, Frederic, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, and Zhukov, Andrei N.
Abstract: Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks' formation mechanism and sources are still unresolved, although candidate mechanisms include Alfvenic turbulence, shear-driven Kelvin-Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph on board a Solar Orbiter of a single large propagating S-shaped vortex, interpreted as the first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the east and west. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind.
Published: 2022
Full Text: View/download PDF

26. Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar Orbiter Observations

Author: Telloni, Daniele, Zank, Gary P., Sorriso-Valvo, Luca, D'Amicis, Raffaella, Panasenco, Olga, Susino, Roberto, Bruno, Roberto, Perrone, Denise, Adhikari, Laxman, Liang, Haoming, Nakanotani, Masaru, Zhao, Lingling, Hadid, Lina Z., Sanchez-Cano, Beatriz, Verscharen, Daniel, Velli, Marco, Grimani, Catia, Marino, Raffaele, Carbone, Francesco, Mancuso, Salvatore, Biondo, Ruggero, Pagano, Paolo, Reale, Fabio, Bale, Stuart D., Kasper, Justin C., Case, Anthony W., de Wit, Thierry Dudok, Goetz, Keith, Harvey, Peter R., Korreck, Kelly E., Larson, Davin, Livi, Roberto, MacDowall, Robert J., Malaspina, David M., Pulupa, Marc, Stevens, Michael L., Whittlesey, Phyllis, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., De Leo, Yara, Fabi, Michele, Frassati, Federica, Frassetto, Fabio, Giordano, Silvio, Guglielmino, Salvo L., Jerse, Giovanna, Landini, Federico, Liberatore, Alessandro, Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Pancrazzi, Maurizio, Pelizzo, Maria G., Romano, Paolo, Sasso, Clementina, Schuhle, Udo, Slemer, Alessandra, Straus, Thomas, Uslenghi, Michela, Volpicelli, Cosimo A., Zangrilli, Luca, Zuppella, Paola, Abbo, Lucia, Auchere, Frederic, Cuadrado, Regina Aznar, Berlicki, Arkadiusz, Ciaravella, Angela, Lamy, Philippe, Lanzafame, Alessandro, Malvezzi, Marco, Nicolosi, Piergiorgio, Nistico, Giuseppe, Peter, Hardi, Solanki, Sami K., Strachan, Leonard, Tsinganos, Kanaris, Ventura, Rita, Vial, Jean-Claude, Woch, Joachim, Zimbardo, Gaetano, Telloni, Daniele, Zank, Gary P., Sorriso-Valvo, Luca, D'Amicis, Raffaella, Panasenco, Olga, Susino, Roberto, Bruno, Roberto, Perrone, Denise, Adhikari, Laxman, Liang, Haoming, Nakanotani, Masaru, Zhao, Lingling, Hadid, Lina Z., Sanchez-Cano, Beatriz, Verscharen, Daniel, Velli, Marco, Grimani, Catia, Marino, Raffaele, Carbone, Francesco, Mancuso, Salvatore, Biondo, Ruggero, Pagano, Paolo, Reale, Fabio, Bale, Stuart D., Kasper, Justin C., Case, Anthony W., de Wit, Thierry Dudok, Goetz, Keith, Harvey, Peter R., Korreck, Kelly E., Larson, Davin, Livi, Roberto, MacDowall, Robert J., Malaspina, David M., Pulupa, Marc, Stevens, Michael L., Whittlesey, Phyllis, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., De Leo, Yara, Fabi, Michele, Frassati, Federica, Frassetto, Fabio, Giordano, Silvio, Guglielmino, Salvo L., Jerse, Giovanna, Landini, Federico, Liberatore, Alessandro, Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Pancrazzi, Maurizio, Pelizzo, Maria G., Romano, Paolo, Sasso, Clementina, Schuhle, Udo, Slemer, Alessandra, Straus, Thomas, Uslenghi, Michela, Volpicelli, Cosimo A., Zangrilli, Luca, Zuppella, Paola, Abbo, Lucia, Auchere, Frederic, Cuadrado, Regina Aznar, Berlicki, Arkadiusz, Ciaravella, Angela, Lamy, Philippe, Lanzafame, Alessandro, Malvezzi, Marco, Nicolosi, Piergiorgio, Nistico, Giuseppe, Peter, Hardi, Solanki, Sami K., Strachan, Leonard, Tsinganos, Kanaris, Ventura, Rita, Vial, Jean-Claude, Woch, Joachim, and Zimbardo, Gaetano
Abstract: The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R (circle dot) above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local properties of the two streams are different. Specifically, the solar wind emanating from the stronger magnetic field region has a lower bulk flux density, as expected, and is in a state of well-developed Alfvenic turbulence, with low intermittency. This is interpreted in terms of slab turbulence in the context of nearly incompressible magnetohydrodynamics. Conversely, the highly intermittent and poorly developed turbulent behavior of the solar wind from the weaker magnetic field region is presumably due to large magnetic deflections most likely attributed to the presence of switchbacks of interchange reconnection origin.
Published: 2022
Full Text: View/download PDF

27. Closing gaps to our origins: EUVO: the ultraviolet-visible window into the Universe

Author: Ministerio de Ciencia e Innovación (España), CSIC - Unidad de Recursos de Información Científica para la Investigación (URICI), Gómez de Castro, Ana I., Barstow, Martin A., Baudin, Frederic, Benetti, Stefano, Bouret, Jean Claude, Brosch, Noah, Canet, Ada, de Martino, Domitilla, Zanna, Giulio del, Evans, Chris, France, Kevin, García, Miriam, Gaensicke, Boris, Hillenbrand, Lynne, Josselin, Eric, Kehrig, C., Lamy, Laurent, Lapington, Jon, Etangs, Alain Lecavelier des, Naletto, Giampiero, Nazé, Yael, Neiner, Coralie, Nichols, Jonathan, Orio, Marina, Pagano, Isabella, Peroux, Céline, Rauw, Gregor, Shore, Steven, Tovmassian, Gagik, ud-Doula, Asif, Ministerio de Ciencia e Innovación (España), CSIC - Unidad de Recursos de Información Científica para la Investigación (URICI), Gómez de Castro, Ana I., Barstow, Martin A., Baudin, Frederic, Benetti, Stefano, Bouret, Jean Claude, Brosch, Noah, Canet, Ada, de Martino, Domitilla, Zanna, Giulio del, Evans, Chris, France, Kevin, García, Miriam, Gaensicke, Boris, Hillenbrand, Lynne, Josselin, Eric, Kehrig, C., Lamy, Laurent, Lapington, Jon, Etangs, Alain Lecavelier des, Naletto, Giampiero, Nazé, Yael, Neiner, Coralie, Nichols, Jonathan, Orio, Marina, Pagano, Isabella, Peroux, Céline, Rauw, Gregor, Shore, Steven, Tovmassian, Gagik, and ud-Doula, Asif
Abstract: This article reproduces the contents of the White Paper entitled by the same name submitted to the call issued by the European Space Agency soliciting ideas from the scientific community for the science themes that should be covered during the Voyage 2050 planning cycle. This contribution focus in the investigation of the emergence of life and the role that astronomy has to play in it. Three fundamental areas of activity are identified: [1] measuring the chemical enrichment of the Universe, [2] investigating planet formation and searching for exoplanets with signatures of life and, [3] determining the abundance of amino acids and the chemical routes to amino acid and protein growth in astronomical bodies. This proposal deals with the first two. The building blocks of life in the Universe began as primordial gas processed in stars and mixed at galactic scales. The mechanisms responsible for this development are not well-understood and have changed over the intervening 13 billion years. To follow the evolution of matter over cosmic time, it is necessary to study the strongest (resonance) transitions of the most abundant species in the Universe. Most of them are in the ultraviolet (UV; 950 Å - 3000 Å ) spectral range that is unobservable from the ground; the “missing” metals problem cannot be addressed without this access. Habitable planets grow in protostellar discs under ultraviolet irradiation, a by-product of the accretion process that drives the physical and chemical evolution of discs and young planetary systems. The electronic transitions of the most abundant molecules are pumped by this UV field that is the main oxidizing agent in the disc chemistry and provides unique diagnostics of the planet-forming environment that cannot be accessed from the ground. Knowledge of the variability of the UV radiation field is required for the astrochemical modelling of protoplanetary discs, to understand the formation of planetary atmospheres and the photochemistry of the pre
Published: 2022

28. Observation of a Magnetic Switchback in the Solar Corona

Author: Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Biondo, Ruggero, Burtovoi, Aleksandr, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, De Leo, Yara, Giarrusso, Marina, Liberatore, Alessandro, Berghmans, David, Auchere, Frederic, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, Zhukov, Andrei N., Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Biondo, Ruggero, Burtovoi, Aleksandr, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, De Leo, Yara, Giarrusso, Marina, Liberatore, Alessandro, Berghmans, David, Auchere, Frederic, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, and Zhukov, Andrei N.
Abstract: Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks' formation mechanism and sources are still unresolved, although candidate mechanisms include Alfvenic turbulence, shear-driven Kelvin-Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph on board a Solar Orbiter of a single large propagating S-shaped vortex, interpreted as the first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the east and west. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind.
Published: 2022
Full Text: View/download PDF

29. Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar Orbiter Observations

Author: Telloni, Daniele, Zank, Gary P., Sorriso-Valvo, Luca, D'Amicis, Raffaella, Panasenco, Olga, Susino, Roberto, Bruno, Roberto, Perrone, Denise, Adhikari, Laxman, Liang, Haoming, Nakanotani, Masaru, Zhao, Lingling, Hadid, Lina Z., Sanchez-Cano, Beatriz, Verscharen, Daniel, Velli, Marco, Grimani, Catia, Marino, Raffaele, Carbone, Francesco, Mancuso, Salvatore, Biondo, Ruggero, Pagano, Paolo, Reale, Fabio, Bale, Stuart D., Kasper, Justin C., Case, Anthony W., de Wit, Thierry Dudok, Goetz, Keith, Harvey, Peter R., Korreck, Kelly E., Larson, Davin, Livi, Roberto, MacDowall, Robert J., Malaspina, David M., Pulupa, Marc, Stevens, Michael L., Whittlesey, Phyllis, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., De Leo, Yara, Fabi, Michele, Frassati, Federica, Frassetto, Fabio, Giordano, Silvio, Guglielmino, Salvo L., Jerse, Giovanna, Landini, Federico, Liberatore, Alessandro, Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Pancrazzi, Maurizio, Pelizzo, Maria G., Romano, Paolo, Sasso, Clementina, Schuhle, Udo, Slemer, Alessandra, Straus, Thomas, Uslenghi, Michela, Volpicelli, Cosimo A., Zangrilli, Luca, Zuppella, Paola, Abbo, Lucia, Auchere, Frederic, Cuadrado, Regina Aznar, Berlicki, Arkadiusz, Ciaravella, Angela, Lamy, Philippe, Lanzafame, Alessandro, Malvezzi, Marco, Nicolosi, Piergiorgio, Nistico, Giuseppe, Peter, Hardi, Solanki, Sami K., Strachan, Leonard, Tsinganos, Kanaris, Ventura, Rita, Vial, Jean-Claude, Woch, Joachim, Zimbardo, Gaetano, Telloni, Daniele, Zank, Gary P., Sorriso-Valvo, Luca, D'Amicis, Raffaella, Panasenco, Olga, Susino, Roberto, Bruno, Roberto, Perrone, Denise, Adhikari, Laxman, Liang, Haoming, Nakanotani, Masaru, Zhao, Lingling, Hadid, Lina Z., Sanchez-Cano, Beatriz, Verscharen, Daniel, Velli, Marco, Grimani, Catia, Marino, Raffaele, Carbone, Francesco, Mancuso, Salvatore, Biondo, Ruggero, Pagano, Paolo, Reale, Fabio, Bale, Stuart D., Kasper, Justin C., Case, Anthony W., de Wit, Thierry Dudok, Goetz, Keith, Harvey, Peter R., Korreck, Kelly E., Larson, Davin, Livi, Roberto, MacDowall, Robert J., Malaspina, David M., Pulupa, Marc, Stevens, Michael L., Whittlesey, Phyllis, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., De Leo, Yara, Fabi, Michele, Frassati, Federica, Frassetto, Fabio, Giordano, Silvio, Guglielmino, Salvo L., Jerse, Giovanna, Landini, Federico, Liberatore, Alessandro, Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Pancrazzi, Maurizio, Pelizzo, Maria G., Romano, Paolo, Sasso, Clementina, Schuhle, Udo, Slemer, Alessandra, Straus, Thomas, Uslenghi, Michela, Volpicelli, Cosimo A., Zangrilli, Luca, Zuppella, Paola, Abbo, Lucia, Auchere, Frederic, Cuadrado, Regina Aznar, Berlicki, Arkadiusz, Ciaravella, Angela, Lamy, Philippe, Lanzafame, Alessandro, Malvezzi, Marco, Nicolosi, Piergiorgio, Nistico, Giuseppe, Peter, Hardi, Solanki, Sami K., Strachan, Leonard, Tsinganos, Kanaris, Ventura, Rita, Vial, Jean-Claude, Woch, Joachim, and Zimbardo, Gaetano
Abstract: The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R (circle dot) above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local properties of the two streams are different. Specifically, the solar wind emanating from the stronger magnetic field region has a lower bulk flux density, as expected, and is in a state of well-developed Alfvenic turbulence, with low intermittency. This is interpreted in terms of slab turbulence in the context of nearly incompressible magnetohydrodynamics. Conversely, the highly intermittent and poorly developed turbulent behavior of the solar wind from the weaker magnetic field region is presumably due to large magnetic deflections most likely attributed to the presence of switchbacks of interchange reconnection origin.
Published: 2022
Full Text: View/download PDF

30. Connecting Solar Orbiter remote-sensing observations and Parker Solar Probe in-situ measurements with a numerical MHD reconstruction of the Parker spiral

Author: Biondo, Ruggero, Bemporad, Alessandro, Pagano, Paolo, Telloni, Daniele, Reale, Fabio, Romoli, Marco, Andretta, Vincenzo, Antonucci, Ester, Da Deppo, Vania, De Leo, Yara, Fineschi, Silvano, Heinzel, Petr, Moses, Daniel, Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Landini, Federico, Sasso, Clementina, Susino, Roberto, Jerse, Giovanna, Uslenghi, Michela, Pancrazzi, Maurizio, Biondo, Ruggero, Bemporad, Alessandro, Pagano, Paolo, Telloni, Daniele, Reale, Fabio, Romoli, Marco, Andretta, Vincenzo, Antonucci, Ester, Da Deppo, Vania, De Leo, Yara, Fineschi, Silvano, Heinzel, Petr, Moses, Daniel, Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Landini, Federico, Sasso, Clementina, Susino, Roberto, Jerse, Giovanna, Uslenghi, Michela, and Pancrazzi, Maurizio
Abstract: As a key feature, NASA's Parker Solar Probe (PSP) and ESA-NASA's Solar Orbiter (SO) missions cooperate to trace solar wind and transients from their sources on the Sun to the inner interplanetary space. The goal of this work is to accurately reconstruct the interplanetary Parker spiral and the connection between coronal features observed remotely by the Metis coronagraph on-board SO and those detected in situ by PSP at the time of the first PSP-SO quadrature of January 2021. We use the Reverse In-situ and MHD Approach (RIMAP), a hybrid analytical-numerical method performing data-driven reconstructions of the Parker spiral. RIMAP solves the MHD equations on the equatorial plane with the PLUTO code, using the measurements collected by PSP between 0.1 and 0.2 AU as boundary conditions. Our reconstruction connects density and wind speed measurements provided by Metis (3-6 solar radii) to those acquired by PSP (21.5 solar radii) along a single streamline. The capability of our MHD model to connect the inner corona observed by Metis and the super Alfv\'enic wind measured by PSP, not only confirms the research pathways provided by multi-spacecraft observations, but also the validity and accuracy of RIMAP reconstructions as a possible test bench to verify models of transient phenomena propagating across the heliosphere, such as coronal mass ejections, solar energetic particles and solar wind switchbacks., Comment: Astronomy & Astrophysics, Solar Orbiter First Results (Nominal Mission Phase), (in press) DOI: 10.1051/0004-6361/202244535
Published: 2022
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31. Investigating the origin of optical and X-ray pulsations of the transitional millisecond pulsar PSR J1023+0038

Author: Illiano, G., Papitto, A., Ambrosino, F., Zanon, A. Miraval, Zelati, F. Coti, Stella, L., Zampieri, L., Burtovoi, A., Campana, S., Casella, P., Cecconi, M., de Martino, D., Fiori, M., Ghedina, A., Gonzales, M., Diaz, M. Hernandez, Israel, G. L., Leone, F., Naletto, G., Ventura, H. Perez, Riverol, C., Riverol, L., Torres, D. F., Turchetta, M., Illiano, G., Papitto, A., Ambrosino, F., Zanon, A. Miraval, Zelati, F. Coti, Stella, L., Zampieri, L., Burtovoi, A., Campana, S., Casella, P., Cecconi, M., de Martino, D., Fiori, M., Ghedina, A., Gonzales, M., Diaz, M. Hernandez, Israel, G. L., Leone, F., Naletto, G., Ventura, H. Perez, Riverol, C., Riverol, L., Torres, D. F., and Turchetta, M.
Abstract: PSR J1023+0038 is the first millisecond pulsar that was ever observed as an optical and UV pulsar. So far, it is the only optical transitional millisecond pulsar. The rotation- and accretion-powered emission mechanisms hardly individually explain the observed characteristics of optical pulsations. A synergistic model, combining these standard emission processes, was proposed to explain the origin of the X-ray/UV/optical pulsations. We study the phase lag between the pulses in the optical and X-ray bands to gain insight into the physical mechanisms that cause it. We performed a detailed timing analysis of simultaneous or quasi-simultaneous observations in the X-ray band, acquired with the XMM-Newton and NICER satellites, and in the optical band, with the fast photometers SiFAP2 (mounted at the 3.6 m Telescopio Nazionale Galileo) and Aqueye+ (mounted at the 1.8 m Copernicus Telescope). We estimated the time lag of the optical pulsation with respect to that in the X-rays by modeling the folded pulse profiles with two harmonic components. Optical pulses lag the X-ray pulses by $\sim$ 150 $\mu$s in observations acquired with instruments (NICER and Aqueye+) whose absolute timing uncertainty is much smaller than the measured lag. We also show that the phase lag between optical and X-ray pulsations lies in a limited range of values, $\delta \phi \in$ (0 $-$ 0.15), which is maintained over timescales of about five years. This indicates that both pulsations originate from the same region, and it supports the hypothesis of a common emission mechanism. Our results are interpreted in the shock-driven mini pulsar nebula scenario. This scenario suggests that optical and X-ray pulses are produced by synchrotron emission from the shock that formed within a few light cylinder radii away ($\sim$ 100 km) from the pulsar, where its striped wind encounters the accretion disk inflow., Comment: 13 pages, 6 figures, 5 tables, accepted for publication in A&A
Published: 2022
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32. First measurements and upgrade plans of the MAGIC intensity interferometer

Author: Cortina, Juan, Acciari, V. A., Biland, A., Colombo, E., da Costa, C., Delgado, C., Diaz, C., Fiori, M., Fink, D., Hassan, T., Jimenez-Martinez, I., Lyard, E., Mariotti, M., Martinez, G., Mirzoyan, R., Naletto, G., Polo, M., Produit, N., Rodriguez, J. J., Schweizer, T., Walter, R., Wunderlich, C. W., Zampieri, L., MAGIC, the, collaborations, LST, Cortina, Juan, Acciari, V. A., Biland, A., Colombo, E., da Costa, C., Delgado, C., Diaz, C., Fiori, M., Fink, D., Hassan, T., Jimenez-Martinez, I., Lyard, E., Mariotti, M., Martinez, G., Mirzoyan, R., Naletto, G., Polo, M., Produit, N., Rodriguez, J. J., Schweizer, T., Walter, R., Wunderlich, C. W., Zampieri, L., MAGIC, the, and collaborations, LST
Abstract: The two MAGIC 17-m diameter Imaging Atmospheric Cherenkov Telescopes have been equipped to work also as an intensity interferometer with a deadtime-free, 4-channel, GPU-based, real-time correlator. Operating with baselines between approx. 40 and 90 m the MAGIC interferometer is able to measure stellar diameters of 0.5-1 mas in the 400-440 nm wavelength range with a sensitivity roughly 10 times better than that achieved in the 1970s by the Narrabri Stellar Intensity Interferometer. Besides, active mirror control allows to split the primary mirrors into sub-mirrors. This allows to make simultaneous calibration measurements of the zero-baseline correlation or to simultaneously collect six baselines below 17 m with almost arbitrary orientation, corresponding to angular scales of approx. 1-50 mas. We plan to perform test observations adding the nearby Cherenkov Telescope Array (CTA) LST-1 23 m diameter telescope by next year. All three telescope pairs will be correlated simultaneously. Adding LST-1 is expected to increase the sensitivity by at least 1 mag and significantly improve the u-v plane coverage. If successful, the proposed correlator setup is scalable enough to be implemented to the full CTA arrays., Comment: 15 pages, 9 figures, 1 table, SPIE Astronomical Telescopes + Instrumentation 2022
Published: 2022
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33. Investigating the accuracy achievable in reconstructing the angular sizes of stars through stellar intensity interferometry observations

Author: Fiori, Michele, Naletto, Giampiero, Zampieri, Luca, Martínez, Irene Jiménez, Wunderlich, Carolin, Fiori, Michele, Naletto, Giampiero, Zampieri, Luca, Martínez, Irene Jiménez, and Wunderlich, Carolin
Abstract: Context: In recent years, stellar intensity interferometry has seen renewed interest from the astronomical community because it can be efficiently applied to Cherenkov telescope arrays. Aims: We have investigated the accuracy that can be achieved in reconstructing stellar sizes by fitting the visibility curve measured on the ground. The large number of expected available astronomical targets, the limited number of nights in a year, and the likely presence of multiple baselines will require careful planning of the observational strategy to maximise the scientific output. Methods: We studied the trend of the error on the estimated angular size, considering the uniform disk model, by varying several parameters related to the observations, such as the total number of measurements, the integration time, the signal-to-noise ratio, and different positions along the baseline. Results: We found that measuring the value of the zero-baseline correlation is essential to obtain the best possible results. Systems that can measure this value directly or for which it is known in advance will have better sensitivity. We also found that to minimise the integration time, it is sufficient to obtain a second measurement at a baseline half-way between 0 and that corresponding to the first zero of the visibility function. This function does not have to be measured at multiple positions. Finally, we obtained some analytical expressions that can be used under specific conditions to determine the accuracy that can be achieved in reconstructing the angular size of a star in advance. This is useful to optimise the observation schedule., Comment: Accepted for publication by Astronomy & Astrophysics (A&A)
Published: 2022
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34. The ASTRI Mini-Array of Cherenkov Telescopes at the Observatorio del Teide

Author: S., Scuderi, A., Giuliani, G., Pareschi, G., Tosti, O., Catalano, E., Amato, A., Antonelli L., J., Becerra Gonzáles, G., Bellassai, Bigongiari, C., B., Biondo, M., Böttcher, G., Bonanno, G., Bonnoli, P., Bruno, A., Bulgarelli, R., Canestrari, M., Capalbi, P., Caraveo, M., Cardillo, V., Conforti, G., Contino, M., Corpora, A., Costa, G., Cusumano, A., D'Aí, E., de Gouveia Dal Pino, R., Della Ceca, D., Escribano Rodriguez E. Falceta Gonçalves, C., Fermino, M., Fiori, V., Fioretti, M., Fiorini, S., Gallozzi, C., Gargano, S., Garozzo, S., Germani, A., Ghedina, F., Gianotti, S., Giarrusso, R., Gimenes, V., Giordano, A., Grillo, C., Grivel Gelly, D., Impiombato, F., Incardona, S., Incorvaia, S., Iovenitti, A., La Barbera, N., La Palombara, V., La Parola, A., Lamastra, L., Lessio, G., Leto, F., Lo Gerfo, M., Lodi, S., Lombardi, F., Longo, F., Lucarelli, C., Maccarone M., D., Marano, E., Martinetti, S., Mereghetti, A., Micciché, R., Millul, T., Mineo, D., Mollica, G., Morlino, A., Morselli, G., Naletto, G., Nicotra, A., Pagliaro, N., Parmiggiani, G., Piano, F., Pintore, E., Poretti, B., Olmi, G., Rodeghiero, G., Rodriguez Fernandez, P., Romano, G., Romeo, F., Russo, P., Sangiorgi, G., Saturni F., H., Schwarz J., Sciacca, E., G., Sironi, G., Sottile, A., Stamerra, G., Tagliaferri, V., Testa, G., Umana, M., Uslenghi, S., Vercellone, L., Zampieri, R, Zanmar Sanchez, S., Scuderi, A., Giuliani, G., Pareschi, G., Tosti, O., Catalano, E., Amato, A., Antonelli L., J., Becerra Gonzáles, G., Bellassai, Bigongiari, C., B., Biondo, M., Böttcher, G., Bonanno, G., Bonnoli, P., Bruno, A., Bulgarelli, R., Canestrari, M., Capalbi, P., Caraveo, M., Cardillo, V., Conforti, G., Contino, M., Corpora, A., Costa, G., Cusumano, A., D'Aí, E., de Gouveia Dal Pino, R., Della Ceca, D., Escribano Rodriguez E. Falceta Gonçalves, C., Fermino, M., Fiori, V., Fioretti, M., Fiorini, S., Gallozzi, C., Gargano, S., Garozzo, S., Germani, A., Ghedina, F., Gianotti, S., Giarrusso, R., Gimenes, V., Giordano, A., Grillo, C., Grivel Gelly, D., Impiombato, F., Incardona, S., Incorvaia, S., Iovenitti, A., La Barbera, N., La Palombara, V., La Parola, A., Lamastra, L., Lessio, G., Leto, F., Lo Gerfo, M., Lodi, S., Lombardi, F., Longo, F., Lucarelli, C., Maccarone M., D., Marano, E., Martinetti, S., Mereghetti, A., Micciché, R., Millul, T., Mineo, D., Mollica, G., Morlino, A., Morselli, G., Naletto, G., Nicotra, A., Pagliaro, N., Parmiggiani, G., Piano, F., Pintore, E., Poretti, B., Olmi, G., Rodeghiero, G., Rodriguez Fernandez, P., Romano, G., Romeo, F., Russo, P., Sangiorgi, G., Saturni F., H., Schwarz J., Sciacca, E., G., Sironi, G., Sottile, A., Stamerra, G., Tagliaferri, V., Testa, G., Umana, M., Uslenghi, S., Vercellone, L., Zampieri, and R, Zanmar Sanchez
Abstract: The ASTRI Mini-Array (MA) is an INAF project to build and operate a facility to study astronomical sources emitting at very high-energy in the TeV spectral band. The ASTRI MA consists of a group of nine innovative Imaging Atmospheric Cherenkov telescopes. The telescopes will be installed at the Teide Astronomical Observatory of the Instituto de Astrofisica de Canarias (IAC) in Tenerife (Canary Islands, Spain) on the basis of a host agreement with INAF. Thanks to its expected overall performance, better than those of current Cherenkov telescopes' arrays for energies above \sim 5 TeV and up to 100 TeV and beyond, the ASTRI MA will represent an important instrument to perform deep observations of the Galactic and extra-Galactic sky at these energies., Comment: 19 pages, 22 figures
Published: 2022
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35. ASTRI Mini-Array Core Science at the Observatorio del Teide

Author: Vercellone, S., Bigongiari, C., Burtovoi, A., Cardillo, M., Catalano, O., Franceschini, A., Lombardi, S., Nava, L., Pintore, F., Stamerra, A., Tavecchio, F., Zampieri, L., Batista, R. Alves, Amato, E., Antonelli, L. A., Arcaro, C., Gonzalez, J. Becerra, Bonnoli, G., Bottcher, M., Brunetti, G., Compagnino, A. A., Crestan, S., Ai, A. D, Fiori, M., Galanti, G., Giuliani, A., Pino, E. M. de Gouveia Dal, Green, J. G., Lamastra, A., Landoni, M., Lucarelli, F., Morlino, G., Olmi, B., Peretti, E., Piano, G., Ponti, G., Poretti, E., Romano, P., Saturni, F. G., Scuderi, S., Tutone, A., Umana, G., Acosta-Pulido, J. A., Barai, P., Bonanno, A., Bonanno, G., Bruno, P., Bulgarelli, A., Conforti, V., Costa, A., Cusumano, G., Del Santo, M., del Valle, M. V., Della Ceca, R., Falceta-Goncalves, D. A., Fioretti, V., Germani, S., Garcia-Lopez, R. J., Ghedina, A., Giordano, V., Kreter, M., Incardona, F., Iovenitti, S., La Barbera, A., La Palombara, N., La Parola, V., Leto, G., Longo, F., Lopez-Oramas, A., Maccarone, M. C., Mereghetti, S., Millul, R., Naletto, G., Pagliaro, A., Parmiggiani, N., Righi, C., Rodriguez-Ramirez, J. C., Romeo, G., Sangiorgi, P., de Lima, R. Santos, Tagliaferri, G., Testa, V., Tosti, G., Acosta, M. Vazquez, Zywucka, N., Caraveo, P. A., Pareschi, G., Vercellone, S., Bigongiari, C., Burtovoi, A., Cardillo, M., Catalano, O., Franceschini, A., Lombardi, S., Nava, L., Pintore, F., Stamerra, A., Tavecchio, F., Zampieri, L., Batista, R. Alves, Amato, E., Antonelli, L. A., Arcaro, C., Gonzalez, J. Becerra, Bonnoli, G., Bottcher, M., Brunetti, G., Compagnino, A. A., Crestan, S., Ai, A. D, Fiori, M., Galanti, G., Giuliani, A., Pino, E. M. de Gouveia Dal, Green, J. G., Lamastra, A., Landoni, M., Lucarelli, F., Morlino, G., Olmi, B., Peretti, E., Piano, G., Ponti, G., Poretti, E., Romano, P., Saturni, F. G., Scuderi, S., Tutone, A., Umana, G., Acosta-Pulido, J. A., Barai, P., Bonanno, A., Bonanno, G., Bruno, P., Bulgarelli, A., Conforti, V., Costa, A., Cusumano, G., Del Santo, M., del Valle, M. V., Della Ceca, R., Falceta-Goncalves, D. A., Fioretti, V., Germani, S., Garcia-Lopez, R. J., Ghedina, A., Giordano, V., Kreter, M., Incardona, F., Iovenitti, S., La Barbera, A., La Palombara, N., La Parola, V., Leto, G., Longo, F., Lopez-Oramas, A., Maccarone, M. C., Mereghetti, S., Millul, R., Naletto, G., Pagliaro, A., Parmiggiani, N., Righi, C., Rodriguez-Ramirez, J. C., Romeo, G., Sangiorgi, P., de Lima, R. Santos, Tagliaferri, G., Testa, V., Tosti, G., Acosta, M. Vazquez, Zywucka, N., Caraveo, P. A., and Pareschi, G.
Abstract: The ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) Project led by the Italian National Institute for Astrophysics (INAF) is developing and will deploy at the Observatorio del Teide a mini-array (ASTRI Mini-Array) composed of nine telescopes similar to the small-size dual-mirror Schwarzschild-Couder telescope (ASTRI-Horn) currently operating on the slopes of Mt. Etna in Sicily. The ASTRI Mini-Array will surpass the current Cherenkov telescope array differential sensitivity above a few tera-electronvolt (TeV), extending the energy band well above hundreds of TeV. This will allow us to explore a new window of the electromagnetic spectrum, by convolving the sensitivity performance with excellent angular and energy resolution figures. In this paper we describe the Core Science that we will address during the first four years of operation, providing examples of the breakthrough results that we will obtain when dealing with current open questions, such as the acceleration of cosmic rays, cosmology and fundamental physics and the new window, for the TeV energy band, of the time-domain astrophysics., Comment: Published in Journal of High Energy Astrophysics. 46 Figures, 7 Tables
Published: 2022
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36. Observation of Magnetic Switchback in the Solar Corona

Author: Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Berghmans, David, Auchère, Frédéric, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, Zhukov, Andrei N., Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Berghmans, David, Auchère, Frédéric, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, and Zhukov, Andrei N.
Abstract: Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks' formation mechanism and sources are still unresolved, although candidate mechanisms include Alfv\'enic turbulence, shear-driven Kelvin-Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph onboard Solar Orbiter of a single large propagating S-shaped vortex, interpreted as first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the East and West. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind.
Published: 2022
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37. New technique for determining a pulsar period: Waterfall principal component analysis

Author: Cassanelli, Tomas, Naletto, Giampiero, Codogno, Giacomo, Barbieri, Cesare, Verroi, Enrico, Zampieri, Luca, Cassanelli, Tomas, Naletto, Giampiero, Codogno, Giacomo, Barbieri, Cesare, Verroi, Enrico, and Zampieri, Luca
Abstract: This paper describes a new technique for determining the optimal period of a pulsar and consequently its light curve. The implemented technique makes use of the Principal Component Analysis (PCA) applied to the so-called waterfall diagram, which is a bidimensional representation of the pulsar acquired data. In this context we have developed the python package pywpf to easily retrieve the period with the presented method. We applied this technique to sets of data of the brightest pulsars in visible light that we obtained with the fast photon counter Iqueye. Our results are compared with those obtained by different and more classical analyses (e.g., epoch folding), showing that the periods so determined agree within the errors, and that the errors associated to the waterfall-PCA folding technique are slightly smaller than those obtained by the $\chi^2$ epoch folding technique. We also simulated extremely noisy situations, showing that by means of a new merit function associated to the waterfall-PCA folding it is possible to get more confidence on the determined period with respect to the $\chi^2$ epoch folding technique., Comment: Accepted for publication by Astronomy & Astrophysics (A&A)
Published: 2022
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38. A Coronal Mass Ejection followed by a prominence eruption and a plasma blob as observed by Solar Orbiter

Author: Bemporad, A., Andretta, V., Susino, R., Mancuso, S., Spadaro, D., Mierla, M., Berghmans, D., D'Huys, E., Zhukov, A. N., Talpeanu, D. -C., Colaninno, R., Hess, P., Koza, J., Jejcic, S., Heinzel, P., Antonucci, E., Da Deppo, V., Fineschi, S., Frassati, F., Jerse, G., Landini, F., Naletto, G., Nicolini, G., Pancrazzi, M., Romoli, M., Sasso, C., Slemer, A., Stangalini, M., Teriaca, L., Bemporad, A., Andretta, V., Susino, R., Mancuso, S., Spadaro, D., Mierla, M., Berghmans, D., D'Huys, E., Zhukov, A. N., Talpeanu, D. -C., Colaninno, R., Hess, P., Koza, J., Jejcic, S., Heinzel, P., Antonucci, E., Da Deppo, V., Fineschi, S., Frassati, F., Jerse, G., Landini, F., Naletto, G., Nicolini, G., Pancrazzi, M., Romoli, M., Sasso, C., Slemer, A., Stangalini, M., and Teriaca, L.
Abstract: On February 12, 2021 two subsequent eruptions occurred above the West limb, as seen along the Sun-Earth line. The first event was a typical slow Coronal Mass Ejection (CME), followed $\sim 7$ hours later by a smaller and collimated prominence eruption, originating Southward with respect to the CME, followed by a plasma blob. These events were observed not only by SOHO and STEREO-A missions, but also by the suite of remote sensing instruments on-board Solar Orbiter (SolO). This work shows how data acquired by the Full Sun Imager (FSI), Metis coronagraph, and Heliospheric Imager (SoloHI) from the SolO perspective can be combined to study the eruptions and the different source regions. Moreover, we show how Metis data can be analyzed to provide new information about solar eruptions. Different 3D reconstruction methods were applied to the data acquired by different spacecraft including remote sensing instruments on-board SolO. Images acquired by both Metis channels in the Visible Light (VL) and H I Lyman$-\alpha$ line (UV) were combined to derive physical information on the expanding plasma. The polarization ratio technique was also applied for the first time to the Metis images acquired in the VL channel. The two eruptions were followed in 3D from their source region to their expansion in the intermediate corona. Thanks to the combination of VL and UV Metis data, the formation of a post-CME Current Sheet (CS) was followed for the first time in the intermediate corona. The plasma temperature gradient across a post-CME blob propagating along the CS was also measured for the first time. Application of the polarization ratio technique to Metis data shows that, thanks to the combination of four different polarization measurements, the errors are reduced by $\sim 5-7$\%, thus better constraining the 3D distribution of plasma., Comment: 15 pages, 14 figures, accepted for publication on A&A
Published: 2022
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39. Deep upper limit on the optical emission during a hard X-ray burst from the magnetar SGR J1935+2154

Author: Zampieri, Luca, Mereghetti, Sandro, Turolla, Roberto, Naletto, Giampiero, Ochner, Paolo, Burtovoi, Aleksandr, Fiori, Michele, Guidorzi, Cristiano, Nicastro, Luciano, Palazzi, Eliana, Pilia, Maura, Possenti, Andrea, Zampieri, Luca, Mereghetti, Sandro, Turolla, Roberto, Naletto, Giampiero, Ochner, Paolo, Burtovoi, Aleksandr, Fiori, Michele, Guidorzi, Cristiano, Nicastro, Luciano, Palazzi, Eliana, Pilia, Maura, and Possenti, Andrea
Abstract: In September 2021 the magnetar SGR J1935+2154 entered a stage of burst/flaring activity in the hard X-ray band. On September 10, 2021 we observed SGR J1935+2154 with the fiber-fed fast optical photon counter IFI+Iqueye, mounted at the 1.22 m Galileo telescope in Asiago. During one of the IFI+Iqueye observing windows a hard X-ray burst was detected with the Fermi Gamma-ray Burst Monitor. We performed a search for any significant increase in the count rate on the 1-s, 10-ms and 1-ms binned IFI+Iqueye light curves around the time of the Fermi burst. No significant peak was detected with a significance above 3$\sigma$ in an interval of $\pm$90 s around the burst. Correcting for interstellar extinction ($A_V \simeq 5.8$ mag), the IFI+Iqueye upper limits to any possible optical burst from SGR J1935+2154 are $V=10.1$ mag, $V=7.2$ mag and $V=5.8$ mag for the 1-s, 10-ms and 1-ms binned light curves, respectively. The corresponding extinction corrected upper limits to the fluence (specific fluence) are $3.1 \times 10^{-10}$ erg cm$^{-2}$ (0.35 Jy s), $4.2 \times 10^{-11}$ erg cm$^{-2}$ (4.8 Jy $\cdot$ 10 ms), and $1.6 \times 10^{-11}$ erg cm$^{-2}$ (17.9 Jy ms), orders of magnitude deeper than any previous simultaneous optical limit on a magnetar burst. The IFI+Iqueye measurement can also place a more stringent constraint to the spectral index of the optical to hard X-ray fluence of SGR J1935+2154, implying a spectrum steeper than $\nu^{0.64}$. Fast optical timing observations of bursts associated with radio emission have then the potential to yield a detection., Comment: 8 pages, 4 figures, accepted for publication in The Astrophysical Journal Letters
Published: 2022
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40. Measuring the F-corona intensity through time correlation of total and polarized visible light images

Author: Burtovoi, A., Naletto, G., Dolei, S., Spadaro, D., Romoli, M., Landini, F., De Leo, Y., Burtovoi, A., Naletto, G., Dolei, S., Spadaro, D., Romoli, M., Landini, F., and De Leo, Y.
Abstract: We present a new correlation method for deriving the F-corona intensity distribution, which is based on the analysis of the evolution of the total and polarized visible light (VL) images. We studied the one-month variation profiles of the total and polarized brightness acquired with Large Angle Spectrometric COronagraph (LASCO-C2) and found that in some regions they are highly correlated. Assuming that the F-corona does not vary significantly on a timescale of one month, we estimated its intensity in the high-correlation regions and reconstructed the corresponding intensity maps both during the solar-minimum and solar-maximum periods. Systematic uncertainties were estimated by performing dedicated simulations. We compared the resulting F-corona images with those determined using the inversion technique and found that the correlation method provides a smoother intensity distribution. We also obtained that the F-corona images calculated for consecutive months show no significant variation. Finally, we note that this method can be applied to the future high-cadence VL observations carried out with the Metis/Solar Orbiter coronagraph., Comment: 16 pages, 21 figures
Published: 2021
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41. Exploring the Solar Wind from its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter - Parker Solar Probe Quadrature

Author: Telloni, Daniele, Andretta, Vincenzo, Antonucci, Ester, Bemporad, Alessandro, Capuano, Giuseppe E., Fineschi, Silvano, Giordano, Silvio, Habbal, Shadia, Perrone, Denise, Pinto, Rui F., Sorriso-Valvo, Luca, Spadaro, Daniele, Susino, Roberto, Woodham, Lloyd D., Zank, Gary P., Romoli, Marco, Bale, Stuart D., Kasper, Justin C., Auchère, Frédéric, Bruno, Roberto, Capobianco, Gerardo, Case, Anthony W., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., Da Deppo, Vania, De Leo, Yara, de Wit, Thierry Dudok, Frassati, Federica, Frassetto, Fabio, Goetz, Keith, Guglielmino, Salvo L., Harvey, Peter R., Heinzel, Petr, Jerse, Giovanna, Korreck, Kelly E., Landini, Federico, Larson, Davin, Liberatore, Alessandro, Livi, Roberto, MacDowall, Robert J., Magli, Enrico, Malaspina, David M., Massone, Giuseppe, Messerotti, Mauro, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Nisticò, Giuseppe, Panasenco, Olga, Pancrazzi, Maurizio, Pelizzo, Maria G., Pulupa, Marc, Reale, Fabio, Romano, Paolo, Sasso, Clementina, Schühle, Udo, Stangalini, Marco, Stevens, Michael L., Strachan, Leonard, Straus, Thomas, Teriaca, Luca, Uslenghi, Michela, Velli, Marco, Verscharen, Daniel, Volpicelli, Cosimo A., Whittlesey, Phyllis, Zangrilli, Luca, Zimbardo, Gaetano, Zuppella, Paola, Telloni, Daniele, Andretta, Vincenzo, Antonucci, Ester, Bemporad, Alessandro, Capuano, Giuseppe E., Fineschi, Silvano, Giordano, Silvio, Habbal, Shadia, Perrone, Denise, Pinto, Rui F., Sorriso-Valvo, Luca, Spadaro, Daniele, Susino, Roberto, Woodham, Lloyd D., Zank, Gary P., Romoli, Marco, Bale, Stuart D., Kasper, Justin C., Auchère, Frédéric, Bruno, Roberto, Capobianco, Gerardo, Case, Anthony W., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., Da Deppo, Vania, De Leo, Yara, de Wit, Thierry Dudok, Frassati, Federica, Frassetto, Fabio, Goetz, Keith, Guglielmino, Salvo L., Harvey, Peter R., Heinzel, Petr, Jerse, Giovanna, Korreck, Kelly E., Landini, Federico, Larson, Davin, Liberatore, Alessandro, Livi, Roberto, MacDowall, Robert J., Magli, Enrico, Malaspina, David M., Massone, Giuseppe, Messerotti, Mauro, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Nisticò, Giuseppe, Panasenco, Olga, Pancrazzi, Maurizio, Pelizzo, Maria G., Pulupa, Marc, Reale, Fabio, Romano, Paolo, Sasso, Clementina, Schühle, Udo, Stangalini, Marco, Stevens, Michael L., Strachan, Leonard, Straus, Thomas, Teriaca, Luca, Uslenghi, Michela, Velli, Marco, Verscharen, Daniel, Volpicelli, Cosimo A., Whittlesey, Phyllis, Zangrilli, Luca, Zimbardo, Gaetano, and Zuppella, Paola
Abstract: This Letter addresses the first Solar Orbiter (SO) -- Parker Solar Probe (PSP) quadrature, occurring on January 18, 2021, to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO can be tracked to PSP, orbiting at 0.1 au, thus allowing the local properties of the solar wind to be linked to the coronal source region from where it originated. Thanks to the close approach of PSP to the Sun and the simultaneous Metis observation of the solar corona, the flow-aligned magnetic field and the bulk kinetic energy flux density can be empirically inferred along the coronal current sheet with an unprecedented accuracy, allowing in particular estimation of the Alfv\'en radius at 8.7 solar radii during the time of this event. This is thus the very first study of the same solar wind plasma as it expands from the sub-Alfv\'enic solar corona to just above the Alfv\'en surface., Comment: 10 pages, 4 figures
Published: 2021
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42. Stellar intensity interferometry of Vega in photon counting mode

Author: Zampieri, Luca, Naletto, Giampiero, Burtovoi, Aleksandr, Fiori, Michele, Barbieri, Cesare, Zampieri, Luca, Naletto, Giampiero, Burtovoi, Aleksandr, Fiori, Michele, and Barbieri, Cesare
Abstract: Stellar Intensity Interferometry is a technique based on the measurement of the second order spatial correlation of the light emitted from a star. The physical information provided by these measurements is the angular size and structure of the emitting source. A worldwide effort is presently under way to implement stellar intensity interferometry on telescopes separated by long baselines and on future arrays of Cherenkov telescopes. We describe an experiment of this type, realized at the Asiago Observatory (Italy), in which we performed for the first time measurements of the correlation counting photon coincidences in post-processing by means of a single photon software correlator and exploiting entirely the quantum properties of the light emitted from a star. We successfully detected the temporal correlation of Vega at zero baseline and performed a measurement of the correlation on a projected baseline of $\sim$2 km. The average discrete degree of coherence at zero baseline for Vega is $< g^{(2)} > \, = 1.0034 \pm 0.0008$, providing a detection with a signal-to-noise ratio $S/N \gtrsim 4$. No correlation is detected over the km baseline. The measurements are consistent with the expected degree of spatial coherence for a source with the 3.3 mas angular diameter of Vega. The experience gained with the Asiago experiment will serve for future implementations of stellar intensity interferometry on long-baseline arrays of Cherenkov telescopes., Comment: 10 pages, 6 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society
Published: 2021
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43. First light observations of the solar wind in the outer corona with the Metis coronagraph

Author: Romoli, M., Antonucci, E., Andretta, V., Capuano, G. E., Da Deppo, V., De Leo, Y., Downs, C., Fineschi, S., Heinzel, P., Landini, F., Liberatore, A., Naletto, G., Nicolini, G., Pancrazzi, M., Sasso, C., Spadaro, D., Susino, R., Telloni, D., Teriaca, L., Uslenghi, M., Wang, Y. M., Bemporad, A., Capobianco, G., Casti, M., Fabi, M., Frassati, F., Frassetto, F., Giordano, S., Grimani, C., Jerse, G., Magli, E., Massone, G., Messerotti, M., Moses, D., Pelizzo, M. G., Romano, P., Schühle, U., Slemer, A., Stangalini, M., Straus, T., Volpicelli, C. A., Zangrilli, L., Zuppella, P., Abbo, L., Auchére, F., Cuadrado, R. Aznar, Berlicki, A., Bruno, R., Ciaravella, A., D'Amicis, R., Lamy, P., Lanzafame, A., Malvezzi, A. M., Nicolosi, P., Nisticò, G., Peter, H., Plainaki, C., Poletto, L., Reale, F., Solanki, S. K., Strachan, L., Tondello, G., Tsinganos, K., Velli, M., Ventura, R., Vial, J. C., Woch, J., Zimbardo, G., Romoli, M., Antonucci, E., Andretta, V., Capuano, G. E., Da Deppo, V., De Leo, Y., Downs, C., Fineschi, S., Heinzel, P., Landini, F., Liberatore, A., Naletto, G., Nicolini, G., Pancrazzi, M., Sasso, C., Spadaro, D., Susino, R., Telloni, D., Teriaca, L., Uslenghi, M., Wang, Y. M., Bemporad, A., Capobianco, G., Casti, M., Fabi, M., Frassati, F., Frassetto, F., Giordano, S., Grimani, C., Jerse, G., Magli, E., Massone, G., Messerotti, M., Moses, D., Pelizzo, M. G., Romano, P., Schühle, U., Slemer, A., Stangalini, M., Straus, T., Volpicelli, C. A., Zangrilli, L., Zuppella, P., Abbo, L., Auchére, F., Cuadrado, R. Aznar, Berlicki, A., Bruno, R., Ciaravella, A., D'Amicis, R., Lamy, P., Lanzafame, A., Malvezzi, A. M., Nicolosi, P., Nisticò, G., Peter, H., Plainaki, C., Poletto, L., Reale, F., Solanki, S. K., Strachan, L., Tondello, G., Tsinganos, K., Velli, M., Ventura, R., Vial, J. C., Woch, J., and Zimbardo, G.
Abstract: The investigation of the wind in the solar corona initiated with the observations of the resonantly scattered UV emission of the coronal plasma obtained with UVCS-SOHO, designed to measure the wind outflow speed by applying the Doppler dimming diagnostics. Metis on Solar Orbiter complements the UVCS spectroscopic observations, performed during solar activity cycle 23, by simultaneously imaging the polarized visible light and the HI Ly-alpha corona in order to obtain high-spatial and temporal resolution maps of the outward velocity of the continuously expanding solar atmosphere. The Metis observations, on May 15, 2020, provide the first HI Ly-alpha images of the extended corona and the first instantaneous map of the speed of the coronal plasma outflows during the minimum of solar activity and allow us to identify the layer where the slow wind flow is observed. The polarized visible light (580-640 nm), and the UV HI Ly-alpha (121.6 nm) coronal emissions, obtained with the two Metis channels, are combined in order to measure the dimming of the UV emission relative to a static corona. This effect is caused by the outward motion of the coronal plasma along the direction of incidence of the chromospheric photons on the coronal neutral hydrogen. The plasma outflow velocity is then derived as a function of the measured Doppler dimming. The static corona UV emission is simulated on the basis of the plasma electron density inferred from the polarized visible light. This study leads to the identification, in the velocity maps of the solar corona, of the high-density layer about +/-10 deg wide, centered on the extension of a quiet equatorial streamer present at the East limb where the slowest wind flows at about (160 +/- 18) km/s from 4 Rs to 6 Rs. Beyond the boundaries of the high-density layer, the wind velocity rapidly increases, marking the transition between slow and fast wind in the corona.
Published: 2021
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44. Cosmic-ray flux predictions and observations for and with Metis on board Solar Orbiter

Author: Grimani, C., Andretta, V., Chioetto, P., Da Deppo, V., Fabi, M., Gissot, S., Naletto, G., Persici, A., Plainaki, C., Romoli, M., Sabbatini, F., Spadaro, D., Stangalini, M., Telloni, D., Uslenghi, M., Antonucci, E., Bemporad, A., Capobianco, G., Capuano, G., Casti, M., De Leo, Y., Fineschi, S., Frassati, F., Frassetto, F., Heinzel, P., Jerse, G., Landini, F., Liberatore, A., Magli, E., Messerotti, M., Moses, D., Nicolini, G., Pancrazzi, M., Pelizzo, M. G., Romano, P., Sasso, C., Schühle, U., Slemer, A., Straus, T., Susino, R., Teriaca, L., Volpicelli, C. A., von Forstner, J. L. Freiherr, Zuppella, P., Grimani, C., Andretta, V., Chioetto, P., Da Deppo, V., Fabi, M., Gissot, S., Naletto, G., Persici, A., Plainaki, C., Romoli, M., Sabbatini, F., Spadaro, D., Stangalini, M., Telloni, D., Uslenghi, M., Antonucci, E., Bemporad, A., Capobianco, G., Capuano, G., Casti, M., De Leo, Y., Fineschi, S., Frassati, F., Frassetto, F., Heinzel, P., Jerse, G., Landini, F., Liberatore, A., Magli, E., Messerotti, M., Moses, D., Nicolini, G., Pancrazzi, M., Pelizzo, M. G., Romano, P., Sasso, C., Schühle, U., Slemer, A., Straus, T., Susino, R., Teriaca, L., Volpicelli, C. A., von Forstner, J. L. Freiherr, and Zuppella, P.
Abstract: The Metis coronagraph is one of the remote sensing instruments hosted on board the ESA/NASA Solar Orbiter mission. Metis is devoted to carry out the first simultaneous imaging of the solar corona in both visible light (VL) and ultraviolet (UV). High-energy particles penetrate spacecraft materials and may limit the performance of on-board instruments. A study of galactic cosmic-ray (GCR) tracks observed in the first VL images gathered by Metis during the commissioning phase for a total of 60 seconds of exposure time is presented here. A similar analysis is planned for the UV channel. A prediction of the GCR flux up to hundreds of GeV is made here for the first part of the Solar Orbiter mission to study the Metis coronagraph performance. GCR model predictions are compared to observations gathered on board Solar Orbiter by the EPD/HET experiment in the range 10 MeV-100 MeV in the summer 2020 and with previous measurements. Estimated cosmic-ray fluxes above 70 MeV n$^{-1}$ have been also parameterized and used for Monte Carlo simulations aiming at reproducing the cosmic-ray track observations in the Metis coronagraph VL images. The same parameterizations can also be used to study the performance of other detectors. By comparing observations of cosmic-ray tracks in the Metis VL images with FLUKA Monte Carlo simulations of cosmic-ray interactions in the VL detector, it is found that cosmic rays fire a fraction of the order of 10$^{-4}$ of the whole image pixel sample. Therefore, cosmic rays do not affect sensibly the quality of Metis VL images. It is also found that the overall efficiency for cosmic-ray identification in the Metis VL images is approximately equal to the contribution of Z$>$2 particles. As a result, the Metis coronagraph may play the role of a proton monitor for long-term GCR variations during the overall mission duration., Comment: 11 pages, 7 figures, accepted for publication on Astronomy & Astrophysics
Published: 2021
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45. Observational constraints to the dynamics of dust particles in the coma of comet 67P/Churyumov-Gerasimenko

Author: Frattin, Elisa, Bertini, I., Ivanovski, S. L., Marzari, F., Fulle, M., Zakharov, V. V., Moreno, F., Naletto, G., Lazzarin, M., Cambianica, P., Cremonese, G., Ferrari, S., Ferri, F., Guettler, C., La Forgia, F., Lucchetti, A., Pajola, M., Penasa, L., Rotundi, A., Sierks, H., Tubiana, C., Frattin, Elisa, Bertini, I., Ivanovski, S. L., Marzari, F., Fulle, M., Zakharov, V. V., Moreno, F., Naletto, G., Lazzarin, M., Cambianica, P., Cremonese, G., Ferrari, S., Ferri, F., Guettler, C., La Forgia, F., Lucchetti, A., Pajola, M., Penasa, L., Rotundi, A., Sierks, H., and Tubiana, C.
Abstract: In this work we aim to characterise the dust motion in the inner coma of comet 67P/Churyumov- Gerasimenko to provide constraints for theoretical 3D coma models. The OSIRIS camera onboard the Rosetta mission was able for the first time to acquire images of single dust particles from inside the cometary coma, very close to the nucleus. We analyse a large number of particles, performing a significant statistic of their behaviour during the post perihelion period, when the spacecraft covered distances from the nucleus ranging between 80 and 400 km. We describe the particle trajectories, investigating their orientation and finding highly radial motion with respect to the nucleus. Then, from the particle brightness profiles, we derive a particle rotational frequency of v < 3.6 Hz, revealing that they are slow rotators and do not undergo fragmentation. We use scattering models to compare the observed spectral radiance of the particles with the simulated ones in order to estimate their size, finding values that range from millimetres up to centimetres. The statistics performed in this paper provide useful parameters to constrain the cometary coma dynamical models.
Published: 2021
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46. A journey of exploration to the polar regions of a star: probing the solar poles and the heliosphere from high helio-latitude

Author: Harra, Louise, Andretta, Vincenzo, Appourchaux, Thierry, Baudin, Frédéric, Bellot-Rubio, Luis, Birch, Aaron C., Boumier, Patrick, Cameron, Robert H., Carlsson, Matts, Corbard, Thierry, Davies, Jackie, Fazakerley, Andrew, Fineschi, Silvano, Finsterle, Wolfgang, Gizon, Laurent, Harrison, Richard, Hassler, Donald M., Leibacher, John, Liewer, Paulett, MacDonald, Malcolm, Maksimovic, Milan, Murphy, Neil, Naletto, Giampiero, Nigro, Giuseppina, Owen, Christopher, Martínez-Pillet, Valentín, Rochus, Pierre, Romoli, Marco, Sekii, Takashi, Spadaro, Daniele, Veronig, Astrid, Schmutz, Werner, Harra, Louise, Andretta, Vincenzo, Appourchaux, Thierry, Baudin, Frédéric, Bellot-Rubio, Luis, Birch, Aaron C., Boumier, Patrick, Cameron, Robert H., Carlsson, Matts, Corbard, Thierry, Davies, Jackie, Fazakerley, Andrew, Fineschi, Silvano, Finsterle, Wolfgang, Gizon, Laurent, Harrison, Richard, Hassler, Donald M., Leibacher, John, Liewer, Paulett, MacDonald, Malcolm, Maksimovic, Milan, Murphy, Neil, Naletto, Giampiero, Nigro, Giuseppina, Owen, Christopher, Martínez-Pillet, Valentín, Rochus, Pierre, Romoli, Marco, Sekii, Takashi, Spadaro, Daniele, Veronig, Astrid, and Schmutz, Werner
Abstract: A mission to view the solar poles from high helio-latitudes (above 60$^\circ$) will build on the experience of Solar Orbiter as well as a long heritage of successful solar missions and instrumentation (e.g. SOHO \cite{SOHO}, STEREO \cite{stereo}, Hinode \cite{Hinode}, SDO \cite{SDO}), but will focus for the first time on the solar poles, enabling scientific investigations that cannot be done by any other mission. One of the major mysteries of the Sun is the solar cycle. The activity cycle of the Sun drives the structure and behaviour of the heliosphere and is, of course, the driver of space weather. In addition, solar activity and variability provides fluctuating input into the Earth climate models, and these same physical processes are applicable to stellar systems hosting exoplanets. One of the main obstructions to understanding the solar cycle, and hence all solar activity, is our current lack of understanding of the polar regions. In this White Paper, submitted to the European Space Agency in response to the Voyage 2050 call, we describe a mission concept that aims to address this fundamental issue. In parallel, we recognise that viewing the Sun from above the polar regions enables further scientific advantages, beyond those related to the solar cycle, such as unique and powerful studies of coronal mass ejection processes, from a global perspective, and studies of coronal structure and activity in polar regions. Not only will these provide important scientific advances for fundamental stellar physics research, they will feed into our understanding of impacts on the Earth and other planets' space environment., Comment: 29 pages, 9 figures, White paper for ESA Voyage 2050
Published: 2021
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47. Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter-Parker Solar Probe Quadrature

Author: Telloni, Daniele, Andretta, Vincenzo, Antonucci, Ester, Bemporad, Alessandro, Capuano, Giuseppe E., Fineschi, Silvano, Giordano, Silvio, Habbal, Shadia, Perrone, Denise, Pinto, Rui F., Sorriso-Valvo, Luca, Spadaro, Daniele, Susino, Roberto, Woodham, Lloyd D., Zank, Gary P., Romoli, Marco, Bale, Stuart D., Kasper, Justin C., Auchere, Frederic, Bruno, Roberto, Capobianco, Gerardo, Case, Anthony W., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., Da Deppo, Vania, De Leo, Yara, de Wit, Thierry Dudok, Frassati, Federica, Frassetto, Fabio, Goetz, Keith, Guglielmino, Salvo L., Harvey, Peter R., Heinzel, Petr, Jerse, Giovanna, Korreck, Kelly E., Landini, Federico, Larson, Davin, Liberatore, Alessandro, Livi, Roberto, MacDowall, Robert J., Magli, Enrico, Malaspina, David M., Massone, Giuseppe, Messerotti, Mauro, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Nistico, Giuseppe, Panasenco, Olga, Pancrazzi, Maurizio, Pelizzo, Maria G., Pulupa, Marc, Reale, Fabio, Romano, Paolo, Sasso, Clementina, Schuehle, Udo, Stangalini, Marco, Stevens, Michael L., Strachan, Leonard, Straus, Thomas, Teriaca, Luca, Uslenghi, Michela, Velli, Marco, Verscharen, Daniel, Volpicelli, Cosimo A., Whittlesey, Phyllis, Zangrilli, Luca, Zimbardo, Gaetano, Zuppella, Paola, Telloni, Daniele, Andretta, Vincenzo, Antonucci, Ester, Bemporad, Alessandro, Capuano, Giuseppe E., Fineschi, Silvano, Giordano, Silvio, Habbal, Shadia, Perrone, Denise, Pinto, Rui F., Sorriso-Valvo, Luca, Spadaro, Daniele, Susino, Roberto, Woodham, Lloyd D., Zank, Gary P., Romoli, Marco, Bale, Stuart D., Kasper, Justin C., Auchere, Frederic, Bruno, Roberto, Capobianco, Gerardo, Case, Anthony W., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., Da Deppo, Vania, De Leo, Yara, de Wit, Thierry Dudok, Frassati, Federica, Frassetto, Fabio, Goetz, Keith, Guglielmino, Salvo L., Harvey, Peter R., Heinzel, Petr, Jerse, Giovanna, Korreck, Kelly E., Landini, Federico, Larson, Davin, Liberatore, Alessandro, Livi, Roberto, MacDowall, Robert J., Magli, Enrico, Malaspina, David M., Massone, Giuseppe, Messerotti, Mauro, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Nistico, Giuseppe, Panasenco, Olga, Pancrazzi, Maurizio, Pelizzo, Maria G., Pulupa, Marc, Reale, Fabio, Romano, Paolo, Sasso, Clementina, Schuehle, Udo, Stangalini, Marco, Stevens, Michael L., Strachan, Leonard, Straus, Thomas, Teriaca, Luca, Uslenghi, Michela, Velli, Marco, Verscharen, Daniel, Volpicelli, Cosimo A., Whittlesey, Phyllis, Zangrilli, Luca, Zimbardo, Gaetano, and Zuppella, Paola
Abstract: This Letter addresses the first Solar Orbiter (SO)-Parker Solar Probe (PSP) quadrature, occurring on 2021 January 18 to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in the corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO can be tracked to PSP, orbiting at 0.1 au, thus allowing the local properties of the solar wind to be linked to the coronal source region from where it originated. Thanks to the close approach of PSP to the Sun and the simultaneous Metis observation of the solar corona, the flow-aligned magnetic field and the bulk kinetic energy flux density can be empirically inferred along the coronal current sheet with an unprecedented accuracy, allowing in particular estimation of the Alfven radius at 8.7 solar radii during the time of this event. This is thus the very first study of the same solar wind plasma as it expands from the sub-Alfvenic solar corona to just above the Alfven surface.
Published: 2021
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48. Measuring the F-corona intensity through time correlation of total and polarized visible light images

Author: Burtovoi, A., Naletto, G., Dolei, S., Spadaro, D., Romoli, M., Landini, F., De Leo, Y., Burtovoi, A., Naletto, G., Dolei, S., Spadaro, D., Romoli, M., Landini, F., and De Leo, Y.
Abstract: We present a new correlation method for deriving the F-corona intensity distribution, which is based on the analysis of the evolution of the total and polarized visible light (VL) images. We studied the one-month variation profiles of the total and polarized brightness acquired with Large Angle Spectrometric COronagraph (LASCO-C2) and found that in some regions they are highly correlated. Assuming that the F-corona does not vary significantly on a timescale of one month, we estimated its intensity in the high-correlation regions and reconstructed the corresponding intensity maps both during the solar-minimum and solar-maximum periods. Systematic uncertainties were estimated by performing dedicated simulations. We compared the resulting F-corona images with those determined using the inversion technique and found that the correlation method provides a smoother intensity distribution. We also obtained that the F-corona images calculated for consecutive months show no significant variation. Finally, we note that this method can be applied to the future high-cadence VL observations carried out with the Metis/Solar Orbiter coronagraph., Comment: 16 pages, 21 figures
Published: 2021
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49. Exploring the Solar Wind from its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter - Parker Solar Probe Quadrature

Author: Telloni, Daniele, Andretta, Vincenzo, Antonucci, Ester, Bemporad, Alessandro, Capuano, Giuseppe E., Fineschi, Silvano, Giordano, Silvio, Habbal, Shadia, Perrone, Denise, Pinto, Rui F., Sorriso-Valvo, Luca, Spadaro, Daniele, Susino, Roberto, Woodham, Lloyd D., Zank, Gary P., Romoli, Marco, Bale, Stuart D., Kasper, Justin C., Auchère, Frédéric, Bruno, Roberto, Capobianco, Gerardo, Case, Anthony W., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., Da Deppo, Vania, De Leo, Yara, de Wit, Thierry Dudok, Frassati, Federica, Frassetto, Fabio, Goetz, Keith, Guglielmino, Salvo L., Harvey, Peter R., Heinzel, Petr, Jerse, Giovanna, Korreck, Kelly E., Landini, Federico, Larson, Davin, Liberatore, Alessandro, Livi, Roberto, MacDowall, Robert J., Magli, Enrico, Malaspina, David M., Massone, Giuseppe, Messerotti, Mauro, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Nisticò, Giuseppe, Panasenco, Olga, Pancrazzi, Maurizio, Pelizzo, Maria G., Pulupa, Marc, Reale, Fabio, Romano, Paolo, Sasso, Clementina, Schühle, Udo, Stangalini, Marco, Stevens, Michael L., Strachan, Leonard, Straus, Thomas, Teriaca, Luca, Uslenghi, Michela, Velli, Marco, Verscharen, Daniel, Volpicelli, Cosimo A., Whittlesey, Phyllis, Zangrilli, Luca, Zimbardo, Gaetano, Zuppella, Paola, Telloni, Daniele, Andretta, Vincenzo, Antonucci, Ester, Bemporad, Alessandro, Capuano, Giuseppe E., Fineschi, Silvano, Giordano, Silvio, Habbal, Shadia, Perrone, Denise, Pinto, Rui F., Sorriso-Valvo, Luca, Spadaro, Daniele, Susino, Roberto, Woodham, Lloyd D., Zank, Gary P., Romoli, Marco, Bale, Stuart D., Kasper, Justin C., Auchère, Frédéric, Bruno, Roberto, Capobianco, Gerardo, Case, Anthony W., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., Da Deppo, Vania, De Leo, Yara, de Wit, Thierry Dudok, Frassati, Federica, Frassetto, Fabio, Goetz, Keith, Guglielmino, Salvo L., Harvey, Peter R., Heinzel, Petr, Jerse, Giovanna, Korreck, Kelly E., Landini, Federico, Larson, Davin, Liberatore, Alessandro, Livi, Roberto, MacDowall, Robert J., Magli, Enrico, Malaspina, David M., Massone, Giuseppe, Messerotti, Mauro, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Nisticò, Giuseppe, Panasenco, Olga, Pancrazzi, Maurizio, Pelizzo, Maria G., Pulupa, Marc, Reale, Fabio, Romano, Paolo, Sasso, Clementina, Schühle, Udo, Stangalini, Marco, Stevens, Michael L., Strachan, Leonard, Straus, Thomas, Teriaca, Luca, Uslenghi, Michela, Velli, Marco, Verscharen, Daniel, Volpicelli, Cosimo A., Whittlesey, Phyllis, Zangrilli, Luca, Zimbardo, Gaetano, and Zuppella, Paola
Abstract: This Letter addresses the first Solar Orbiter (SO) -- Parker Solar Probe (PSP) quadrature, occurring on January 18, 2021, to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO can be tracked to PSP, orbiting at 0.1 au, thus allowing the local properties of the solar wind to be linked to the coronal source region from where it originated. Thanks to the close approach of PSP to the Sun and the simultaneous Metis observation of the solar corona, the flow-aligned magnetic field and the bulk kinetic energy flux density can be empirically inferred along the coronal current sheet with an unprecedented accuracy, allowing in particular estimation of the Alfv\'en radius at 8.7 solar radii during the time of this event. This is thus the very first study of the same solar wind plasma as it expands from the sub-Alfv\'enic solar corona to just above the Alfv\'en surface., Comment: 10 pages, 4 figures
Published: 2021
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50. Stellar intensity interferometry of Vega in photon counting mode

Author: Zampieri, Luca, Naletto, Giampiero, Burtovoi, Aleksandr, Fiori, Michele, Barbieri, Cesare, Zampieri, Luca, Naletto, Giampiero, Burtovoi, Aleksandr, Fiori, Michele, and Barbieri, Cesare
Abstract: Stellar Intensity Interferometry is a technique based on the measurement of the second order spatial correlation of the light emitted from a star. The physical information provided by these measurements is the angular size and structure of the emitting source. A worldwide effort is presently under way to implement stellar intensity interferometry on telescopes separated by long baselines and on future arrays of Cherenkov telescopes. We describe an experiment of this type, realized at the Asiago Observatory (Italy), in which we performed for the first time measurements of the correlation counting photon coincidences in post-processing by means of a single photon software correlator and exploiting entirely the quantum properties of the light emitted from a star. We successfully detected the temporal correlation of Vega at zero baseline and performed a measurement of the correlation on a projected baseline of $\sim$2 km. The average discrete degree of coherence at zero baseline for Vega is $< g^{(2)} > \, = 1.0034 \pm 0.0008$, providing a detection with a signal-to-noise ratio $S/N \gtrsim 4$. No correlation is detected over the km baseline. The measurements are consistent with the expected degree of spatial coherence for a source with the 3.3 mas angular diameter of Vega. The experience gained with the Asiago experiment will serve for future implementations of stellar intensity interferometry on long-baseline arrays of Cherenkov telescopes., Comment: 10 pages, 6 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society
Published: 2021
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