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907 results on '"Pawlak, M. A."'

1. Binarity at LOw Metallicity (BLOeM): I. a spectroscopic VLT monitoring survey of massive stars in the SMC

Author

Shenar, T., Bodensteiner, J., Sana, H., Crowther, P. A., Lennon, D. J., Abdul-Masih, M., Almeida, L. A., Backs, F., Berlanas, S. R., Bernini-Peron, M., Bestenlehner, J. M., Bowman, D. M., Bronner, V. A., Britavskiy, N., de Koter, A., de Mink, S. E., Deshmukh, K., Evans, C. J., Fabry, M., Gieles, M., Gilkis, A., González-Torà, G., Gräfener, G., Götberg, Y., Hawcroft, C., Hénault-Brunet, V., Herrero, A., Holgado, G., Janssens, S., Johnston, C., Josiek, J., Justham, S., Kalari, V. M., Katabi, Z. Z., Keszthelyi, Z., Klencki, J., Kubát, J., Kubátová, B., Langer, N., Lefever, R. R., Ludwig, B., Mackey, J., Mahy, L., Apellániz, J. Maíz, Mandel, I., Maravelias, G., Marchant, P., Menon, A., Najarro, F., Oskinova, L. M., Ovadia, R., Patrick, L. R., Pauli, D., Pawlak, M., Ramachandran, V., Renzo, M., Rocha, D. F., Sander, A. A. C., Sayada, T., Schneider, F. R. N., Schootemeijer, A., Schösser, E. C., Schürmann, C., Sen, K., Shahaf, S., Simón-Díaz, S., Stoop, M., van Loon, J. Th., Toonen, S., Tramper, F., Valli, R., van Son, L. A. C., Vigna-Gómez, A., Villaseñor, J. I., Vink, J. S., Wang, C., and Willcox, R.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

Surveys in the Milky Way and Large Magellanic Cloud revealed that the majority of massive stars will interact with companions during their lives. However, knowledge of the binary properties of massive stars at low metallicity, which approaches the conditions of the Early Universe, remains sparse. We present the Binarity at LOw Metallicity (BLOeM) campaign - an ESO large programme designed to obtain 25 epochs of spectroscopy for 929 massive stars in the SMC - the lowest metallicity conditions in which multiplicity is probed to date (Z = 0.2 Zsun). BLOeM will provide (i) the binary fraction, (ii) the orbital configurations of systems with periods P < 3 yr, (iii) dormant OB+BH binaries, and (iv) a legacy database of physical parameters of massive stars at low metallicity. The stars are observed with the LR02 setup of the giraffe instrument of the Very Large Telescope (3960-4570A, resolving power R=6200; typical signal-to-noise ratio S/N=70-100). This paper utilises the first 9 epochs obtained over a three-month time. We describe the survey and data reduction, perform a spectral classification of the stacked spectra, and construct a Hertzsprung-Russell diagram of the sample via spectral-type and photometric calibrations. The sample covers spectral types from O4 to F5, spanning the effective temperature and luminosity ranges 6.5

Published
2024

2. Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry

Author

Gaia Collaboration, Panuzzo, P., Mazeh, T., Arenou, F., Holl, B., Caffau, E., Jorissen, A., Babusiaux, C., Gavras, P., Sahlmann, J., Bastian, U., Wyrzykowski, Ł., Eyer, L., Leclerc, N., Bauchet, N., Bombrun, A., Mowlavi, N., Seabroke, G. M., Teyssier, D., Balbinot, E., Helmi, A., Brown, A. G. A., Vallenari, A., Prusti, T., de Bruijne, J. H. J., Barbier, A., Biermann, M., Creevey, O. L., Ducourant, C., Evans, D. W., Guerra, R., Hutton, A., Jordi, C., Klioner, S. A., Lammers, U., Lindegren, L., Luri, X., Mignard, F., Nicolas, C., Randich, S., Sartoretti, P., Smiljanic, R., Tanga, P., Walton, N. A., Aerts, C., Bailer-Jones, C. A. L., Cropper, M., Drimmel, R., Jansen, F., Katz, D., Lattanzi, M. G., Soubiran, C., Thévenin, F., van Leeuwen, F., Andrae, R., Audard, M., Bakker, J., Blomme, R., Castañeda, J., De Angeli, F., Fabricius, C., Fouesneau, M., Frémat, Y., Galluccio, L., Guerrier, A., Heiter, U., Masana, E., Messineo, R., Nienartowicz, K., Pailler, F., Riclet, F., Roux, W., Sordo, R., Gracia-Abril, G., Portell, J., Altmann, M., Benson, K., Berthier, J., Burgess, P. W., Busonero, D., Busso, G., Cacciari, C., Cánovas, H., Carrasco, J. M., Carry, B., Cellino, A., Cheek, N., Clementini, G., Damerdji, Y., Davidson, M., de Teodoro, P., Delchambre, L., Dell'Oro, A., Garcia, E. Fraile, Garabato, D., García-Lario, P., Haigron, R., Hambly, N. C., Harrison, D. L., Hatzidimitriou, D., Hernández, J., Hestroffer, D., Hodgkin, S. T., Jamal, S., de Fombelle, G. Jevardat, Jordan, S., Krone-Martins, A., Lanzafame, A. C., Löffler, W., Lorca, A., Marchal, O., Marrese, P. M., Moitinho, A., Muinonen, K., Campos, M. Nuñez, Oreshina-Slezak, I., Osborne, P., Pancino, E., Pauwels, T., Recio-Blanco, A., Riello, M., Rimoldini, L., Robin, A. C., Roegiers, T., Sarro, L. M., Schultheis, M., Smith, M., Sozzetti, A., Utrilla, E., van Leeuwen, M., Weingrill, K., Abbas, U., Ábrahám, P., Aramburu, A. Abreu, Ahmed, S., Altavilla, G., Álvarez, M. A., Anders, F., Anderson, R. I., Varela, E. Anglada, Antoja, T., Baig, S., Baines, D., Baker, S. G., Balaguer-Núñez, L., Balog, Z., Barache, C., Barros, M., Barstow, M. A., Bartolomé, S., Bashi, D., Bassilana, J. -L., Baudeau, N., Becciani, U., Bedin, L. R., Bellas-Velidis, I., Bellazzini, M., Beordo, W., Bernet, M., Bertolotto, C., Bertone, S., Bianchi, L., Binnenfeld, A., Blanco-Cuaresma, S., Bland-Hawthorn, J., Blazere, A., Boch, T., Bossini, D., Bouquillon, S., Bragaglia, A., Braine, J., Bratsolis, E., Breedt, E., Bressan, A., Brouillet, N., Brugaletta, E., Bucciarelli, B., Butkevich, A. G., Buzzi, R., Camut, A., Cancelliere, R., Cantat-Gaudin, T., Guilarte, D. Capilla, Carballo, R., Carlucci, T., Carnerero, M. I., Carretero, J., Carton, S., Casamiquela, L., Casey, A., Castellani, M., Castro-Ginard, A., Ceraj, L., Cesare, V., Charlot, P., Chaudet, C., Chemin, L., Chiavassa, A., Chornay, N., Chosson, D., Cooper, W. J., Cornez, T., Cowell, S., Crosta, M., Crowley, C., Reyes, M. Cruz, Dafonte, C., Ponte, M. Dal, David, M., de Laverny, P., De Luise, F., De March, R., De Ridder, J., de Torres, A., del Peloso, E. F., Delbo, M., Delgado, A., Delisle, J. -B., Demouchy, C., Denis, E., Dharmawardena, T. E., Di Giacomo, F., Diener, C., Distefano, E., Dolding, C., Dsilva, K., Enke, H., Fabre, C., Fabrizio, M., Faigler, S., Fatović, M., Fedorets, G., Fernández-Hernández, J., Fernique, P., Figueras, F., Fouron, C., Fragkoudi, F., Gai, M., Galinier, M., Garcia-Serrano, A., García-Torres, M., Garofalo, A., Gerlach, E., Geyer, R., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Gomboc, A., Gomez, A., González-Santamaría, I., Gosset, E., Granvik, M., Barrera, V. Gregori, Gutiérrez-Sánchez, R., Haywood, M., Helmer, A., Hidalgo, S. L., Hilger, T., Hobbs, D., Hottier, C., Huckle, H. E., Jiménez-Arranz, Ó., Campillo, J. Juaristi, Kaczmarek, Z., Kervella, P., Khanna, S., Kontizas, M., Kordopatis, G., Korn, A. J., Kóspál, Á, Kostrzewa-Rutkowska, Z., Kruszyńska, K., Kun, M., Lambert, S., Lanza, A. F., Lebreton, Y., Lebzelter, T., Leccia, S., Lecoutre, G., Liao, S., Liberato, L., Licata, E., Livanou, E., Lobel, A., López-Miralles, J., Loup, C., Madarász, M., Mahy, L., Mann, R. G., Manteiga, M., Marinoni, S., Marcellino, C. P., Marshall, D. J., Mascarenhas, D., Marchant, J. M., Lozano, J. Martín, Masip, A., Marconi, M., Pina, D. Marín, Polo, L. Martin, Martín-Fleitas, J. M., Mastrobuono-Battisti, A., McMillan, P. J., Meichsner, J. G. Marton, Merc, J., Messina, S., Millar, N. R., Mints, A., Mohamed, D., Molina, D., Molinaro, R., Monguió, M., Montegriffo, P., Monti, L., Mora, A., Morbidelli, R., Morris, D., Mudimadugula, R., Muraveva, T., Musella, I., Nagy, Z., Nardetto, N., Navarrete, C., Oh, S., Ordenovic, C., Orenstein, O., Pagani, C., Pagano, I., Palaversa, L., Palicio, P. A., Pallas-Quintela, L., Pawlak, M., Penttilä, A., Pesciullesi, P., Pinamonti, M., Plachy, E., Planquart, L., Plum, G., Poggio, E., Pourbaix, D., Price-Whelan, A. M., Pulone, L., Rabin, V., Rainer, M., Raiteri, C. M., Ramos, P., Ramos-Lerate, M., Ratajczak, M., Fiorentin, P. Re, Regibo, S., Reylé, C., Ripepi, V., Riva, A., Rix, H. -W., Rixon, G., Robert, G., Robichon, N., Robin, C., Romero-Gómez, M., Rowell, N., Mieres, D. Ruz, Rybicki, K. A., Sadowski, G., Sellés, A. Sagristà, Sanna, N., Santoveña, R., Sarasso, M., Sarmiento, M. H., Riera, C. Sarrate, Sciacca, E., Ségransan, D., Semczuk, M., Shahaf, S., Siebert, A., Slezak18, E., Smart, R. L., Snaith, O. N., Solano, E., Solitro, F., Souami, D., Souchay, J., Spitoni, E., Spoto, F., Squillante, L. A., Steele, I. A., Steidelmüller, H., Surdej, J., Szabados, L., Taris, F., Taylor, M. B., Teixeira, R., Tepper-Garcia, T., Thuillot, W., Tolomei, L., Tonello, N., Torra, F., Elipe, G. Torralba, Trabucchi, M., Trentin, E., Tsantaki, M., Turon, C., Ulla, A., Unger, N., Valtchanov, I., Vanel, O., Vecchiato, A., Vicente, D., Villar, E., Weiler, M., Zhao, H., Zorec, J., Zucker, S., Župić, A., and Zwitter, T.

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics
Abstract

Gravitational waves from black-hole merging events have revealed a population of extra-galactic BHs residing in short-period binaries with masses that are higher than expected based on most stellar evolution models - and also higher than known stellar-origin black holes in our Galaxy. It has been proposed that those high-mass BHs are the remnants of massive metal-poor stars. Gaia astrometry is expected to uncover many Galactic wide-binary systems containing dormant BHs, which may not have been detected before. The study of this population will provide new information on the BH-mass distribution in binaries and shed light on their formation mechanisms and progenitors. As part of the validation efforts in preparation for the fourth Gaia data release (DR4), we analysed the preliminary astrometric binary solutions, obtained by the Gaia Non-Single Star pipeline, to verify their significance and to minimise false-detection rates in high-mass-function orbital solutions. The astrometric binary solution of one source, Gaia BH3, implies the presence of a 32.70 \pm 0.82 M\odot BH in a binary system with a period of 11.6 yr. Gaia radial velocities independently validate the astrometric orbit. Broad-band photometric and spectroscopic data show that the visible component is an old, very metal-poor giant of the Galactic halo, at a distance of 590 pc. The BH in the Gaia BH3 system is more massive than any other Galactic stellar-origin BH known thus far. The low metallicity of the star companion supports the scenario that metal-poor massive stars are progenitors of the high-mass BHs detected by gravitational-wave telescopes. The Galactic orbit of the system and its metallicity indicate that it might belong to the Sequoia halo substructure. Alternatively, and more plausibly, it could belong to the ED-2 stream, which likely originated from a globular cluster that had been disrupted by the Milky Way., Comment: 23 pages, accepted fro publication in A&A Letters. New version with small fixes

Published
2024
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3. Gaia Early Data Release 3: The Galactic anticentre

Author

Gaia Collaboration, Antoja, T., McMillan, P., Kordopatis, G., Ramos, P., Helmi, A., Balbinot, E., Cantat-Gaudin, T., Chemin, L., Figueras, F., Jordi, C., Khanna, S., Romero-Gomez, M., Seabroke, G., Brown, A. G. A., Vallenari, A., Prusti, T., de Bruijne, J. H. J., Babusiaux, C., Biermann, M., Creevey, O. L., Evans, D. W., Eyer, L., Hutton, A., Jansen, F., Klioner, S. A., Lammers, U., Lindegren, L., Luri, X., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Soubiran, C., Walton, N. A., Arenou, F., Bailer-Jones, C. A. L., Bastian, U., Cropper, M., Drimmel, R., Katz, D., Lattanzi, M. G., van Leeuwen, F., Bakker, J., Castañeda, J., De Angeli, F., Ducourant, C., Fabricius, C., Fouesneau, M., Frémat, Y., Guerra, R., Guerrier, A., Guiraud, J., Piccolo, A. Jean-Antoine, Masana, E., Messineo, R., Mowlavi, N., Nicolas, C., Nienartowicz, K., Pailler, F., Panuzzo, P., Riclet, F., Roux, W., Sordo, R., Tanga, P., Thévenin, F., Gracia-Abril, G., Portell, J., Teyssier, D., Altmann, M., Andrae, R., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Brugaletta, E., Burgess, P. W., Busso, G., Carry, B., Cellino, A., Cheek, N., Clementini, G., Damerdji, Y., Davidson, M., Delchambre, L., Dell'Oro, A., Fernández-Hernández, J., Galluccio, L., García-Lario, P., Garcia-Reinaldos, M., González-Núñez, J., Gosset, E., Haigron, R., Halbwachs, J. -L., Hambly, N. C., Harrison, D. L., Hatzidimitriou, D., Heiter, U., Hernández, J., Hestroffer, D., Hodgkin, S. T., Holl, B., Janßen, K., de Fombelle, G. Jevardat, Jordan, S., Krone-Martins, A., Lanzafame, A. C., Löffler, W., Lorca, A., Manteiga, M., Marchal, O., Marrese, P. M., Moitinho, A., Mora, A., Muinonen, K., Osborne, P., Pancino, E., Pauwels, T., Recio-Blanco, A., Richards, P. J., Riello, M., Rimoldini, L., Robin, A. C., Roegiers, T., Rybizki, J., Sarro, L. M., Siopis, C., Smith, M., Sozzetti, A., Ulla, A., Utrilla, E., van Leeuwen, M., van Reeven, W., Abbas, U., Aramburu, A. Abreu, Accart, S., Aerts, C., Aguado, Ajaj, M., Altavilla, G., Álvarez, M. A., Cid-Fuentes, J. Álvarez, Alves, J., Anderson, J. J. R. I., Varela, E. Anglada, Audard, M., Baines, D., Baker, S. G., Balaguer-Núñez, L., Balog, Z., Barache, C., Barbato, D., Barros, M., Barstow, M. A., Bartolomé, S., Bassilana, J. -L., Bauchet, N., Baudesson-Stella, A., Becciani, U., Bellazzini, M., Bernet, M., Bertone, S., Bianchi, L., Blanco-Cuaresma, S., Boch, T., Bombrun, A., Bossini, D., Bouquillon, S., Bragaglia, A., Bramante, L., Breedt, E., Bressan, A., Brouillet, N., Bucciarelli, B., Burlacu, A., Busonero, D., Butkevich, A. G., Buzzi, R., Caffau, E., Cancelliere, R., Cánovas, H., Carballo, R., Carlucci, T., Carnerero, M. I, Carrasco, J. M., Casamiquela, L., Castellani, M., Castro-Ginard, A., Sampol, P. Castro, Chaoul, L., Charlot, P., Chiavassa, A., Cioni, M. -R. L., Comoretto, G., Cooper, W. J., Cornez, T., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Dafonte, C., Dapergolas, A., David, M., David, P., deLaverny, P., DeLuise, F., DeMarch, R., DeRidder, J., deSouza, R., de Teodoro, P., de Torres, A., del Peloso, E. F., del Pozo, E., Delgado, A., Delgado, H. E., Delisle, J. -B., Di Matteo, P., Diakite, S., Diener, C., Distefano, E., Dolding, C., Eappachen, D., Enke, H., Esquej, P., Fabre, C., Fabrizio, M., Faigler, S., Fedorets, G., Fernique, P., Fienga, A., Fouron, C., Fragkoudi, F., Fraile, E., Franke, F., Gai, M., Garabato, D., Garcia-Gutierrez, A., García-Torres, M., Garofalo, A., Gavras, P., Gerlach, E., Geyer, R., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Gomez, A., Gonzalez-Santamaria, I., González-Vidal, J. J., Granvik, M., Gutiérrez-Sánchez, R., Guy, L. P., Hauser, M., Haywood, M., Hidalgo, S. L., Hilger, T., Hładczuk, N., Hobbs, D., Holland, G., Huckle, H. E., Jasniewicz, G., Jonker, P. G., Campillo, J. Juaristi, Julbe, F., Karbevska, L., Kervella, P., Kochoska, A., Kontizas, M., Korn, A. J., Kostrzewa-Rutkowska, Z., Kruszyńska, K., Lambert, S., Lanza, A. F., Lasne, Y., Campion, J. -F. Le, Fustec, Y. Le, Lebreton, Y., Lebzelter, T., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Liao, S., Licata, E., Lindstrøm, H. E. P., Lister, T. A., Livanou, E., Lobel, A., Pardo, P. Madrero, Managau, S., Mann, R. G., Marchant, J. M., Marconi, M., Santos, M. M. S. Marcos, Marinoni, S., Marocco, F., Marshall, D. J., Polo, L. Martin, Martín-Fleitas, J. M., Masip, A., Massari, D., Mastrobuono-Battisti, A., Mazeh, T., Messina, S., Michalik, D., Millar, N. R., Mints, A., Molina, D., Molinaro, R., Molnár, L., Montegriffo, P., Mor, R., Morbidelli, R., Morel, T., Morris, D., Mulone, A. F., Munoz, D., Muraveva, T., Murphy, C. P., Musella, I., Noval, L., Ordénovic, C., Orrù, G., Osinde, J., Pagani, C., Pagano, I., Palaversa, L., Palicio, P. A., Panahi, A., Pawlak, M., Esteller, X. Peñalosa, Penttilä, A., Piersimoni, A. M., Pineau, F. -X., Plachy, E., Plum, G., Poggio, E., Poretti, E., Poujoulet, E., Prša, A., Pulone, L., Racero, E., Ragaini, S., Rainer, M., Raiteri, C. M., Rambaux, N., Ramos-Lerate, M., Fiorentin, P. Re, Regibo, S., Reylé, C., Ripepi, V., Riva, A., Rixon, G., Robichon, N., Robin, C., Roelens, M., Rohrbasser, L., Rowell, N., Royer, F., Rybicki, K. A., Sadowski, G., Sellés, A. Sagristà, Sahlmann, J., Salgado, J., Salguero, E., Samaras, N., Gimenez, V. Sanchez, Sanna, N., Santoveña, R., Sarasso, M., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Ségransan, D., Semeux, D., Siddiqui, H. I., Siebert, A., Siltala, L., Slezak, E., Smart, R. L., Solano, E., Solitro, F., Souami, D., Souchay, J., Spagna, A., Spoto, F., Steele, I. A., Steidelmüller, H., Stephenson, C. A., Süveges, M., Szabados, L., Szegedi-Elek, E., Taris, F., Tauran, G., Taylor, M. B., Teixeira, R., Thuillot, W., Tonello, N., Torra, F., Torra, J., Turon, C., Unger, N., Vaillant, M., van Dillen, E., Vanel, O., Vecchiato, A., Viala, Y., Vicente, D., Voutsinas, S., Weiler, M., Wevers, T., Wyrzykowski, L., Yoldas, A., Yvard, P., Zhao, H., Zorec, J., Zucker, S., Zurbach, C., and Zwitter, T.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We aim to demonstrate the scientific potential of the Gaia Early Data Release 3 (EDR3) for the study of the Milky Way structure and evolution. We used astrometric positions, proper motions, parallaxes, and photometry from EDR3 to select different populations and components and to calculate the distances and velocities in the direction of the anticentre. We explore the disturbances of the current disc, the spatial and kinematical distributions of early accreted versus in-situ stars, the structures in the outer parts of the disc, and the orbits of open clusters Berkeley 29 and Saurer 1. We find that: i) the dynamics of the Galactic disc are very complex with vertical asymmetries, and new correlations, including a bimodality with disc stars with large angular momentum moving vertically upwards from below the plane, and disc stars with slightly lower angular momentum moving preferentially downwards; ii) we resolve the kinematic substructure (diagonal ridges) in the outer parts of the disc for the first time; iii) the red sequence that has been associated with the proto-Galactic disc that was present at the time of the merger with Gaia-Enceladus-Sausage is currently radially concentrated up to around 14 kpc, while the blue sequence that has been associated with debris of the satellite extends beyond that; iv) there are density structures in the outer disc, both above and below the plane, most probably related to Monoceros, the Anticentre Stream, and TriAnd, for which the Gaia data allow an exhaustive selection of candidate member stars and dynamical study; and v) the open clusters Berkeley~29 and Saurer~1, despite being located at large distances from the Galactic centre, are on nearly circular disc-like orbits. We demonstrate how, once again, the Gaia are crucial for our understanding of the different pieces of our Galaxy and their connection to its global structure and history., Comment: Gaia EDR3 performance verification paper, version 2 closer to published version in A&A, complete list of authors

Published
2021
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4. Gaia Early Data Release 3: The Gaia Catalogue of Nearby Stars

Author

Gaia Collaboration, Smart, R. L., Sarro, L. M., Rybizki, J., Reylé, C., Robin, A. C., Hambly, N. C., Abbas, U., Barstow, M. A., de Bruijne, J. H. J., Bucciarelli, B., Carrasco, J. M., Cooper, W. J., Hodgkin, S. T., Masana, E., Michalik, D., Sahlmann, J., Sozzetti, A., Brown, A. G. A., Vallenari, A., Prusti, T., Babusiaux, C., Biermann, M., Creevey, O. L., Evans, D. W., Eyer, L., Hutton, A., Jansen, F., Jordi, C., Klioner, S. A., Lammers, U., Lindegren, L., Luri, X., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Soubiran, C., Walton, N. A., Arenou, F., Bailer-Jones, C. A. L., Bastian, U., Cropper, M., Drimmel, R., Katz, D., Lattanzi, M. G., van Leeuwen, F., Bakker, J., Castañeda, J., De Angeli, F., Ducourant, C., Fabricius, C., Fouesneau, M., Frémat, Y., Guerra, R., Guerrier, A., Guiraud, J., Piccolo, A. Jean-Antoine, Messineo, R., Mowlavi, N., Nicolas, C., Nienartowicz, K., Pailler, F., Panuzzo, P., Riclet, F., Roux, W., Seabroke, G. M., Sordo, R., Tanga, P., Thévenin, F., Gracia-Abril, G., Portell, J., Teyssier, D., Altmann, M., Andrae, R., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Brugaletta, E., Burgess, P. W., Busso, G., Carry, B., Cellino, A., Cheek, N., Clementini, G., Damerdji, Y., Davidson, M., Delchambre, L., Dell'Oro, A., Fernández-Hernández, J., Galluccio, L., García-Lario, P., Garcia-Reinaldos, M., González-Núñez, J., Gosset, E., Haigron, R., Halbwachs, J. -L., Harrison, D. L., Hatzidimitriou, D., Heiter, U., Hernández, J., Hestroffer, D., Holl, B., Janßen, K., de Fombelle, G. Jevardat, Jordan, S., Krone-Martins, A., Lanzafame, A. C., Löffler, W., Lorca, A., Manteiga, M., Marchal, O., Marrese, P. M., Moitinho, A., Mora, A., Muinonen, K., Osborne, P., Pancino, E., Pauwels, T., Recio-Blanco, A., Richards, P. J., Riello, M., Rimoldini, L., Roegiers, T., Siopis, C., Smith, M., Ulla, A., Utrilla, E., van Leeuwen, M., van Reeven, W., Aramburu, A. Abreu, Accart, S., Aerts, C., Aguado, J. J., Ajaj, M., Altavilla, G., Álvarez, M. A., Cid-Fuentes, J. Álvarez, Alves, J., Anderson, R. I., Varela, E. Anglada, Antoja, T., Audard, M., Baines, D., Baker, S. G., Balaguer-Núñez, L., Balbinot, E., Balog, Z., Barache, C., Barbato, D., Barros, M., Bartolomé, S., Bassilana, J. -L., Bauchet, N., Baudesson-Stella, A., Becciani, U., Bellazzini, M., Bernet, M., Bertone, S., Bianchi, L., Blanco-Cuaresma, S., Boch, T., Bombrun, A., Bossini, D., Bouquillon, S., Bragaglia, A., Bramante, L., Breedt, E., Bressan, A., Brouillet, N., Burlacu, A., Busonero, D., Butkevich, A. G., Buzzi, R., Caffau, E., Cancelliere, R., Cánovas, H., Cantat-Gaudin, T., Carballo, R., Carlucci, T., Carnerero, M. I, Casamiquela, L., Castellani, M., Castro-Ginard, A., Sampol, P. Castro, Chaoul, L., Charlot, P., Chemin, L., Chiavassa, A., Cioni, M. -R. L., Comoretto, G., Cornez, T., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Dafonte, C., Dapergolas, A., David, M., David, P., de Laverny, P., De Luise, F., De March, R., De Ridder, J., de Souza, R., de Teodoro, P., de Torres, A., del Peloso, E. F., del Pozo, E., Delgado, A., Delgado, H. E., Delisle, J. -B., Di Matteo, P., Diakite, S., Diener, C., Distefano, E., Dolding, C., Eappachen, D., Edvardsson, B., Enke, H., Esquej, P., Fabre, C., Fabrizio, M., Faigler, S., Fedorets, G., Fernique, P., Fienga, A., Figueras, F., Fouron, C., Fragkoudi, F., Fraile, E., Franke, F., Gai, M., Garabato, D., Garcia-Gutierrez, A., García-Torres, M., Garofalo, A., Gavras, P., Gerlach, E., Geyer, R., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Gomel, R., Gomez, A., Gonzalez-Santamaria, I., González-Vidal, J. J., Granvik, M., Gutiérrez-Sánchez, R., Guy, L. P., Hauser, M., Haywood, M., Helmi, A., Hidalgo, S. L., Hilger, T., Hładczuk, N., Hobbs, D., Holland, G., Huckle, H. E., Jasniewicz, G., Jonker, P. G., Campillo, J. Juaristi, Julbe, F., Karbevska, L., Kervella, P., Khanna, S., Kochoska, A., Kontizas, M., Kordopatis, G., Korn, A. J., Kostrzewa-Rutkowska, Z., Kruszyńska, K., Lambert, S., Lanza, A. F., Lasne, Y., Campion, J. -F. Le, Fustec, Y. Le, Lebreton, Y., Lebzelter, T., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Liao, S., Licata, E., Lindstrøm, H. E. P., Lister, T. A., Livanou, E., Lobel, A., Pardo, P. Madrero, Managau, S., Mann, R. G., Marchant, J. M., Marconi, M., Santos, M. M. S. Marcos, Marinoni, S., Marocco, F., Marshall, D. J., Polo, L. Martin, Martín-Fleitas, J. M., Masip, A., Massari, D., Mastrobuono-Battisti, A., Mazeh, T., McMillan, P. J., Messina, S., Millar, N. R., Mints, A., Molina, D., Molinaro, R., Molnár, L., Montegriffo, P., Mor, R., Morbidelli, R., Morel, T., Morris, D., Mulone, A. F., Munoz, D., Muraveva, T., Murphy, C. P., Musella, I., Noval, L., Ordénovic, C., Orrù, G., Osinde, J., Pagani, C., Pagano, I., Palaversa, L., Palicio, P. A., Panahi, A., Pawlak, M., Esteller, X. Peñalosa, Penttilä, A., Piersimoni, A. M., Pineau, F. -X., Plachy, E., Plum, G., Poggio, E., Poretti, E., Poujoulet, E., Prša, A., Pulone, L., Racero, E., Ragaini, S., Rainer, M., Raiteri, C. M., Rambaux, N., Ramos, P., Ramos-Lerate, M., Fiorentin, P. Re, Regibo, S., Ripepi, V., Riva, A., Rixon, G., Robichon, N., Robin, C., Roelens, M., Rohrbasser, L., Romero-Gómez, M., Rowell, N., Royer, F., Rybicki, K. A., Sadowski, G., Sellés, A. Sagristà, Salgado, J., Salguero, E., Samaras, N., Gimenez, V. Sanchez, Sanna, N., Santoveña, R., Sarasso, M., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Ségransan, D., Semeux, D., Shahaf, S., Siddiqui, H. I., Siebert, A., Siltala, L., Slezak, E., Solano, E., Solitro, F., Souami, D., Souchay, J., Spagna, A., Spoto, F., Steele, I. A., Steidelmüller, H., Stephenson, C. A., Süveges, M., Szabados, L., Szegedi-Elek, E., Taris, F., Tauran, G., Taylor, M. B., Teixeira, R., Thuillot, W., Tonello, N., Torra, F., Torra, J., Turon, C., Unger, N., Vaillant, M., van Dillen, E., Vanel, O., Vecchiato, A., Viala, Y., Vicente, D., Voutsinas, S., Weiler, M., Wevers, T., Wyrzykowski, L., Yoldas, A., Yvard, P., Zhao, H., Zorec, J., Zucker, S., Zurbach, C., and Zwitter, T.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

We produce a clean and well-characterised catalogue of objects within 100\,pc of the Sun from the \G\ Early Data Release 3. We characterise the catalogue through comparisons to the full data release, external catalogues, and simulations. We carry out a first analysis of the science that is possible with this sample to demonstrate its potential and best practices for its use. The selection of objects within 100\,pc from the full catalogue used selected training sets, machine-learning procedures, astrometric quantities, and solution quality indicators to determine a probability that the astrometric solution is reliable. The training set construction exploited the astrometric data, quality flags, and external photometry. For all candidates we calculated distance posterior probability densities using Bayesian procedures and mock catalogues to define priors. Any object with reliable astrometry and a non-zero probability of being within 100\,pc is included in the catalogue. We have produced a catalogue of \NFINAL\ objects that we estimate contains at least 92\% of stars of stellar type M9 within 100\,pc of the Sun. We estimate that 9\% of the stars in this catalogue probably lie outside 100\,pc, but when the distance probability function is used, a correct treatment of this contamination is possible. We produced luminosity functions with a high signal-to-noise ratio for the main-sequence stars, giants, and white dwarfs. We examined in detail the Hyades cluster, the white dwarf population, and wide-binary systems and produced candidate lists for all three samples. We detected local manifestations of several streams, superclusters, and halo objects, in which we identified 12 members of \G\ Enceladus. We present the first direct parallaxes of five objects in multiple systems within 10\,pc of the Sun., Comment: 45 Pages, 39 figures in main part and 18 in appendix, tables on CDS

Published
2020
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5. Gaia Early Data Release 3: Acceleration of the solar system from Gaia astrometry

Author

Gaia Collaboration, Klioner, S. A., Mignard, F., Lindegren, L., Bastian, U., McMillan, P. J., Hernández, J., Hobbs, D., Ramos-Lerate, M., Biermann, M., Bombrun, A., de Torres, A., Gerlach, E., Geyer, R., Hilger, T., Lammers, U., Steidelmüller, H., Stephenson, C. A., Brown, A. G. A., Vallenari, A., Prusti, T., de Bruijne, J. H. J., Babusiaux, C., Creevey, O. L., Evans, D. W., Eyer, L., Hutton, A., Jansen, F., Jordi, C., Luri, X., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Soubiran, C., Walton, N. A., Arenou, F., Bailer-Jones, C. A. L., Cropper, M., Drimmel, R., Katz, D., Lattanzi, M. G., van Leeuwen, F., Bakker, J., Castañeda, J., De Angeli, F., Ducourant, C., Fabricius, C., Fouesneau, M., Frémat, Y., Guerra, R., Guerrier, A., Guiraud, J., Piccolo, A. Jean-Antoine, Masana, E., Messineo, R., Mowlavi, N., Nicolas, C., Nienartowicz, K., Pailler, F., Panuzzo, P., Riclet, F., Roux, W., Seabroke, G. M., Sordo, R., Tanga, P., Thévenin, F., Gracia-Abril, G., Portell, J., Teyssier, D., Altmann, M., Andrae, R., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Brugaletta, E., Burgess, P. W., Busso, G., Carry, B., Cellino, A., Cheek, N., Clementini, G., Damerdji, Y., Davidson, M., Delchambre, L., Dell'Oro, A., Fernández-Hernández, J., Galluccio, L., García-Lario, P., Garcia-Reinaldos, M., González-Núñez, J., Gosset, E., Haigron, R., Halbwachs, J. -L., Hambly, N. C., Harrison, D. L., Hatzidimitriou, D., Heiter, U., Hestroffer, D., Hodgkin, S. T., Holl, B., Janßen, K., de Fombelle, G. Jevardat, Jordan, S., Krone-Martins, A., Lanzafame, A. C., Löffler, W., Lorca, A., Manteiga, M., Marchal, O., Marrese, P. M., Moitinho, A., Mora, A., Muinonen, K., Osborne, P., Pancino, E., Pauwels, T., Recio-Blanco, A., Richards, P. J., Riello, M., Rimoldini, L., Robin, A. C., Roegiers, T., Rybizki, J., Sarro, L. M., Siopis, C., Smith, M., Sozzetti, A., Ulla, A., Utrilla, E., van Leeuwen, M., van Reeven, W., Abbas, U., Aramburu, A. Abreu, Accart, S., Aerts, C., Aguado, J. J., Ajaj, M., Altavilla, G., Álvarez, M. A., Cid-Fuentes, J. Álvarez, Alves, J., Anderson, R. I., Varela, E. Anglada, Antoja, T., Audard, M., Baines, D., Baker, S. G., Balaguer-Nú\-nez, L., Balbinot, E., Balog, Z., Barache, C., Barbato, D., Barros, M., Barstow, M. A., Bartolomé, S., Bassilana, J. -L., Bauchet, N., Baudesson-Stella, A., Becciani, U., Bellazzini, M., Bernet, M., Bertone, S., Bianchi, L., Blanco-Cuaresma, S., Boch, T., Bossini, D., Bouquillon, S., Bramante, L., Breedt, E., Bressan, A., Brouillet, N., Bucciarelli, B., Burlacu, A., Busonero, D., Butkevich, A. G., Buzzi, R., Caffau, E., Cancelliere, R., Cánovas, H., Cantat-Gaudin, T., Carballo, R., Carlucci, T., Carnerero, M. I, Carrasco, J. M., Casamiquela, L., Castellani, M., Castro-Ginard, A., Sampol, P. Castro, Chaoul, L., Charlot, P., Chemin, L., Chiavassa, A., Comoretto, G., Cooper, W. J., Cornez, T., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Dafonte, C., Dapergolas, A., David, M., David, P., de Laverny, P., De Luise, F., De March, R., De Ridder, J., de Souza, R., de Teodoro, P., del Peloso, E. F., del Pozo, E., Delgado, A., Delgado, H. E., Delisle, J. -B., Di Matteo, P., Diakite, S., Diener, C., Distefano, E., Dolding, C., Eappachen, D., Enke, H., Esquej, P., Fabre, C., Fabrizio, M., Faigler, S., Fedorets, G., Fernique, P., Fienga, A., Figueras, F., Fouron, C., Fragkoudi, F., Fraile, E., Franke, F., Gai, M., Garabato, D., Garcia-Gutierrez, A., García-Torres, M., Garofalo, A., Gavras, P., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Gomez, A., Gonzalez-Santamaria, I., González-Vidal, J. J., Granvik, M., Gutiérrez-Sánchez, R., Guy, L. P., Hauser, M., Haywood, M., Helmi, A., Hidalgo, S. L., Hładczuk, N., Holland, G., Huckle, H. E., Jasniewicz, G., Jonker, P. G., Campillo, J. Juaristi, Julbe, F., Karbevska, L., Kervella, P., Khanna, S., Kochoska, A., Kordopatis, G., Korn, A. J., Kostrzewa-Rutkowska, Z., Kruszyńska, K., Lambert, S., Lanza, A. F., Lasne, Y., Campion, J. -F. Le, Fustec, Y. Le, Lebreton, Y., Lebzelter, T., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Liao, S., Licata, E., Lindstrøm, H. E. P., Lister, T. A., Livanou, E., Lobel, A., Pardo, P. Madrero, Managau, S., Mann, R. G., Marchant, J. M., Marconi, M., Santos, M. M. S. Marcos, Marinoni, S., Marocco, F., Marshall, D. J., Polo, L. Martin, Martín-Fleitas, J. M., Masip, A., Massari, D., Mastrobuono-Battisti, A., Mazeh, T., Messina, S., Michalik, D., Millar, N. R., Mints, A., Molina, D., Molinaro, R., Molnár, L., Montegriffo, P., Mor, R., Morbidelli, R., Morel, T., Morris, D., Mulone, A. F., Munoz, D., Muraveva, T., Murphy, C. P., Musella, I., Noval, L., Ordénovic, C., Orrù, G., Osinde, J., Pagani, C., Pagano, I., Palaversa, L., Palicio, P. A., Panahi, A., Pawlak, M., Esteller, X. Pe\-nalosa, Penttilä, A., Piersimoni, A. M., Pineau, F. -X., Plachy, E., Plum, G., Poggio, E., Poretti, E., Poujoulet, E., Prša, A., Pulone, L., Racero, E., Ragaini, S., Rainer, M., Raiteri, C. M., Rambaux, N., Ramos, P., Fiorentin, P. Re, Regibo, S., Reylé, C., Ripepi, V., Riva, A., Rixon, G., Robichon, N., Robin, C., Roelens, M., Rohrbasser, L., Romero-Gómez, M., Rowell, N., Royer, F., Rybicki, K. A., Sadowski, G., Sellés, A. Sagristà, Sahlmann, J., Salgado, J., Salguero, E., Samaras, N., Gimenez, V. Sanchez, Sanna, N., Santoveña, R., Sarasso, M., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Ségransan, D., Semeux, D., Siddiqui, H. I., Siebert, A., Siltala, L., Slezak, E., Smart, R. L., Solano, E., Solitro, F., Souami, D., Souchay, J., Spagna, A., Spoto, F., Steele, I. A., Süveges, M., Szabados, L., Szegedi-Elek, E., Taris, F., Tauran, G., Taylor, M. B., Teixeira, R., Thuillot, W., Tonello, N., Torra, F., Torray, J., Turon, C., Unger, N., Vaillant, M., van Dillen, E., Vanel, O., Vecchiato, A., Viala, Y., Vicente, D., Voutsinas, S., Weiler, M., Wevers, T., Wyrzykowski, Ł., Yoldas, A., Yvard, P., Zhao, H., Zorec, J., Zucker, S., Zurbach, C., and Zwitter, T.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Context. Gaia Early Data Release 3 (Gaia EDR3) provides accurate astrometry for about 1.6 million compact (QSO-like) extragalactic sources, 1.2 million of which have the best-quality five-parameter astrometric solutions. Aims. The proper motions of QSO-like sources are used to reveal a systematic pattern due to the acceleration of the solar system barycentre with respect to the rest frame of the Universe. Apart from being an important scientific result by itself, the acceleration measured in this way is a good quality indicator of the Gaia astrometric solution. Methods. The effect of the acceleration is obtained as a part of the general expansion of the vector field of proper motions in Vector Spherical Harmonics (VSH). Various versions of the VSH fit and various subsets of the sources are tried and compared to get the most consistent result and a realistic estimate of its uncertainty. Additional tests with the Gaia astrometric solution are used to get a better idea on possible systematic errors in the estimate. Results. Our best estimate of the acceleration based on Gaia EDR3 is $(2.32 \pm 0.16) \times 10^{-10}$ m s${}^{-2}$ (or $7.33 \pm 0.51$ km s$^{-1}$ Myr${}^{-1}$) towards $\alpha = 269.1^\circ \pm 5.4^\circ$, $\delta = -31.6^\circ \pm 4.1^\circ$, corresponding to a proper motion amplitude of $5.05 \pm 0.35$ $\mu$as yr${}^{-1}$. This is in good agreement with the acceleration expected from current models of the Galactic gravitational potential. We expect that future Gaia data releases will provide estimates of the acceleration with uncertainties substantially below 0.1 $\mu$as yr${}^{-1}$., Comment: A&A, accepted

Published
2020
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6. Gaia Early Data Release 3: Structure and properties of the Magellanic Clouds

Author

Gaia Collaboration, Luri, X., Chemin, L., Clementini, G., Delgado, H. E., McMillan, P. J., Romero-Gómez, M., Balbinot, E., Castro-Ginard, A., Mor, R., Ripepi, V., Sarro, L. M., Cioni, M. -R. L., Fabricius, C., Garofalo, A., Helmi, A., Muraveva, T., Brown, A. G. A., Vallenari, A., Prusti, T., de, J. H. J., Babusiaux, C., Biermann, M., Creevey, O. L., Evans, D. W., Eyer, L., Hutton, A., Jansen, F., Jordi, C., Klioner, S. A., Lammers, U., Lindegren, L., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Soubiran, C., Walton, N. A., Arenou, F., Bailer-Jones, C. A. L., Bastian, U., Cropper, M., Drimmel, R., Katz, D., Lattanzi, M. G., van Leeuwen, F., Bakker, J., Castañeda, J., De, F., Ducourant, C., Fouesneau, M., Frémat, Y., Guerra, R., Guerrier, A., Guiraud, J., Jean-Antoine, A., Masana, E., Messineo, R., Mowlavi, N., Nicolas, C., Nienartowicz, K., Pailler, F., Panuzzo, P., Riclet, F., Roux, W., Seabroke, G. M., Sordo, R., Tanga, P., Thévenin, F., Gracia-Abril, G., Portell, J., Teyssier, D., Altmann, M., Andrae, R., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Brugaletta, E., Burgess, P. W., Busso, G., Carry, B., Cellino, A., Cheek, N., Damerdji, Y., Davidson, M., Delchambre, L., Dell'Oro, A., Fernández-Hernández, J., Galluccio, L., García-Lario, P., Garcia-Reinaldos, M., González-Núñez, J., Gosset, E., Haigron, R., Halbwachs, J. -L., Hambly, N. C., Harrison, D. L., Hatzidimitriou, D., Heiter, U., Hernández, J., Hestroffer, D., Hodgkin, S. T., Holl, B., Janßen, K., de Fombelle, G. Jevardat, Jordan, S., Krone-Martins, A., Lanzafame, A. C., Löffler, W., Lorca, A., Manteiga, M., Marchal, O., Marrese, P. M., Moitinho, A., Mora, A., Muinonen, K., Osborne, P., Pancino, E., Pauwels, T., Recio-Blanco, A., Richards, P. J., Riello, M., Rimoldini, L., Robin, A. C., Roegiers, T., Rybizki, J., Siopis, C., Smith, M., Sozzetti, A., Ulla, A., Utrilla, E., van Leeuwen, M., van Reeven, W., Abbas, U., Abreu, A., Accart, S., Aerts, C., Aguado, J. J., Ajaj, M., Altavilla, G., Álvarez, M. A., Cid-Fuentes, J. Álvarez, Alves, J., Anderson, R. I., Varela, E. Anglada, Antoja, T., Audard, M., Baines, D., Baker, S. G., Balaguer-Núñez, L., Balog, Z., Barache, C., Barbato, D., Barros, M., Barstow, M. A., Bartolomé, S., Bassilana, J. -L., Bauchet, N., Baudesson-Stella, A., Becciani, U., Bellazzini, M., Bernet, M., Bertone, S., Bianchi, L., Blanco-Cuaresma, S., Boch, T., Bombrun, A., Bossini, D., Bouquillon, S., Bragaglia, A., Bramante, L., Breedt, E., Bressan, A., Brouillet, N., Bucciarelli, B., Burlacu, A., Busonero, D., Butkevich, A. G., Buzzi, R., Caffau, E., Cancelliere, R., Cánovas, H., Cantat-Gaudin, T., Carballo, R., Carlucci, T., Carnerero, M. I, Carrasco, J. M., Casamiquela, L., Castellani, M., Sampol, P. Castro, Chaoul, L., Charlot, P., Chiavassa, A., Comoretto, G., Cooper, W. J., Cornez, T., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Dafonte, C., Dapergolas, A., David, M., David, P., de Laverny, P., De Luise, F., De March, R., De Ridder, J., de Souza, R., de Teodoro, P., de Torres, A., del Peloso, E. F., del Pozo, E., Delgado, A., Delisle, J. -B., Di Matteo, P., Diakite, S., Diener, C., Distefano, E., Dolding, C., Eappachen, D., Enke, H., Esquej, P., Fabre, C., Fabrizio, M., Faigler, S., Fedorets, G., Fernique, P., Fienga, A., Figueras, F., Fouron, C., Fragkoudi, F., Fraile, E., Franke, F., Gai, M., Garabato, D., Garcia-Gutierrez, A., García-Torres, M., Gavras, P., Gerlach, E., Geyer, R., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Gomez, A., Gonzalez-Santamaria, I., González-Vidal, J. J., Granvik, M., Gutiérrez-Sánchez, R., Guy, L. P., Hauser, M., Haywood, M., Hidalgo, S. L., Hilger, T., Hładczuk, N., Hobbs, D., Holland, G., Huckle, H. E., Jasniewicz, G., Jonker, P. G., Juaristi, J., Julbe, F., Karbevska, L., Kervella, P., Khanna, S., Kochoska, A., Kontizas, M., Kordopatis, G., Korn, A. J., Kostrzewa-Rutkowska, Z., Kruszyńska, K., Lambert, S., Lanza, A. F., Lasne, Y., Campion, J. -F. Le, Fustec, Y. Le, Lebreton, Y., Lebzelter, T., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Liao, S., Licata, E., Lindstrøm, H. E. P., Lister, T. A., Livanou, E., Lobel, A., Madrero, P., Managau, S., Mann, R. G., Marchant, J. M., Marconi, M., Marcos, M. M. S., Marinoni, S., Marocco, F., Marshall, D. J., Polo, L. Martin, Martín-Fleitas, J. M., Masip, A., Massari, D., Mastrobuono-Battisti, A., Mazeh, T., Messina, S., Michalik, D., Millar, N. R., Mints, A., Molina, D., Molinaro, R., Molnár, L., Montegriffo, P., Morbidelli, R., Morel, T., Morris, D., Mulone, A. F., Munoz, D., Murphy, C. P., Musella, I., Noval, L., Ordénovic, C., Orrù, G., Osinde, J., Pagani, C., Pagano, I., Palaversa, L., Palicio, P. A., Panahi, A., Pawlak, M., Peñalosa, X., Penttilä, A., Piersimoni, A. M., Pineau, F. -X., Plachy, E., Plum, G., Poggio, E., Poretti, E., Poujoulet, E., Prša, A., Pulone, L., Racero, E., Ragaini, S., Rainer, M., Raiteri, C. M., Rambaux, N., Ramos, P., Ramos-Lerate, M., Re, P., Regibo, S., Reylé, C., Riva, A., Rixon, G., Robichon, N., Robin, C., Roelens, M., Rohrbasser, L., Rowell, N., Royer, F., Rybicki, K. A., Sadowski, G., Sagristà, A., Sahlmann, J., Salgado, J., Salguero, E., Samaras, N., Sanchez, V., Sanna, N., Santoveña, R., Sarasso, M., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Ségransan, D., Semeux, D., Siddiqui, H. I., Siebert, A., Siltala, L., Slezak, E., Smart, R. L., Solano, E., Solitro, F., Souami, D., Souchay, J., Spagna, A., Spoto, F., Steele, I. A., Steidelmüller, H., Stephenson, C. A., Süveges, M., Szabados, L., Szegedi-Elek, E., Taris, F., Tauran, G., Taylor, M. B., Teixeira, R., Thuillot, W., Tonello, N., Torra, F., Torra, J., Turon, C., Unger, N., Vaillant, M., van, E., Vanel, O., Vecchiato, A., Viala, Y., Vicente, D., Voutsinas, S., Weiler, M., Wevers, T., Wyrzykowski, Ł., Yoldas, A., Yvard, P., Zhao, H., Zorec, J., Zucker, S., Zurbach, C., and Zwitter, T.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We compare the Gaia DR2 and Gaia EDR3 performances in the study of the Magellanic Clouds and show the clear improvements in precision and accuracy in the new release. We also show that the systematics still present in the data make the determination of the 3D geometry of the LMC a difficult endeavour; this is at the very limit of the usefulness of the Gaia EDR3 astrometry, but it may become feasible with the use of additional external data. We derive radial and tangential velocity maps and global profiles for the LMC for the several subsamples we defined. To our knowledge, this is the first time that the two planar components of the ordered and random motions are derived for multiple stellar evolutionary phases in a galactic disc outside the Milky Way, showing the differences between younger and older phases. We also analyse the spatial structure and motions in the central region, the bar, and the disc, providing new insights into features and kinematics. Finally, we show that the Gaia EDR3 data allows clearly resolving the Magellanic Bridge, and we trace the density and velocity flow of the stars from the SMC towards the LMC not only globally, but also separately for young and evolved populations. This allows us to confirm an evolved population in the Bridge that is slightly shift from the younger population. Additionally, we were able to study the outskirts of both Magellanic Clouds, in which we detected some well-known features and indications of new ones., Comment: This paper is part of the "demonstration papers" released with Gaia EDR3: https://www.cosmos.esa.int/web/gaia/earlydr3

Published
2020
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7. Gaia Early Data Release 3: Summary of the contents and survey properties

Author

Gaia Collaboration, Brown, A. G. A, Vallenari, A., Prusti, T., de Bruijne, J. H. J., Babusiaux, C., Biermann, M., Creevey, O. L., Evans, D. W., Eyer, L., Hutton, A., Jansen, F., Jordi, C., Klioner, S. A., Lammers, U., Lindegren, L., Luri, X., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Soubiran, C., Walton, N. A., Arenou, F., Bailer-Jones, C. A. L., Bastian, U., Cropper, M., Drimmel, R., Katz, D., Lattanzi, M. G., van Leeuwen, F., Bakker, J., Cacciari, C., Castañeda, J., De Angeli, F., Ducourant, C., Fabricius, C., Fouesneau, M., Frémat, Y., Guerra, R., Guerrier, A., Guiraud, J., Piccolo, A. Jean-Antoine, Masana, E., Messineo, R., Mowlavi, N., Nicolas, C., Nienartowicz, K., Pailler, F., Panuzzo, P., Riclet, F., Roux, W., Seabroke, G. M., Sordo, R., Tanga, P., Thévenin, F., Gracia-Abril, G., Portell, J., Teyssier, D., Altmann, M., Andrae, R., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Brugaletta, E., Burgess, P. W., Busso, G., Carry, B., Cellino, A., Cheek, N., Clementini, G., Damerdji, Y., Davidson, M., Delchambre, L., Dell'Oro, A., Fernández-Hernández, J., Galluccio, L., García-Lario, P., Garcia-Reinaldos, M., González-Núñez, J., Gosset, E., Haigron, R., Halbwachs, J. -L., Hambly, N. C., Harrison, D. L., Hatzidimitriou, D., Heiter, U., Hernández, J., Hestroffer, D., Hodgkin, S. T., Holl, B., Janßen, K., de Fombelle, G. Jevardat, Jordan, S., Krone-Martins, A., Lanzafame, A. C., o}ffler, W. L\"{, Lorca, A., Manteiga, M., Marchal, O., Marrese, P. M., Moitinho, A., Mora, A., Muinonen, K., Osborne, P., Pancino, E., Pauwels, T., Petit, J. -M., Recio-Blanco, A., Richards, P. J., Riello, M., Rimoldini, L., Robin, A. C., Roegiers, T., Rybizki, J., Sarro, L. M., Siopis, C., Smith, M., Sozzetti, A., Ulla, A., Utrilla, E., van Leeuwen, M., van Reeven, W., Abbas, U., Aramburu, A. Abreu, Accart, S., Aerts, C., Aguado, J. J., Ajaj, M., Altavilla, G., Álvarez, M. A., Cid-Fuentes, J. Álvarez, Alves, J., Anderson, R. I., Varela, E. Anglada, Antoja, T., Audard, M., Baines, D., Baker, S. G., Balaguer-Núñez, L., Balbinot, E., Balog, Z., Barache, C., Barbato, D., Barros, M., Barstow, M. A., Bartolomé, S., Bassilana, J. -L., Bauchet, N., Baudesson-Stella, A., Becciani, U., Bellazzini, M., Bernet, M., Bertone, S., Bianchi, L., Blanco-Cuaresma, S., Boch, T., Bombrun, A., Bossini, D., Bouquillon, S., Bragaglia, A., Bramante, L., Breedt, E., Bressan, A., Brouillet, N., Bucciarelli, B., Burlacu, A., Busonero, D., Butkevich, A. G., Buzzi, R., Caffau, E., Cancelliere, R., Cánovas, H., Cantat-Gaudin, T., Carballo, R., Carlucci, T., Carnerero, M. I, Carrasco, J. M., Casamiquela, L., Castellani, M., Castro-Ginard, A., Sampol, P. Castro, Chaoul, L., Charlot, P., Chemin, L., Chiavassa, A., Cioni, M. -R. L., Comoretto, G., Cooper, W. J., Cornez, T., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Dafonte, C., Dapergolas, A., David, M., David, P., de Laverny, P., De Luise, F., De March, R., De Ridder, J., de Souza, R., de Teodoro, P., de Torres, A., del Peloso, E. F., del Pozo, E., Delbo, M., Delgado, A., Delgado, H. E., Delisle, J. -B., Di Matteo, P., Diakite, S., Diener, C., Distefano, E., Dolding, C., Eappachen, D., Edvardsson, B., Enke, H., Esquej, P., Fabre, C., Fabrizio, M., Faigler, S., Fedorets, G., Fernique, P., Fienga, A., Figueras, F., Fouron, C., Fragkoudi, F., Fraile, E., Franke, F., Gai, M., Garabato, D., Garcia-Gutierrez, A., García-Torres, M., Garofalo, A., Gavras, P., Gerlach, E., Geyer, R., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Gomel, R., Gomez, A., Gonzalez-Santamaria, I., González-Vidal, J. J., Granvik, M., Gutiérrez-Sánchez, R., Guy, L. P., Hauser, M., Haywood, M., Helmi, A., Hidalgo, S. L., Hilger, T., Hładczuk, N., Hobbs, D., Holland, G., Huckle, H. E., Jasniewicz, G., Jonker, P. G., Campillo, J. Juaristi, Julbe, F., Karbevska, L., Kervella, P., Khanna, S., Kochoska, A., Kontizas, M., Kordopatis, G., Korn, A. J., Kostrzewa-Rutkowska, Z., Kruszyńska, K., Lambert, S., Lanza, A. F., Lasne, Y., Campion, J. -F. Le, Fustec, Y. Le, Lebreton, Y., Lebzelter, T., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Liao, S., Licata, E., Lindstrøm, H. E. P., Lister, T. A., Livanou, E., Lobel, A., Pardo, P. Madrero, Managau, S., Mann, R. G., Marchant, J. M., Marconi, M., Santos, M. M. S. Marcos, Marinoni, S., Marocco, F., Marshall, D. J., Polo, L. Martin, Martín-Fleitas, J. M., Masip, A., Massari, D., Mastrobuono-Battisti, A., Mazeh, T., McMillan, P. J., Messina, S., Michalik, D., Millar, N. R., Mints, A., Molina, D., Molinaro, R., Molnár, L., Montegriffo, P., Mor, R., Morbidelli, R., Morel, T., Morris, D., Mulone, A. F., Munoz, D., Muraveva, T., Murphy, C. P., Musella, I., Noval, L., Ordénovic, C., Orrù, G., Osinde, J., Pagani, C., Pagano, I., Palaversa, L., Palicio, P. A., Panahi, A., Pawlak, M., Esteller, X. Peñalosa, a}, A. Penttil\"{, Piersimoni, A. M., Pineau, F. -X., Plachy, E., Plum, G., Poggio, E., Poretti, E., Poujoulet, E., Prša, A., Pulone, L., Racero, E., Ragaini, S., Rainer, M., Raiteri, C. M., Rambaux, N., Ramos, P., Ramos-Lerate, M., Fiorentin, P. Re, Regibo, S., Reylé, C., Ripepi, V., Riva, A., Rixon, G., Robichon, N., Robin, C., Roelens, M., Rohrbasser, L., Romero-Gómez, M., Rowell, N., Royer, F., Rybicki, K. A., Sadowski, G., Sellés, A. Sagristà, Sahlmann, J., Salgado, J., Salguero, E., Samaras, N., Gimenez, V. Sanchez, Sanna, N., Santoveña, R., Sarasso, M., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Ségransan, D., Semeux, D., Shahaf, S., Siddiqui, H. I., Siebert, A., Siltala, L., Slezak, E., Smart, R. L., Solano, E., Solitro, F., Souami, D., Souchay, J., Spagna, A., Spoto, F., Steele, I. A., u}ller, H. Steidelm\"{, Stephenson, C. A., u}veges, M. S\"{, Szabados, L., Szegedi-Elek, E., Taris, F., Tauran, G., Taylor, M. B., Teixeira, R., Thuillot, W., Tonello, N., Torra, F., Torra, J., Turon, C., Unger, N., Vaillant, M., van Dillen, E., Vanel, O., Vecchiato, A., Viala, Y., Vicente, D., Voutsinas, S., Weiler, M., Wevers, T., Wyrzykowski, Ł., Yoldas, A., Yvard, P., Zhao, H., Zorec, J., Zucker, S., Zurbach, C., and Zwitter, T.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present the early installment of the third Gaia data release, Gaia EDR3, consisting of astrometry and photometry for 1.8 billion sources brighter than magnitude 21, complemented with the list of radial velocities from Gaia DR2. Gaia EDR3 contains celestial positions and the apparent brightness in G for approximately 1.8 billion sources. For 1.5 billion of those sources, parallaxes, proper motions, and the (G_BP-G_RP) colour are also available. The passbands for G, G_BP, and G_RP are provided as part of the release. For ease of use, the 7 million radial velocities from Gaia DR2 are included in this release, after the removal of a small number of spurious values. New radial velocities will appear as part of Gaia DR3. Finally, Gaia EDR3 represents an updated materialisation of the celestial reference frame (CRF) in the optical, the Gaia-CRF3, which is based solely on extragalactic sources. The creation of the source list for Gaia EDR3 includes enhancements that make it more robust with respect to high proper motion stars, and the disturbing effects of spurious and partially resolved sources. The source list is largely the same as that for Gaia DR2, but it does feature new sources and there are some notable changes. The source list will not change for Gaia DR3. Gaia EDR3 represents a significant advance over Gaia DR2, with parallax precisions increased by 30 percent, proper motion precisions increased by a factor of 2, and the systematic errors in the astrometry suppressed by 30--40 percent for the parallaxes and by a factor ~2.5 for the proper motions. The photometry also features increased precision, but above all much better homogeneity across colour, magnitude, and celestial position. A single passband for G, G_BP, and G_RP is valid over the entire magnitude and colour range, with no systematics above the 1 percent level., Comment: Accepted for A&A Special Issue on Gaia EDR3, 21 pages, 2 figures. This version includes the updates in the erratum (https://doi.org/10.1051/0004-6361/202039657e)

Published
2020
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9. The ASAS-SN Catalog of Variable Stars IX: The Spectroscopic Properties of Galactic Variable Stars

Author

Jayasinghe, T., Kochanek, C. S., Stanek, K. Z., Shappee, B. J., Holoien, T. W. -S., Thompson, Todd A., Prieto, J. L., Dong, Subo, Pawlak, M., Pejcha, O., Pojmanski, G., Otero, S., Hurst, N., and Will, D.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

The All-Sky Automated Survey for Supernovae (ASAS-SN) provides long baseline (${\sim}4$ yrs) $V-$band light curves for sources brighter than V$\lesssim17$ mag across the whole sky. We produced V-band light curves for a total of ${\sim}61.5$ million sources and systematically searched these sources for variability. We identified ${\sim} 426,000$ variables, including ${\sim} 219,000$ new discoveries. Most (${\sim}74\%$) of our discoveries are in the Southern hemisphere. Here we use spectroscopic information from LAMOST, GALAH, RAVE, and APOGEE to study the physical and chemical properties of these variables. We find that metal-poor eclipsing binaries have orbital periods that are shorter than metal-rich systems at fixed temperature. We identified rotational variables on the main-sequence, red giant branch and the red clump. A substantial fraction (${\gtrsim}80\%$) of the rotating giants have large $v_{\rm rot}$ or large NUV excesses also indicative of fast rotation. The rotational variables have unusual abundances suggestive of analysis problems. Semi-regular variables tend to be lower metallicity ($\rm [Fe/H]{\sim}-0.5$) than most giant stars. We find that the APOGEE DR16 temperatures of oxygen-rich semi-regular variables are strongly correlated with the $W_{RP}-W_{JK}$ color index for $\rm T_{eff}\lesssim3800$ K. Using abundance measurements from APOGEE DR16, we find evidence for Mg and N enrichment in the semi-regular variables. We find that the Aluminum abundances of the semi-regular variables are strongly correlated with the pulsation period, where the variables with $\rm P\gtrsim 60$ days are significantly depleted in Al., Comment: 44 pages, 33 figures. Accepted for publication in MNRAS

Published
2020
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10. The ASAS-SN Catalog of Variable Stars VII: Contact Binaries are Different Above and Below the Kraft Break

Author

Jayasinghe, T., Stanek, K. Z., Kochanek, C. S., Shappee, B. J., Pinsonneault, M. H., Holoien, T. W. -S., Thompson, Todd A., Prieto, J. L., Pawlak, M., Pejcha, O., Pojmanski, G., Otero, S., Hurst, N., and Will, D.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

We characterize ${\sim} 71,200$ W UMa type (EW) contact binaries, including ${\sim} 12,600$ new discoveries, using ASAS-SN $V$-band all-sky light curves along with archival data from Gaia, 2MASS, AllWISE, LAMOST, GALAH, RAVE, and APOGEE. There is a clean break in the EW period-luminosity relation at $\rm \log (\rm P/d){\simeq}-0.30$, separating the longer period early-type EW binaries from the shorter period, late-type systems. The two populations are even more cleanly separated in the space of period and effective temperature, by $\rm T_{eff}=6710\,K-1760\,K\,\log(P/0.5\,d)$. Early-type and late-type EW binaries follow opposite trends in $\rm T_{eff}$ with orbital period. For longer periods, early-type EW binaries are cooler, while late-type systems are hotter. We derive period-luminosity relationships (PLRs) in the $W_{JK}$, $V$, Gaia DR2 $G$, $J$, $H$, $K_s$ and $W_1$ bands for the late-type and early-type EW binaries separated both by period and effective temperature, and by period alone. The dichotomy of contact binaries is almost certainly related to the Kraft break and the related changes in envelope structure, winds and angular momentum loss., Comment: Accepted by MNRAS

Published
2019
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11. The ASAS-SN Catalog of Variable Stars V: Variables in the Southern Hemisphere

Author

Jayasinghe, T., Stanek, K. Z., Kochanek, C. S., Shappee, B. J., Holoien, T. W. -S., Thompson, Todd A., Prieto, J. L., Dong, Subo, Pawlak, M., Pejcha, O., Shields, J. V., Pojmanski, G., Otero, S., Hurst, N., Britt, C. A., and Will, D.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

The All-Sky Automated Survey for Supernovae (ASAS-SN) provides long baseline (${\sim}4$ yrs) light curves for sources brighter than V$\lesssim17$ mag across the whole sky. As part of our effort to characterize the variability of all the stellar sources visible in ASAS-SN, we have produced ${\sim}30.1$ million V-band light curves for sources in the southern hemisphere using the APASS DR9 catalog as our input source list. We have systematically searched these sources for variability using a pipeline based on random forest classifiers. We have identified ${\sim} 220,000$ variables, including ${\sim} 88,300$ new discoveries. In particular, we have discovered ${\sim}48,000$ red pulsating variables, ${\sim}23,000$ eclipsing binaries, ${\sim}2,200$ $\delta$-Scuti variables and ${\sim}10,200$ rotational variables. The light curves and characteristics of the variables are all available through the ASAS-SN variable stars database (https://asas-sn.osu.edu/variables). The pre-computed ASAS-SN V-band light curves for all the ${\sim}30.1$ million sources are available through the ASAS-SN photometry database (https://asas-sn.osu.edu/photometry). This effort will be extended to provide ASAS-SN light curves for sources in the northern hemisphere and for V$\lesssim17$ mag sources across the whole sky that are not included in APASS DR9., Comment: 17 pages, 14 figures. Accepted by MNRAS

Published
2019
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12. An analysis of binary microlensing event OGLE-2015-BLG-0060

Author

Tsapras, Y., Cassan, A., Ranc, C., Bachelet, E., Street, R., Udalski, A., Hundertmark, M., Bozza, V., Beaulieu, J. P., Marquette, J. B., Euteneuer, E., team, The RoboNet, Bramich, D. M., Dominik, M., Jaimes, R. Figuera, Horne, K., Mao, S., Menzies, J., Schmidt, R., Snodgrass, C., Steele, I. A., Wambsganss, J., collaboration, The OGLE, Mróz, P., Szymański, M. K., Soszyński, I., Skowron, J., Pietrukowicz, P., Kozłowski, S., Poleski, R., Ulaczyk, K., Pawlak, M., collaboration, The MiNDSTEp, Jørgensen, U. G., Skottfelt, J., Popovas, A., Ciceri, S., Korhonen, H., Kuffmeier, M., Evans, D. F., Peixinho, N., Hinse, T. C., Burgdorf, M. J., Southworth, J., Tronsgaard, R., Kerins, E., Andersen, M. I., Rahvar, S., Wang, Y., Wertz, O., Rabus, M., Novati, S. Calchi, D'Ago, G., Scarpetta, G., Mancini, L., collaboration, The MOA, Abe, F., Asakura, Y., Bennett, D. P., Bhattacharya, A., Donachie, M., Evans, P., Fukui, A., Hirao, Y., Itow, Y., Kawasaki, K., Koshimoto, N., Li, M. C. A., Ling, C. H., Masuda, K., Matsubara, Y., Muraki, Y., Miyazaki, S., Nagakane, M., Ohnishi, K., Rattenbury, N., Saito, To., Sharan, A., Shibai, H., Sullivan, D. J., Sumi, T., Suzuki, D., Tristram, P. J., Yamada, T., and Yonehara, A.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We present the analysis of stellar binary microlensing event OGLE-2015-BLG-0060 based on observations obtained from 13 different telescopes. Intensive coverage of the anomalous parts of the light curve was achieved by automated follow-up observations from the robotic telescopes of the Las Cumbres Observatory. We show that, for the first time, all main features of an anomalous microlensing event are well covered by follow-up data, allowing us to estimate the physical parameters of the lens. The strong detection of second-order effects in the event light curve necessitates the inclusion of longer-baseline survey data in order to constrain the parallax vector. We find that the event was most likely caused by a stellar binary-lens with masses $M_{\star1} = 0.87 \pm 0.12 M_{\odot}$ and $M_{\star2} = 0.77 \pm 0.11 M_{\odot}$. The distance to the lensing system is 6.41 $\pm 0.14$ kpc and the projected separation between the two components is 13.85 $\pm 0.16$ AU. Alternative interpretations are also considered., Comment: 13 pages, 5 figures, Published in MNRAS

Published
2019
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13. Full orbital solution for the binary system in the northern Galactic disc microlensing event Gaia16aye

Author

Wyrzykowski, Łukasz, Mróz, P., Rybicki, K. A., Gromadzki, M., Kołaczkowski, Z., Zieliński, M., Zieliński, P., Britavskiy, N., Gomboc, A., Sokolovsky, K., Hodgkin, S. T., Abe, L., Aldi, G. F., AlMannaei, A., Altavilla, G., Qasim, A. Al, Anupama, G. C., Awiphan, S., Bachelet, E., Bakıs, V., Baker, S., Bartlett, S., Bendjoya, P., Benson, K., Bikmaev, I. F., Birenbaum, G., Blagorodnova, N., Blanco-Cuaresma, S., Boeva, S., Bonanos, A. Z., Bozza, V., Bramich, D. M., Bruni, I., Burenin, R. A., Burgaz, U., Butterley, T., Caines, H. E., Caton, D. B., Novati, S. Calchi, Carrasco, J. M., Cassan, A., Cepas, V., Cropper, M., Chruślińska, M., Clementini, G., Clerici, A., Conti, D., Conti, M., Cross, S., Cusano, F., Damljanovic, G., Dapergolas, A., D'Ago, G., de Bruijne, J. H. J., Dennefeld, M., Dhillon, V. S., Dominik, M., Dziedzic, J., Ereceantalya, O., Eselevich, M. V., Esenoglu, H., Eyer, L., Jaimes, R. Figuera, Fossey, S. J., Galeev, A. I., Grebenev, S. A., Gupta, A. C., Gutaev, A. G., Hallakoun, N., Hamanowicz, A., Han, C., Handzlik, B., Haislip, J. B., Hanlon, L., Hardy, L. K., Harrison, D. L., van Heerden, H. J., Hoette, V. L., Horne, K., Hudec, R., Hundertmark, M., Ihanec, N., Irtuganov, E. N., Itoh, R., Iwanek, P., Jovanovic, M. D., Janulis, R., Jelínek, M., Jensen, E., Kaczmarek, Z., Katz, D., Khamitov, I. M., Kilic, Y., Klencki, J., Kolb, U., Kopacki, G., Kouprianov, V. V., Kruszyńska, K., Kurowski, S., Latev, G., Lee, C-H., Leonini, S., Leto, G., Lewis, F., Li, Z., Liakos, A., Littlefair, S. P., Lu, J., Manser, C. J., Mao, S., Maoz, D., Martin-Carrillo, A., Marais, J. P., Maskoliūnas, M., Maund, J. R., Meintjes, P. J., Melnikov, S. S., Ment, K., Mikołajczyk, P., Morrell, M., Mowlavi, N., Moździerski, D., Murphy, D., Nazarov, S., Netzel, H., Nesci, R., Ngeow, C. -C., Norton, A. J., Ofek, E. O., Pakstienė, E., Palaversa, L., Pandey, A., Paraskeva, E., Pawlak, M., Penny, M. T., Penprase, B. E., Piascik, A., Prieto, J. L., Qvam, J. K. T., Ranc, C., Rebassa-Mansergas, A., Reichart, D. E., Reig, P., Rhodes, L., Rivet, J. -P., Rixon, G., Roberts, D., Rosi, P., Russell, D. M., Sanchez, R. Zanmar, Scarpetta, G., Seabroke, G., Shappee, B. J., Schmidt, R., Shvartzvald, Y., Sitek, M., Skowron, J., Śniegowska, M., Snodgrass, C., Soares, P. S., van Soelen, B., Spetsieri, Z. T., Stankeviciūtė, A., Steele, I. A., Street, R. A., Strobl, J., Strubble, E., Szegedi, H., Ramirez, L. M. Tinjaca, Tomasella, L., Tsapras, Y., Vernet, D., Villanueva Jr., S., Vince, O., Wambsganss, J., van der Westhuizen, I. P., Wiersema, K., Wium, D., Wilson, R. W., Yoldas, A., Zhuchkov, R. Ya., Zhukov, D. G., Zdanavicius, J., Zoła, S., and Zubareva, A.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Gaia16aye was a binary microlensing event discovered in the direction towards the northern Galactic disc and was one of the first microlensing events detected and alerted to by the Gaia space mission. Its light curve exhibited five distinct brightening episodes, reaching up to I=12 mag, and it was covered in great detail with almost 25,000 data points gathered by a network of telescopes. We present the photometric and spectroscopic follow-up covering 500 days of the event evolution. We employed a full Keplerian binary orbit microlensing model combined with the motion of Earth and Gaia around the Sun to reproduce the complex light curve. The photometric data allowed us to solve the microlensing event entirely and to derive the complete and unique set of orbital parameters of the binary lensing system. We also report on the detection of the first-ever microlensing space-parallax between the Earth and Gaia located at L2. The properties of the binary system were derived from microlensing parameters, and we found that the system is composed of two main-sequence stars with masses 0.57$\pm$0.05 $M_\odot$ and 0.36$\pm$0.03 $M_\odot$ at 780 pc, with an orbital period of 2.88 years and an eccentricity of 0.30. We also predict the astrometric microlensing signal for this binary lens as it will be seen by Gaia as well as the radial velocity curve for the binary system. Events such as Gaia16aye indicate the potential for the microlensing method of probing the mass function of dark objects, including black holes, in directions other than that of the Galactic bulge. This case also emphasises the importance of long-term time-domain coordinated observations that can be made with a network of heterogeneous telescopes., Comment: accepted for publication in A&A, 24 pages, 10 figures, tables with the data will be available electronically

Published
2019
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14. Discovery and Follow-up of the Unusual Nuclear Transient OGLE17aaj

Author

Gromadzki, M., Hamanowicz, A., Wyrzykowski, L., Sokolovsky, K. V., Fraser, M., Kozlowski, Sz., Guillochon, J., Arcavi, I., Trakhtenbrot, B., Jonker, P. G., Mattila, S., Udalski, A., Szymanski, M. K., Soszynski, I., Poleski, R., Pietrukowicz, P., Skowron, J., Mroz, P., Ulaczyk, K., Pawlak, M., Rybicki, K. A., Sollerman, J., Taddia, F., Kostrzewa-Rutkowska, Z., Onori, F., Young, D. R., Maguire, K., Smartt, S. J., Inserra, C., Gal-Yam, A., Rau, A., Chen, T. -W., Angus, C. R., and Buckley, D. A. H.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on the discovery and follow-up of a peculiar transient, OGLE17aaj, which occurred in the nucleus of a weakly active galaxy. We investigate whether it can be interpreted as a new candidate for a tidal disruption event (TDE). We present the OGLE-IV light curve that covers the slow 60-day-long rise to maximum along with photometric, spectroscopic, and X-ray follow-up during the first year. OGLE17aaj is a nuclear transient exhibiting some properties similar to previously found TDEs, including a long rise time, lack of colour-temperature evolution, and high black-body temperature. On the other hand, its narrow emission lines and slow post-peak evolution are different from previously observed TDEs. Its spectrum and light-curve evolution is similar to F01004-2237 and AT 2017bgt. Signatures of historical low-level nuclear variability suggest that OGLE17aaj may instead be related to a new type of accretion event in active super-massive black holes., Comment: 5 pages, 3 figures, accepted for publication in Astronomy & Astrophysics as Letter to Editor

Published
2019
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15. The ASAS-SN Catalog of Variable Stars III: Variables in the Southern TESS Continuous Viewing Zone

Author

Jayasinghe, T., Stanek, K. Z., Kochanek, C. S., Shappee, B. J., Holoien, T. W. -S., Thompson, Todd A., Prieto, J. L., Dong, Subo, Pawlak, M., Pejcha, O., Shields, J. V., Pojmanski, G., Otero, S., Hurst, N., Britt, C. A., and Will, D.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

The All-Sky Automated Survey for Supernovae (ASAS-SN) provides long baseline (${\sim}4$ yrs) light curves for sources brighter than V$\lesssim17$ mag across the whole sky. The Transiting Exoplanet Survey Satellite (TESS) has started to produce high-quality light curves with a baseline of at least 27 days, eventually for most of the sky. The combination of ASAS-SN and TESS light curves probes both long and short term variability in great detail, especially towards the TESS continuous viewing zones (CVZ) at the ecliptic poles. We have produced ${\sim}1.3$ million V-band light curves covering a total of ${\sim}1000 \, \rm deg^2$ towards the southern TESS CVZ and have systematically searched these sources for variability. We have identified ${\sim} 11,700$ variables, including ${\sim} 7,000$ new discoveries. The light curves and characteristics of the variables are all available through the ASAS-SN variable stars database (https://asas-sn.osu.edu/variables). We also introduce an online resource to obtain pre-computed ASAS-SN V-band light curves (https://asas-sn.osu.edu/photometry) starting with the light curves of the ${\sim}1.3$ million sources studied in this work. This effort will be extended to provide ASAS-SN light curves for ${\sim}50\;$million sources over the entire sky., Comment: 13 pages, 12 figures. Accepted by MNRAS

Published
2018
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16. First assessment of the binary lens OGLE-2015_BLG-0232

Author

Bachelet, E., Bozza, V., Han, C., Udalski, A., Bond, I. A., Beaulieu, J. -P., Street, R. A., Kim, J. -I, Bramich, D. M., Cassan, A., Dominik, M., Jaimes, R. Figuera, Horne, K., Hundertmark, M., Mao, S., Menzies, J., Ranc, C., Schmidt, R., Snodgrass, C., Steele, I. A., Tsapras, Y., Wambsganss, J., Mróz, P., Soszyński, I., Szymański, M. K., Skowron, J., Pietrukowicz, P., Kozłowski, S., Poleski, R., Ulaczyk, K., Pawlak, M., Abe, F., Barry, R., Bennett, D. P., Bhattacharya, A., Donachie, M., Fukui, A., Hirao, Y., Itow, Y., Kawasaki, K., Kondo, I., Koshimoto, N., Li, M. Cheung Alex, Matsubara, Y., Muraki, Y., Miyazaki, S., Nagakane, M., Rattenbury, N. J., Suematsu, H., Sullivan, D. J., Sumi, T., Suzuki, D., Tristram, P. J., and Yonehara, A.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We present an analysis of the microlensing event OGLE-2015-BLG-0232. This event is challenging to characterize for two reasons. First, the light curve is not well sampled during the caustic crossing due to the proximity of the full Moon impacting the photometry quality. Moreover, the source brightness is difficult to estimate because this event is blended with a nearby K dwarf star. We found that the light curve deviations are likely due to a close brown dwarf companion (i.e., s = 0.55 and q = 0.06), but the exact nature of the lens is still unknown. We finally discuss the potential of follow-up observations to estimate the lens mass and distance in the future., Comment: Accepted in ApJ

Published
2018
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18. OGLE-2017-BLG-0039: Microlensing Event with Light from the Lens Identified from Mass Measurement

Author

Han, C., Jung, Y. K., Udalski, A., Bond, I., Bozza, V., Albrow, M. D., Chung, S. -J., Gould, A., Hwang, K. -H., Kim, D., Lee, C. -U., Kim, H. -W., Ryu, Y. -H., Shin, I. -G., Yee, J. C., Shvartzvald, Y., Cha, S. -M., Kim, S. -L., Kim, D. -J., Lee, D. -J., Lee, Y., Park, B. -G., Pogge, R. W., Szymański, M. K., Mróz, P., Skowron, J., Poleski, R., Soszyński, I., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., Pawlak, M., Abe, F., Barry, R., Bennett, D. P., Bhattacharya, A., Donachie, M., Evans, P., Fukui, A., Hirao, Y., Itow, Y., Kawasaki, K., Koshimoto, N., Li, M. C. A., Ling, C. H., Matsubara, Y., Miyazaki, S., Munakata, H., Muraki, Y., Nagakane, M., Ohnishi, K., Ranc, C., Rattenbury, N., Saito, T., Sharan, A., Sullivan, D. J., Sumi, T., Suzuki, D., Tristram, P. J., Yamada, T., and Yonehara, A.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present the analysis of the caustic-crossing binary microlensing event OGLE-2017-BLG-0039. Thanks to the very long duration of the event, with an event time scale $t_{\rm E}\sim 130$ days, the microlens parallax is precisely measured despite its small value of $\pie\sim 0.06$. The analysis of the well-resolved caustic crossings during both the source star's entrance and exit of the caustic yields the angular Einstein radius $\thetae\sim 0.6$~mas. The measured $\pie$ and $\thetae$ indicate that the lens is a binary composed of two stars with masses $\sim 1.0~M_\odot$ and $\sim 0.15~M_\odot$, and it is located at a distance of $\sim 6$ kpc. From the color and brightness of the lens estimated from the determined lens mass and distance, it is expected that $\sim 2/3$ of the $I$-band blended flux comes from the lens. Therefore, the event is a rare case of a bright lens event for which high-resolution follow-up observations can confirm the nature of the lens., Comment: 8 pages, 6 figures, 5 tables

Published
2018
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19. ASAS-SN Identification of FY Sct as a detached eclipsing binary system with a ~2.6 year period

Author

Jayasinghe, T., Stanek, K. Z., Kochanek, C. S., Shappee, B. J., Holoien, T. W. -S., Thompson, T. A., Prieto, J. L., Dong, Subo, Pawlak, M., and Pejcha, O.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We report the identification of the bright (V${\sim}13.3$ mag) star FY Sct as a long period detached eclipsing binary using a combined ASAS-SN and ASAS light curve spanning 2000-2018. The orbital period is P${\sim}2.57$ years and the primary eclipse lasts ${\sim}73$ days. The eclipse profile is suggestive of a disk eclipsing binary rather than a stellar component. We also detect ${\sim}0.4$ mag pulsations with a period of P${\sim78}$ d. The next eclipse begins on September, 28, 2018. Further photometric and spectroscopic observations are encouraged, particularly when the system is in eclipse., Comment: 3 pages, 1 figure. Accepted to RNAAS

Published
2018

20. The ASAS-SN Catalog of Variable Stars II: Uniform Classification of 412,000 Known Variables

Author

Jayasinghe, T., Stanek, K. Z., Kochanek, C. S., Shappee, B. J., Holoien, T. W. -S., Thompson, Todd A., Prieto, J. L., Dong, Subo, Pawlak, M., Pejcha, O., Shields, J. V., Pojmanski, G., Otero, S., Britt, C. A., and Will, D.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

The variable stars in the VSX catalog are derived from a multitude of inhomogeneous data sources and classification tools. This inhomogeneity complicates our understanding of variable star types, statistics, and properties, and it directly affects attempts to build training sets for current (and next) generation all-sky, time-domain surveys. We homogeneously analyze the ASAS-SN V-band light curves of ${\sim}412,000$ variables from the VSX catalog. The variables are classified using an updated random forest classifier with an $F_1$ score of 99.4\% and refinement criteria for individual classifications. We have derived periods for ${\sim}52,000$ variables in the VSX catalog that lack a period, and have reclassified ${\sim} 17,000$ sources into new broad variability groups with high confidence. We have also reclassified ${\sim} 94,000$ known variables with miscellaneous/generic classifications. The light curves, classifications, and a range of properties of the variables are all available through the ASAS-SN variable stars database (https://asas-sn.osu.edu/variables). We also include the V-band light curves for a set of ${\sim}4,000$ rare variables and transient sources, including cataclysmic variables, symbiotic binaries and flare stars., Comment: 37 pages, 42 figures, 11 tables. Accepted by MNRAS. The catalog of variable stars and the V-band light curves are available from the ASAS-SN Variable Stars Database at https://asas-sn.osu.edu/variables

Published
2018
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21. OGLE-2017-BLG-0537: Microlensing Event with a Resolvable Lens in $\lesssim 5$ years from High-resolution Follow-up Observations

Author

Jung, Y. K., Han, C., Udalski, A., Gould, A., Albrow, M. D., Chung, S. -J., Hwang, K. -H., Lee, C. -U., Ryu, Y. -H., Shin, I. -G., Shvartzvald, Y., Yee, J. C., Zang, W., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, D. -J., Lee, Y., Park, B. -G., Pogge, R. W., Kim, W. -T., Mróz, P., Poleski, R., Skowron, J., Szymański, M. K., Soszyński, I., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., and Pawlak, M.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present the analysis of the binary-lens microlensing event OGLE-2017-BLG-0537. The light curve of the event exhibits two strong caustic-crossing spikes among which the second caustic crossing was resolved by high-cadence surveys. It is found that the lens components with a mass ratio $\sim 0.5$ are separated in projection by $\sim 1.3\thetae$, where $\thetae$ is the angular Einstein radius. Analysis of the caustic-crossing part yields $\thetae=1.77\pm 0.16$~mas and a lens-source relative proper motion of $\mu =12.4\pm 1.1~{\rm mas}~{\rm yr}^{-1}$. The measured $\mu$ is the third highest value among the events with measured proper motions and $\sim 3$ times higher than the value of typical Galactic bulge events, making the event a strong candidate for follow-up observations to directly image the lens by separating it from the source. From the angular Einstein radius combined with the microlens parallax, it is estimated that the lens is composed of two main-sequence stars with masses $M_1\sim 0.4~M_\odot$ and $M_2\sim 0.2~M_\odot$ located at a distance of $D_{\rm L}\sim 1.2$~kpc. However, the physical lens parameters are not very secure due to the weak microlens-parallax signal, and thus we cross check the parameters by conducting a Bayesian analysis based on the measured Einstein radius and event timescale combined with the blending constraint. From this, we find that the physical parameters estimated from the Bayesian analysis are consistent with those based on the measured microlens parallax. Resolving the lens from the source can be done in about 5 years from high-resolution follow-up observations and this will provide a rare opportunity to test and refine the microlensing model., Comment: 9 pages, 6 figure, 2 tables

Published
2018
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22. Gaia Data Release 2: Observational Hertzsprung-Russell diagrams

Author

Gaia Collaboration, Babusiaux, C., van Leeuwen, F., Barstow, M. A., Jordi, C., Vallenari, A., Bossini, D., Bressan, A., Cantat-Gaudin, T., van Leeuwen, M., Brown, A. G. A., Prusti, T., de Bruijne, J. H. J., Bailer-Jones, C. A. L., Biermann, M., Evans, D. W., Eyer, L., Jansen, F., Klioner, S. A., Lammers, U., Lindegren, L., Luri, X., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Siddiqui, H. I., Soubiran, C., Walton, N. A., Arenou, F., Bastian, U., Cropper, M., Drimmel, R., Katz, D., Lattanzi, M. G., Bakker, J., Cacciari, C., Castañeda, J., Chaoul, L., Cheek, N., DeAngeli, F., Fabricius, C., Guerra, R., Holl, B., Masana, E., Messineo, R., Mowlavi, N., Nienartowicz, K., Panuzzo, P., Portell, J., Riello, M., Seabroke, G. M., Tanga, P., Thévenin, F., Gracia-Abril, G., Comoretto, G., Garcia-Reinaldos, M., Teyssier, D., Altmann, M., Andrae, R., Audard, M., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Burgess, P., Busso, G., Carry, B., Cellino, A., Clementini, G., Clotet, M., Creevey, O., Davidson, M., DeRidder, J., Delchambre, L., Dell'Oro, A., Ducourant, C., Fernández-Hernández, J., Fouesneau, M., Frémat, Y., Galluccio, L., García-Torres, M., González-Núñez, J., González-Vidal, J. J., Gosset, E., Guy, L. P., Halbwachs, J. -L., Hambly, N. C., Harrison, D. L., Hernández, J., Hestroffer, D., Hodgkin, S. T., Hutton, A., Jasniewicz, G., Jean-Antoine-Piccolo, A., Jordan, S., Korn, A. J., Krone-Martins, A., Lanzafame, A. C., Lebzelter, T., Löffler, W., Manteiga, M., Marrese, P. M., Martín-Fleitas, J. M., Moitinho, A., Mora, A., Muinonen, K., Osinde, J., Pancino, E., Pauwels, T., Petit, J. -M., Recio-Blanco, A., Richards, P. J., Rimoldini, L., Robin, A. C., Sarro, L. M., Siopis, C., Smith, M., Sozzetti, A., Süveges, M., Torra, J., vanReeven, W., Abbas, U., Aramburu, A. Abreu, Accart, S., Aerts, C., Altavilla, G., Álvarez, M. A., Alvarez, R., Alves, J., Anderson, R. I., Andrei, A. H., Varela, E. Anglada, Antiche, E., Antoja, T., Arcay, B., Astraatmadja, T. L., Bach, N., Baker, S. G., Balaguer-Núñez, L., Balm, P., Barache, C., Barata, C., Barbato, D., Barblan, F., Barklem, P. S., Barrado, D., Barros, M., Muñoz, S. Bartholomé, Bassilana, J. -L., Becciani, U., Bellazzini, M., Berihuete, A., Bertone, S., Bianchi, L., Bienaymé, O., Blanco-Cuaresma, S., Boch, T., Boeche, C., Bombrun, A., Borrachero, R., Bouquillon, S., Bourda, G., Bragaglia, A., Bramante, L., Breddels, M. A., Brouillet, N., Brüsemeister, T., Brugaletta, E., Bucciarelli, B., Burlacu, A., Busonero, D., Butkevich, A. G., Buzzi, R., Caffau, E., Cancelliere, R., Cannizzaro, G., Carballo, R., Carlucci, T., Carrasco, J. M., Casamiquela, L., Castellani, M., Castro-Ginard, A., Charlot, P., Chemin, L., Chiavassa, A., Cocozza, G., Costigan, G., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Cuypers, J., Dafonte, C., Damerdji, Y., Dapergolas, A., David, P., David, M., deLaverny, P., DeLuise, F., DeMarch, R., deMartino, D., deSouza, R., deTorres, A., Debosscher, J., delPozo, E., Delbo, M., Delgado, A., Delgado, H. E., Diakite, S., Diener, C., Distefano, E., Dolding, C., Drazinos, P., Durán, J., Edvardsson, B., Enke, H., Eriksson, K., Esquej, P., Bontemps, G. Eynard, Fabre, C., Fabrizio, M., Faigler, S., Falcão, A. J., Casas, M. Farràs, Federici, L., Fedorets, G., Fernique, P., Figueras, F., Filippi, F., Findeisen, K., Fonti, A., Fraile, E., Fraser, M., Frézouls, B., Gai, M., Galleti, S., Garabato, D., García-Sedano, F., Garofalo, A., Garralda, N., Gavel, A., Gavras, P., Gerssen, J., Geyer, R., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Glass, F., Gomes, M., Granvik, M., Gueguen, A., Guerrier, A., Guiraud, J., Gutiérrez-Sánchez, R., Haigron, R., Hatzidimitriou, D., Hauser, M., Haywood, M., Heiter, U., Helmi, A., Heu, J., Hilger, T., Hobbs, D., Hofmann, W., Holland, G., Huckle, H. E., Hypki, A., Icardi, V., Janßen, K., JevardatdeFombelle, G., Jonker, P. G., Juhász, Á. L., Julbe, F., Karampelas, A., Kewley, A., Klar, J., Kochoska, A., Kohley, R., Kolenberg, K., Kontizas, M., Kontizas, E., Koposov, S. E., Kordopatis, G., Kostrzewa-Rutkowska, Z., Koubsky, P., Lambert, S., Lanza, A. F., Lasne, Y., Lavigne, J. -B., LeFustec, Y., LePoncin-Lafitte, C., Lebreton, Y., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Lenhardt, H., Leroux, F., Liao, S., Licata, E., Lindstrøm, H. E. P., Lister, T. A., Livanou, E., Lobel, A., López, M., Managau, S., Mann, R. G., Mantelet, G., Marchal, O., Marchant, J. M., Marconi, M., Marinoni, S., Marschalkó, G., Marshall, D. J., Martino, M., Marton, G., Mary, N., Massari, D., Matijevič, G., Mazeh, T., McMillan, P. J., Messina, S., Michalik, D., Millar, N. R., Molina, D., Molinaro, R., Molnár, L., Montegriffo, P., Mor, R., Morbidelli, R., Morel, T., Morris, D., Mulone, A. F., Muraveva, T., Musella, I., Nelemans, G., Nicastro, L., Noval, L., O'Mullane, W., Ordénovic, C., Ordóñez-Blanco, D., Osborne, P., Pagani, C., Pagano, I., Pailler, F., Palacin, H., Palaversa, L., Panahi, A., Pawlak, M., Piersimoni, A. M., Pineau, F. -X., Plachy, E., Plum, G., Poggio, E., Poujoulet, E., Prša, A., Pulone, L., Racero, E., Ragaini, S., Rambaux, N., Ramos-Lerate, M., Regibo, S., Reylé, C., Riclet, F., Ripepi, V., Riva, A., Rivard, A., Rixon, G., Roegiers, T., Roelens, M., Romero-Gómez, M., Rowell, N., Royer, F., Ruiz-Dern, L., Sadowski, G., Sellés, T. Sagristà, Sahlmann, J., Salgado, J., Salguero, E., Sanna, N., Santana-Ros, T., Sarasso, M., Savietto, H., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Ségransan, D., Shih, I-C., Siltala, L., Silva, A. F., Smart, R. L., Smith, K. W., Solano, E., Solitro, F., Sordo, R., SoriaNieto, S., Souchay, J., Spagna, A., Spoto, F., Stampa, U., Steele, I. A., Steidelmüller, H., Stephenson, C. A., Stoev, H., Suess, F. F., Surdej, J., Szabados, L., Szegedi-Elek, E., Tapiador, D., Taris, F., Tauran, G., Taylor, M. B., Teixeira, R., Terrett, D., Teyssandier, P., Thuillot, W., Titarenko, A., TorraClotet, F., Turon, C., Ulla, A., Utrilla, E., Uzzi, S., Vaillant, M., Valentini, G., Valette, V., vanElteren, A., Van Hemelryck, E., Vaschetto, M., Vecchiato, A., Veljanoski, J., Viala, Y., Vicente, D., Vogt, S., vonEssen, C., Voss, H., Votruba, V., Voutsinas, S., Walmsley, G., Weiler, M., Wertz, O., Wevers, T., Wyrzykowski, Ł., Yoldas, A., Žerjal, M., Ziaeepour, H., Zorec, J., Zschocke, S., Zucker, S., Zurbach, C., and Zwitter, T.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

We highlight the power of the Gaia DR2 in studying many fine structures of the Hertzsprung-Russell diagram (HRD). Gaia allows us to present many different HRDs, depending in particular on stellar population selections. We do not aim here for completeness in terms of types of stars or stellar evolutionary aspects. Instead, we have chosen several illustrative examples. We describe some of the selections that can be made in Gaia DR2 to highlight the main structures of the Gaia HRDs. We select both field and cluster (open and globular) stars, compare the observations with previous classifications and with stellar evolutionary tracks, and we present variations of the Gaia HRD with age, metallicity, and kinematics. Late stages of stellar evolution such as hot subdwarfs, post-AGB stars, planetary nebulae, and white dwarfs are also analysed, as well as low-mass brown dwarf objects. The Gaia HRDs are unprecedented in both precision and coverage of the various Milky Way stellar populations and stellar evolutionary phases. Many fine structures of the HRDs are presented. The clear split of the white dwarf sequence into hydrogen and helium white dwarfs is presented for the first time in an HRD. The relation between kinematics and the HRD is nicely illustrated. Two different populations in a classical kinematic selection of the halo are unambiguously identified in the HRD. Membership and mean parameters for a selected list of open clusters are provided. They allow drawing very detailed cluster sequences, highlighting fine structures, and providing extremely precise empirical isochrones that will lead to more insight in stellar physics. Gaia DR2 demonstrates the potential of combining precise astrometry and photometry for large samples for studies in stellar evolution and stellar population and opens an entire new area for HRD-based studies., Comment: Published in the A&A Gaia Data Release 2 special issue. Tables 2 and A.4 corrected. Tables available at http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/616/A10

Published
2018
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23. Gaia Data Release 2: Summary of the variability processing & analysis results

Author

Holl, B., Audard, M., Nienartowicz, K., de Fombelle, G. Jevardat, Marchal, O., Mowlavi, N., Clementini, G., De Ridder, J., Evans, D. W., Guy, L. P., Lanzafame, A. C., Lebzelter, T., Rimoldini, L., Roelens, M., Zucker, S., Distefano, E., Garofalo, A., Lecoeur-Taïbi, I., Lopez, M., Molinaro, R., Muraveva, T., Panahi, A., Regibo, S., Ripepi, V., Sarro, L. M., Aerts, C., Anderson, R. I., Charnas, J., Barblan, F., Blanco-Cuaresma, S., Busso, G., Cuypers, J., De Angeli, F., Glass, F., Grenon, M., Juhász, Á. L., Kochoska, A., Koubsky, P., Lanza, A. F., Leccia, S., Lorenz, D., Marconi, M., Marschalk, G., Mazeh, T., Messina, S., Mignard, F., Moitinho, A., Molnár, L., Morgenthaler, S., Musella, I., Ordenovic, C., Ordóñez, D., Pagano, I., Palaversa, L., Pawlak, M., Plachy, E., Prša, A., Riello, M., Süveges, M., Szabados, L., Szegedi-Elek, E., Votruba, V., and Eyer, L.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The Gaia Data Release 2 (DR2): we summarise the processing and results of the identification of variable source candidates of RR Lyrae stars, Cepheids, long period variables (LPVs), rotation modulation (BY Dra-type) stars, delta Scuti & SX Phoenicis stars, and short-timescale variables. In this release we aim to provide useful but not necessarily complete samples of candidates. The processed Gaia data consist of the G, BP, and RP photometry during the first 22 months of operations as well as positions and parallaxes. Various methods from classical statistics, data mining and time series analysis were applied and tailored to the specific properties of Gaia data, as well as various visualisation tools. The DR2 variability release contains: 228'904 RR Lyrae stars, 11'438 Cepheids, 151'761 LPVs, 147'535 stars with rotation modulation, 8'882 delta Scuti & SX Phoenicis stars, and 3'018 short-timescale variables. These results are distributed over a classification and various Specific Object Studies (SOS) tables in the Gaia archive, along with the three-band time series and associated statistics for the underlying 550'737 unique sources. We estimate that about half of them are newly identified variables. The variability type completeness varies strongly as function of sky position due to the non-uniform sky coverage and intermediate calibration level of this data. The probabilistic and automated nature of this work implies certain completeness and contamination rates which are quantified so that users can anticipate their effects. This means that even well-known variable sources can be missed or misidentified in the published data. The DR2 variability release only represents a small subset of the processed data. Future releases will include more variable sources and data products; however, DR2 shows the (already) very high quality of the data and great promise for variability studies., Comment: 21 pages, 10 figures, 5 tables, accepted by Astronomy & Astrophysics, added several language corrections, and expanded Gaia archive query examples

Published
2018
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24. MOA-2015-BLG-337: A Planetary System with a Low-mass Brown Dwarf/Planetary Boundary Host, or a Brown Dwarf Binary

Author

Miyazaki, S., Sumi, T., Bennett, D. P., Gould, A., Udalski, A., Bond, I. A., Koshimoto, N., Nagakane, M., Rattenbury, N., Abe, F., Bhattacharya, A., Barry, R., Donachie, M., Fukui, A., Hirao, Y., Itow, Y., Kawasaki, K., Li, M. C., Ling, C. H., Matsubara, Y., Matsuo, T., Muraki, Y., Ohnishi, K., Ranc, C., Saito, T., Sharan, A., Shibai, H., Suematsu, H., Suzuki, D., Sullivan, D. J., Tristram, P. J., Yamada, T., Yonehara, A., owski, S., Mr'oz, P., Pawlak, M., Poleski, R., Pietrukowicz, P., Skowron, J., Soszy'nski, I., Szyma'nski, M. K., Ulaczyk, K., Albrow, M. D., Chung, S. -J., Han, C., Jung, Y. K., Hwang, K. -H., Ryu, Y. -H., Shin, I. -G., Shvartzvald, Y., Yee, J. C., Zang, W., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., and Pogge, R. W.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery and the analysis of the short timescale binary-lens microlensing event, MOA-2015-BLG-337. The lens system could be a planetary system with a very low mass host, around the brown dwarf/planetary mass boundary, or a brown dwarf binary. We found two competing models that explain the observed light curves with companion/host mass ratios of q~0.01 and ~0.17, respectively. From the measurement of finite source effects in the best-fit planetary model, we find a relatively small angular Einstein radius of theta_E ~ 0.03 mas which favors a low mass lens. We conduct a Bayesian analysis to obtain the probability distribution of the lens properties. The results for the planetary models strongly depend on the minimum mass, M_min, in the assumed mass function. In summary, there are two solutions of the lens system: (1) a brown dwarf/planetary mass boundary object orbited by a super-Neptune (the planetary model with M_min=0.001 M_sun) and (2) a brown dwarf binary (the binary model). If the planetary models is correct, this system can be one of a new class of planetary system, having a low host mass and also a planetary mass ratio (q <0.03) between the host and its companion. The discovery of the event is important for the study of planetary formation in very low mass objects. In addition, it is important to consider all viable solutions in these kinds of ambiguous events in order for the future comprehensive statistical analyses of planetary/binary microlensing events., Comment: 17 pages, 7 figures, Accepted for publication in AJ

Published
2018
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25. OGLE-2017-BLG-0482Lb: A Microlensing Super-Earth Orbiting a Low-mass Host Star

Author

Han, C., Hirao, Y., Udalski, A., Lee, C. -U., Bozza, V., Gould, A., Abe, F., Barry, R., Bond, I. A., Bennett, D. P., Bhattacharya, A., Donachie, M., Evans, P., Fukui, A., Itow, Y., Kawasaki, K., Koshimoto, N., Li, M. C. A., Ling, C. H., Matsubara, Y., Miyazaki, S., Munakata, H., Muraki, Y., Nagakane, M., Ohnishi, K., Ranc, C., Rattenbury, N., Saito, T., Sharan, A., Sullivan, D. J., Sumi, T., Suzuki, D., Tristram, P. J., Yamada, T., Yonehara, A., Mróz, P., Poleski, R., Kozłowski, S., Soszyński, I., Pietrukowicz, P., Skowron, J., Szymańsk, M. K., Ulaczyk, K., Pawlak, M., Rybicki, K., Iwanek, P., Albrow, M. D., Chung, S. -J., Hwang, K. -H., Jung, Y. K., Kim, D., Kim, W. -T., Kim, H. -W., Ryu, Y. -H., Shin, I. -G., Shvartzvald, Y., Yee, J. C., Zhu, W., Cha, S. -M., Kim, S. -L., Kim, D. -J., Lee, D. -J., Lee, Y., Park, B. -G., and Pogge, R. W.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery of a planetary system in which a super-earth orbits a late M-dwarf host. The planetary system was found from the analysis of the microlensing event OGLE-2017-BLG-0482, wherein the planet signal appears as a short-term anomaly to the smooth lensing light curve produced by the host. Despite its weak signal and short duration, the planetary signal was firmly detected from the dense and continuous coverage by three microlensing surveys. We find a planet/host mass ratio of $q\sim 1.4\times 10^{-4}$. We measure the microlens parallax $\pi_{\rm E}$ from the long-term deviation in the observed lensing light curve, but the angular Einstein radius $\theta_{\rm E}$ cannot be measured because the source trajectory did not cross the planet-induced caustic. Using the measured event timescale and the microlens parallax, we find that the masses of the planet and the host are $M_{\rm p}=9.0_{-4.5}^{+9.0}\ M_\oplus$ and $M_{\rm host}=0.20_{-0.10}^{+0.20}\ M_\odot$, respectively, and the projected separation between them is $a_\perp=1.8_{-0.7}^{+0.6}$ au. The estimated distance to the lens is $D_{\rm L}=5.8_{-2.1}^{+1.8}$ kpc. The discovery of the planetary system demonstrates that microlensing provides an important method to detect low-mass planets orbiting low-mass stars., Comment: 10 pages, 10 figures, 2 tables

Published
2018
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26. OGLE-2017-BLG-1522: A giant planet around a brown dwarf located in the Galactic bulge

Author

Jung, Y. K., Udalski, A., Gould, A., Ryu, Y. -H., Yee, J. C., Han, C., Albrow, M. D., Lee, C. -U., Kim, S. -L., Hwang, K. -H., Chung, S. -J., Shin, I. -G., Zhu, W., Cha, S. -M., Kim, D. -J., Lee, Y., Park, B. -G., Lee, D. -J., Kim, H. -W., Pogge, R. W., Szymański, M. K., Mróz, P., Poleski, R., Skowron, J., Pietrukowicz, P., Soszyński, I., Kozłowski, S., Ulaczyk, K., Pawlak, M., and Rybicki, K.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

We report the discovery of a giant planet in the OGLE-2017-BLG-1522 microlensing event. The planetary perturbations were clearly identified by high-cadence survey experiments despite the relatively short event timescale of $t_{\rm E} \sim 7.5$ days. The Einstein radius is unusually small, $\theta_{\rm E} = 0.065\,$mas, implying that the lens system either has very low mass or lies much closer to the microlensed source than the Sun, or both. A Bayesian analysis yields component masses $(M_{\rm host}, M_{\rm planet})=(46_{-25}^{+79}, 0.75_{-0.40}^{+1.26})~M_{\rm J}$ and source-lens distance $D_{\rm LS} = 0.99_{-0.54}^{+0.91}~{\rm kpc}$, implying that this is a brown-dwarf/Jupiter system that probably lies in the Galactic bulge, a location that is also consistent with the relatively low lens-source relative proper motion $\mu = 3.2 \pm 0.5~{\rm mas}~{\rm yr^{-1}}$. The projected companion-host separation is $0.59_{-0.11}^{+0.12}~{\rm AU}$, indicating that the planet is placed beyond the snow line of the host, i.e., $a_{sl} \sim 0.12~{\rm AU}$. Planet formation scenarios combined with the small companion-host mass ratio $q \sim 0.016$ and separation suggest that the companion could be the first discovery of a giant planet that formed in a protoplanetary disk around a brown dwarf host., Comment: 20 pages, 6 figures

Published
2018
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27. Spitzer Opens New Path to Break Classic Degeneracy for Jupiter-Mass Microlensing Planet OGLE-2017-BLG-1140Lb

Author

Novati, S. Calchi, Skowron, J., Jung, Y. K., Beichman, C., Bryden, G., Carey, S., Gaudi, B. S., Henderson, C. B., Shvartzvald, Y., Yee, J. C., Zhu, W., Udalski, A., Szymański, M. K., Mróz, P., Poleski, R., Soszyński, I., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., Pawlak, M., Rybicki, K., Iwanek, P., Albrow, M. D., Chung, S. -J., Gould, A., Han, C., Hwang, K. -H., Ryu, Y. -H., Shin, I. -G., Zang, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., and Pogge, R. W.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

We analyze the combined Spitzer and ground-based data for OGLE-2017-BLG-1140 and show that the event was generated by a Jupiter-class $(m_p\simeq 1.6\,M_{\rm jup})$ planet orbiting a mid-late M dwarf $(M\simeq 0.2\,M_\odot)$ that lies $D_{LS}\simeq 1.0\,\mathrm{kpc}$ in the foreground of the microlensed, Galactic-bar, source star. The planet-host projected separation is $a_\perp \simeq 1.0\,\mathrm{au}$, i.e., well-beyond the snow line. By measuring the source proper motion ${\mathbf{\mu}}_s$ from ongoing, long-term OGLE imaging, and combining this with the lens-source relative proper motion ${\mathbf{\mu}}_\mathrm{rel}$ derived from the microlensing solution, we show that the lens proper motion ${\mathbf{\mu}}_l={\mathbf{\mu}}_\mathrm{rel} + {\mathbf{\mu}}_s$ is consistent with the lens lying in the Galactic disk, although a bulge lens is not ruled out. We show that while the Spitzer and ground-based data are comparably well fitted by planetary (i.e., binary-lens, 2L1S) models and by binary-source (1L2S) models, the combination of Spitzer and ground-based data decisively favor the planetary model. This is a new channel to resolve the 2L1S/1L2S degeneracy, which can be difficult to break in some cases., Comment: Revised version accepted for publication in The Astronomical Journal

Published
2018
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28. The ASAS-SN Catalog of Variable Stars I: The Serendipitous Survey

Author

Jayasinghe, T., Kochanek, C. S., Stanek, K. Z., Shappee, B. J., Holoien, T. W. -S., Thompson, Todd A., Prieto, J. L., Dong, Subo, Pawlak, M., Shields, J. V., Pojmanski, G., Otero, S., Britt, C. A., and Will, D.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

The All-Sky Automated Survey for Supernovae (ASAS-SN) is the first optical survey to routinely monitor the whole sky with a cadence of $\sim2-3$ days down to V$\lesssim17$ mag. ASAS-SN has monitored the whole sky since 2014, collecting $\sim100-500$ epochs of observations per field. The V-band light curves for candidate variables identified during the search for supernovae are classified using a random forest classifier and visually verified. We present a catalog of 66,179 bright, new variable stars discovered during our search for supernovae, including 27,479 periodic variables and 38,700 irregular variables. V-band light curves for the ASAS-SN variables are available through the ASAS-SN variable stars database (https://asas-sn.osu.edu/variables). The database will begin to include the light curves of known variable stars in the near future along with the results for a systematic, all-sky variability survey., Comment: 21 pages, 19 figures, 5 tables. Accepted for publication in MNRAS. The catalog of variable stars and the V-band light curves are available from the ASAS-SN Variable Stars Database at https://asas-sn.osu.edu/variables

Published
2018
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29. OGLE-2017-BLG-0373Lb: A Jovian Mass-Ratio Planet Exposes A New Accidental Microlensing Degeneracy

Author

Skowron, J., Ryu, Y. -H., Hwang, K. -H., Udalski, A., Mróz, P., Kozłowski, S., Soszyński, I., Pietrukowicz, P., Szymański, M. K., Poleski, R., Ulaczyk, K., Pawlak, M., Rybicki, K., Iwanek, P., Albrow, M. D., Chung, S. -J., Gould, A., Han, C., Jung, Y. K., Shin, I. -G., Shvartzvald, Y., Yee, J. C., Zang, W., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., and Pogge, R. W.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery of microlensing planet OGLE-2017-BLG-0373Lb. We show that while the planet-host system has an unambiguous microlens topology, there are two geometries within this topology that fit the data equally well, which leads to a factor 2.5 difference in planet-host mass ratio, i.e., $q=1.5\times 10^{-3}$ vs. $q=0.6\times 10^{-3}$. We show that this is an "accidental degeneracy" in the sense that it is due to a gap in the data. We dub it "the caustic-chirality degeneracy". We trace the mathematical origins of this degeneracy, which should enable similar degenerate solutions to be easily located in the future. A Bayesian estimate, based on a Galactic model, yields a host mass $M=0.25^{+0.30}_{-0.15} M_\odot$ at a distance $D_L=5.9^{+1.3}_{-1.95}$ kpc. The lens-source relative proper motion is relatively fast, $\mu=9$ mas/yr, which implies that the host mass and distance can be determined by high-resolution imaging after about 10 years. The same observations could in principle resolve the discrete degeneracy in $q$, but this will be more challenging., Comment: 24 pages, 7 figures, 3 tables. Accepted for publication in Acta Astronomica. Light curves and callibration data are available on arXiv as Ancillary files and http://www.astrouw.edu.pl/~jskowron/ogle/ob170373/

Published
2018
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30. OGLE-2017-BLG-0329L: A Microlensing Binary Characterized with Dramatically Enhanced Precision Using Data from Space-based Observations

Author

Han, C., Novati, S. Calchi, Udalski, A., Lee, C. -U., Gould, A., Bozza, V., Mróz, P., Pietrukowicz, P., Skowron, J., Szymański, M. K., Poleski, R., Soszyński, I., Kozłowski, S., Ulaczyk, K., Pawlak, M., Rybicki, K., Iwanek, P., Albrow, M. D., Chung, S. -J., Hwang, K. -H., Jung, Y. K., Ryu, Y. -H., Shin, I. -G., Shvartzvald, Y., Yee, J. C., Zang, W., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, D. -J., Lee, Y., Park, B. -G., Pogge, R. W., Kim, W. -T., Beichman, C., Bryden, G., Carey, S., Gaudi, B. S., Henderson, C. B., Dominik, M., Helling, C., Hundertmark, M., Jørgensen, U. G., Longa-Peña, P., Lowry, S., Sajadian, S., Burgdorf, M. J., Campbell-White, J., Ciceri, S., Evans, D. F., Haikala, L. K., Hinse, T. C., Rahvar, S., Rabus, M., and Snodgrass, C.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Mass measurements of gravitational microlenses require one to determine the microlens parallax $\pie$, but precise $\pie$ measurement, in many cases, is hampered due to the subtlety of the microlens-parallax signal combined with the difficulty of distinguishing the signal from those induced by other higher-order effects. In this work, we present the analysis of the binary-lens event OGLE-2017-BLG-0329, for which $\pie$ is measured with a dramatically improved precision using additional data from space-based $Spitzer$ observations. We find that while the parallax model based on the ground-based data cannot be distinguished from a zero-$\pie$ model at 2$\sigma$ level, the addition of the $Spitzer$ data enables us to identify 2 classes of solutions, each composed of a pair of solutions according to the well-known ecliptic degeneracy. It is found that the space-based data reduce the measurement uncertainties of the north and east components of the microlens-parallax vector $\pivec_{\rm E}$ by factors $\sim 18$ and $\sim 4$, respectively. With the measured microlens parallax combined with the angular Einstein radius measured from the resolved caustic crossings, we find that the lens is composed of a binary with components masses of either $(M_1,M_2)\sim (1.1,0.8)\ M_\odot$ or $\sim (0.4,0.3)\ M_\odot$ according to the two solution classes. The first solution is significantly favored but the second cannot be securely ruled out based on the microlensing data alone. However, the degeneracy can be resolved from adaptive optics observations taken $\sim 10$ years after the event., Comment: 9 pages, 4 tables, 6 figures

Published
2018
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31. OGLE-2016-BLG-1266: A Probable Brown-Dwarf/Planet Binary at the Deuterium Fusion Limit

Author

Albrow, M. D., Yee, J. C., Udalski, A., Novati, S. Calchi, Carey, S., Henderson, C. B., Beichman, C., Bryden, G., Gaudi, B. S., Shvartzvald, Y., Szymanśki, M. K., Mroź, P., Skowron, J., Poleski, R., Soszynśki, I., Kozlowski, S., Pietrukowicz, ., Ulaczyk, K., Pawlak, M., Chung, S. -J., Gould, A., Han, C., Hwang, K. -H., Jung, Y. K., Ryu, Y. -H., Shin, I. -G., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., and Pogge, R. W.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery, via the microlensing method, of a new very-low-mass binary system. By combining measurements from Earth and from the Spitzer telescope in Earth-trailing orbit, we are able to measure the microlensing parallax of the event, and find that the lens likely consists of an $(12.0 \pm 0.6) M_{\rm J}$ + $(15.7 \pm 1.5) M_{\rm J}$ super-Jupiter / brown-dwarf pair. The binary is located at a distance of $(3.08 \pm 0.18)$ kpc in the Galactic Plane, and the components have a projected separation of $(0.43 \pm 0.03)$ AU. Two alternative solutions with much lower likelihoods are also discussed, an 8- and 6-$M_{\rm J}$ model and a 90- and 70-$M_{\rm J}$ model. Although disfavored at the 3-$\sigma$ and 5-$\sigma$ levels, these alternatives cannot be rejected entirely. We show how the more-massive of these models could be tested with future direct imaging., Comment: 23 pages, 7 figures, submitted to AAS Journals

Published
2018
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32. OGLE-2017-BLG-1130: The First Binary Gravitational Microlens Detected From Spitzer Only

Author

Wang, Tianshu, Novati, S. Calchi, Udalski, A., Gould, A., Mao, Shude, Zang, W., Beichman, C., Bryden, G., Carey, S., Gaudi, B. S., Henderson, C. B., Shvartzvald, Y., Yee, J. C., Mroz, P., Poleski, R., Skowron, J., Szymanski, M. K., Soszynski, I., Kozlowski, S., Pietrukowicz, P., Ulaczyk, K., Pawlak, M., Albrow, M. D., Chung, S. -J., Han, C., Hwang, K. -H., Jung, Y. K., Ryu, Y. -H., Shin, I. -G., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., and Pogge, R. W.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

We analyze the binary gravitational microlensing event OGLE-2017-BLG-1130 (mass ratio q~0.45), the first published case in which the binary anomaly was only detected by the Spitzer Space Telescope. This event provides strong evidence that some binary signals can be missed by observations from the ground alone but detected by Spitzer. We therefore invert the normal procedure, first finding the lens parameters by fitting the space-based data and then measuring the microlensing parallax using ground-based observations. We also show that the normal four-fold space-based degeneracy in the single-lens case can become a weak eight-fold degeneracy in binary-lens events. Although this degeneracy is resolved in event OGLE-2017-BLG-1130, it might persist in other events., Comment: 14 pages, 5 figures

Published
2018
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33. OGLE-2017-BLG-1434Lb: Eighth q < 1 * 10^-4 Mass-Ratio Microlens Planet Confirms Turnover in Planet Mass-Ratio Function

Author

Udalski, A., Ryu, Y. -H., Sajadian, S., Gould, A., Mróz, P., Poleski, R., Szymański, M. K., Skowron, J., Soszyński, I., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., Pawlak, M., Rybicki, K., Iwanek, P., Albrow, M. D., Chung, S. -J., Han, C., Hwang, K. -H., Jung, Y. K., Shin, I. -G., Shvartzvald, Y., Yee, J. C., Zang, W., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., Pogge, R. W., Bozza, V., Dominik, M., Helling, C., Hundertmark, M., Jørgensen, U. G., Longa-Peña, P., Lowry, S., Burgdorf, M., Campbell-White, J., Ciceri, S., Evans, D., Jaimes, R. Figuera, Fujii, Y. I., Haikala, L. K., Henning, T., Hinse, T. C., Mancini, L., Peixinho, N., Rahvar, S., Rabus, M., Skottfelt, J., Snodgrass, C., Southworth, J., and von Essen, C.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery of a cold Super-Earth planet (m_p=4.4 +/- 0.5 M_Earth) orbiting a low-mass (M=0.23 +/- 0.03 M_Sun) M dwarf at projected separation a_perp = 1.18 +/- 0.10 AU, i.e., about 1.9 times the snow line. The system is quite nearby for a microlensing planet, D_Lens = 0.86 +/- 0.09 kpc. Indeed, it was the large lens-source relative parallax pi_rel=1.0 mas (combined with the low mass M) that gave rise to the large, and thus well-measured, "microlens parallax" that enabled these precise measurements. OGLE-2017-BLG-1434Lb is the eighth microlensing planet with planet-host mass ratio q < 1 * 10^-4. We apply a new planet-detection sensitivity method, which is a variant of "V/V_max", to seven of these eight planets to derive the mass-ratio function in this regime. We find dN/d(ln q) ~ q^p, with p = 1.05 (+0.78,-0.68), which confirms the "turnover" in the mass function found by Suzuki et al. relative to the power law of opposite sign n = -0.93 +/- 0.13 at higher mass ratios q >~ 2 * 10^-4. We combine our result with that of Suzuki et al. to obtain p = 0.73 (+0.42,-0.34)., Comment: 53 pages, 16 figures

Published
2018
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34. A Gravitationally Lensed Quasar Discovered in OGLE

Author

Kostrzewa-Rutkowska, Z., Kozłowski, S., Lemon, C., Anguita, T., Greiner, J., Auger, M. W., Wyrzykowski, Ł., Apostolovski, Y., Bolmer, J., Udalski, A., Szymański, M. K., Soszyński, I., Poleski, R., Pietrukowicz, P., Skowron, J., Mróz, P., Ulaczyk, K., and Pawlak, M.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We report the discovery of a new gravitationally lensed quasar (double) from the Optical Gravitational Lensing Experiment (OGLE) identified inside the $\sim$670 sq. deg area encompassing the Magellanic Clouds. The source was selected as one of $\sim$60 "red W1-W2" mid-IR objects from WISE and having a significant amount of variability in OGLE for both two (or more) nearby sources. This is the first detection of a gravitational lens, where the discovery is made "the other way around", meaning we first measured the time delay between the two lensed quasar images of $-132

Published
2018
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35. OGLE Collection of Star Clusters. New Objects in the Magellanic Bridge and the Outskirts of the Small Magellanic Cloud

Author

Sitek, M., Szymański, M. K., Udalski, A., Skowron, D. M., Kostrzewa-Rutkowska, Z., Skowron, J., Karczmarek, P., Cieślar, M., Wyrzykowski, Ł., Kozłowski, S., Pietrukowicz, P., Soszyński, I., Mróz, P., Pawlak, M., Poleski, R., and Ulaczyk, K.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

The Magellanic System (MS) encompasses the nearest neighbors of the Milky Way, the Large (LMC) and Small (SMC) Magellanic Clouds, and the Magellanic Bridge (MBR). This system contains a diverse sample of star clusters. Their parameters, such as the spatial distribution, chemical composition and age distribution yield important information about the formation scenario of the whole Magellanic System. Using deep photometric maps compiled in the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV) we present the most complete catalog of star clusters in the Magellanic System ever constructed from homogeneous, long time-scale photometric data. In this second paper of the series, we show the collection of star clusters found in the area of about 360 square degrees in the MBR and in the outer regions of the SMC. Our sample contains 198 visually identified star cluster candidates, 75 of which were not listed in any of the previously published catalogs. The new discoveries are mainly young small open clusters or clusters similar to associations., Comment: 16 pages, 6 figures

Published
2018
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36. Spitzer Microlensing Parallax for OGLE-2016-BLG-1067: a sub-Jupiter Orbiting an M-dwarf in the Disk

Author

Novati, S. Calchi, Suzuki, D., Udalski, A., Gould, A., Shvartzvald, Y., Bozza, V., Bennett, D. P., Beichman, C., Bryden, G., Carey, S., Gaudi, B. S., Henderson, C. B., Yee, J. C., Zhu, W., Abe, F., Asakura, Y., Barry, R., Bhattacharya, A., Bond, I. A., Donachie, M., Evans, P., Fukui, A., Hirao, Y., Itow, Y., Kawasaki, K., Koshimoto, N., Li, M. C. A., Ling, C. H., Matsubara, Y., Miyazaki, S., Muraki, Y., Nagakane, M., Ohnishi, K., Ranc, C., Rattenbury, N. J., Saito, To., Sharan, A., Sullivan, D. J., Sumi, T., Tristram, P. J., Yamada, T., Yonehara, A., Mróz, P., Poleski, R., Skowron, J., Szymański, M. K., Soszyński, I., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., Pawlak, M., Albrow, M. D., Chung, S. -J., Han, C., Hwang, K. -H., Jung, Y. K., Ryu, Y. -H., Shin, I. -G., Zang, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., and Pogge, R. W.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery of a sub-Jupiter mass planet orbiting beyond the snow line of an M-dwarf most likely in the Galactic disk as part of the joint Spitzer and ground-based monitoring of microlensing planetary anomalies toward the Galactic bulge. The microlensing parameters are strongly constrained by the light curve modeling and in particular by the Spitzer-based measurement of the microlens parallax, $\pi_\mathrm{E}$. However, in contrast to many planetary microlensing events, there are no caustic crossings, so the angular Einstein radius, $\theta_\mathrm{E}$ has only an upper limit based on the light curve modeling alone. Additionally, the analysis leads us to identify 8 degenerate configurations: the four-fold microlensing parallax degeneracy being doubled by a degeneracy in the caustic structure present at the level of the ground-based solutions. To pinpoint the physical parameters, and at the same time to break the parallax degeneracy, we make use of a series of arguments: the $\chi^2$ hierarchy, the Rich argument, and a prior Galactic model. The preferred configuration is for a host at $D_L=3.73_{-0.67}^{+0.66}~\mathrm{kpc}$ with mass $M_\mathrm{L}=0.30_{-0.12}^{+0.15}~\mathrm{M_\odot}$, orbited by a Saturn-like planet with $M_\mathrm{planet}=0.43_{-0.17}^{+0.21}~\mathrm{M_\mathrm{Jup}}$ at projected separation $a_\perp = 1.70_{-0.39}^{+0.38}~\mathrm{au}$, about 2.1 times beyond the system snow line. Therefore, it adds to the growing population of sub-Jupiter planets orbiting near or beyond the snow line of M-dwarfs discovered by microlensing. Based on the rules of the real-time protocol for the selection of events to be followed up with Spitzer, this planet will not enter the sample for measuring the Galactic distribution of planets., Comment: Submitted to AAS Journals

Published
2018
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37. OGLE-2016-BLG-1045: A Test of Cheap Space-Based Microlens Parallaxes

Author

Shin, I. -G., Udalski, A., Yee, J. C., Novati, S. Calchi, Christie, G., Poleski, R., Mróz, P., Skowron, J., Szymański, M. K., Soszyński, I., Pietrukowicz, P., Kozłowski, S., Ulaczyk, K., Pawlak, M., Natusch, T., Pogge, R. W., Gould, A., Han, C., Albrow, M. D., Chung, S. -J., Hwang, K. -H., Ryu, Y. -H., Jung, Y. K., Zhu, W., Lee, C. -U., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, Y., Lee, D. -J., Park, B. -G., Beichman, C., Bryden, G., Carey, S., Gaudi, B. S., Henderson, C. B., and Shvartzvald, Y.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Microlensing is a powerful and unique technique to probe isolated objects in the Galaxy. To study the characteristics of these interesting objects based on the microlensing method, measurement of the microlens parallax is required to determine the properties of the lens. Of the various methods to measure microlens parallax, the most robust way is to make simultaneous ground- and space-based observations, i.e., by measuring the space-based microlens parallax. However, space-based campaigns usually require "expensive" resources. Gould & Yee (2012) proposed an idea called the "cheap space-based microlens parallax" that can measure the lens-parallax using only $2$ or $3$ space-based observations of high-magnification events. This cost-effective observation strategy to measure microlens parallaxes could be used by space-borne telescopes to build a complete sample for studying isolated objects. This would enable a direct measurement of the mass function including both extremely low-mass objects and high-mass stellar remnants. However, to adopt this idea requires a test to check how it would work in actual situations. Thus, we present the first practical test of the idea using the high-magnification microlensing event OGLE-2016-BLG-1045, for which a subset of Spitzer observations fortuitously duplicate the prescription of Gould & Yee (2012). From the test, we confirm that the measurement of the lens-parallax adopting this idea has sufficient accuracy to determine the physical properties of the isolated lens., Comment: 7 Figures and 2 Tables, Accepted for publication in the ApJ

Published
2017
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38. A Neptune-mass Free-floating Planet Candidate Discovered by Microlensing Surveys

Author

Mroz, Przemek, Ryu, Y. -H., Skowron, J., Udalski, A., Gould, A., Szymanski, M. K., Soszynski, I., Poleski, R., Pietrukowicz, P., Kozlowski, S., Pawlak, M., Ulaczyk, K., Albrow, M. D., Chung, S. -J., Jung, Y. K., Han, C., Hwang, K. -H., Shin, I. -G., Yee, J. C., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., and Pogge, R. W.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Current microlensing surveys are sensitive to free-floating planets down to Earth-mass objects. All published microlensing events attributed to unbound planets were identified based on their short timescale (below two days), but lacked an angular Einstein radius measurement (and hence lacked a significant constraint on the lens mass). Here, we present the discovery of a Neptune-mass free-floating planet candidate in the ultrashort ($t_{\rm E}=0.320\pm0.003$ days) microlensing event OGLE-2016-BLG-1540. The event exhibited strong finite-source effects, which allowed us to measure its angular Einstein radius of $\theta_{\rm E}=9.2\pm0.5\,\mu$as. There remains, however, a degeneracy between the lens mass and distance. The combination of the source proper motion and source-lens relative proper motion measurements favors a Neptune-mass lens located in the Galactic disk. However, we cannot rule out that the lens is a Saturn-mass object belonging to the bulge population. We exclude stellar companions up to 15 au., Comment: accepted to AJ

Published
2017
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39. The OGLE Collection of Variable Stars. Classical, Type II, and Anomalous Cepheids toward the Galactic Center

Author

Soszyński, I., Udalski, A., Szymański, M. K., Wyrzykowski, Ł., Ulaczyk, K., Poleski, R., Pietrukowicz, P., Kozlowski, S., Skowron, D., Skowron, J., Mróz, P., Pawlak, M., Rybicki, K., and Jacyszyn-Dobrzeniecka, A.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present a collection of classical, type II, and anomalous Cepheids detected in the OGLE fields toward the Galactic center. The sample contains 87 classical Cepheids pulsating in one, two or three radial modes, 924 type II Cepheids divided into BL Her, W Vir, peculiar W Vir, and RV Tau stars, and 20 anomalous Cepheids - first such objects found in the Galactic bulge. Additionally, we upgrade the OGLE Collection of RR Lyr stars in the Galactic bulge by adding 828 newly identified variables. For all Cepheids and RR Lyr stars, we publish time-series VI photometry obtained during the OGLE-IV project, from 2010 through 2017. We discuss basic properties of our classical pulsators: their spatial distribution, light curve morphology, period-luminosity relations, and position in the Petersen diagram. We present the most interesting individual objects in our collection: a type II Cepheid with additional eclipsing modulation, W Vir stars with the period doubling effect and the RVb phenomenon, a mode-switching RR Lyr star, and a triple-mode anomalous RRd star., Comment: 20 pages, 12 figures

Published
2017
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40. OGLE-2015-BLG-1459L: The Challenges of Exo-Moon Microlensing

Author

Hwang, K. -H., Udalski, A., Bond, I. A., Albrow, M. D., Chung, S. -J., Gould, A., Han, C., Jung, Y. K., Ryu, Y. -H., Shin, I. -G., Yee, J. C., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., Pogge, R. W., Pawlak, M., Poleski, R., Szymański, M. K., Skowron, J., Soszyński, I., Mróz, P., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., Abe, F., Asakura, Y., Barry, R., Bennett, D. P., Bhattacharya, A., Donachie, M., Evans, P., Fukui, A., Hirao, Y., Itow, Y., Kawasaki, K., Koshimoto, N., Li, M. C. A., Ling, C. H., Masuda, K., Matsubara, Y., Miyazaki, S., Muraki, Y., Nagakane, M., Ohnishi, K., Ranc, C., Rattenbury, N. J., Saito, To., Sharan, A., Sullivan, D. J., Sumi, T., Suzuki, D., Tristram, P. J., Yamada, T., and Yonehara, A.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We show that dense OGLE and KMTNet $I$-band survey data require four bodies (sources plus lenses) to explain the microlensing light curve of OGLE-2015-BLG-1459. However, these can equally well consist of three lenses and one source (3L1S), two lenses and two sources (2L2S) or one lens and three sources (1L3S). In the 3L1S and 2L2S interpretations, the host is a brown dwarf and the dominant companion is a Neptune-class planet, with the third body (in the 3L1S case) being a Mars-class object that could have been a moon of the planet. In the 1L3S solution, the light curve anomalies are explained by a tight (five stellar radii) low-luminosity binary source that is offset from the principal source of the event by $\sim 0.17\,\au$. These degeneracies are resolved in favor of the 1L3S solution by color effects derived from comparison to MOA data, which are taken in a slightly different ($R/I$) passband. To enable current and future ($WFIRST$) surveys to routinely characterize exomoons and distinguish among such exotic systems requires an observing strategy that includes both a cadence faster than 9 min$^{-1}$ and observations in a second band on a similar timescale., Comment: 29 pages, 8 figures, accepted for publication in AJ

Published
2017
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41. OGLE-2016-BLG-1190Lb: First Spitzer Bulge Planet Lies Near the Planet/Brown-Dwarf Boundary

Author

Ryu, Y. -H., Yee, J. C., Udalski, A., Bond, I. A., Shvartzvald, Y., Zang, W., Jaimes, R. Figuera, Jorgensen, U. G., Zhu, W., Huang, C. X., Jung, Y. K., Albrow, M. D., Chung, S. -J., Gould, A., Han, C., Hwang, K. -H., Shin, I. -G., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., Pogge, R. W., Novati, S. Calchi, Carey, S., Henderson, C. B., Beichman, C., Gaudi, B. S., Mróz, P., Poleski, R., Skowron, J., Szymanski, M. K., Soszynski, I., Kozlowski, S., Pietrukowicz, P., Ulaczyk, K., Pawlak, M., Abe, F., Asakura, Y., Barry, R., Bennett, D. P., Bhattacharya, A., Donachie, M., Evans, P., Fukui, A., Hirao, Y., Itow, Y., Kawasaki, K., Koshimoto, N., Li, M. C. A., Ling, C. H., Masuda, K., Matsubara, Y., Miyazaki, S., Muraki, Y., Nagakane, M., Ohnishi, K., Ranc, C., Rattenbury, N. J., Saito, To., Sharan, A., Sullivan, D. J., Sumi, T., Suzuki, D., Tristram, P. J., Yamada, T., Yonehara, A., Bryden, G., Howell, S. B., Jacklin, S., Penny, M. T., Mao, S., Fouque, Pascal, Wang, T., Street, R. A., Tsapras, Y., Hundertmark, M., Bachelet, E., Dominik, M., Li, Z., Cross, S., Cassan, A., Horne, K., Schmidt, R., Wambsganss, J., Ment, S. K., Maoz, D., Snodgrass, C., Steele, I. A., Bozza, V., Burgdorf, M. J., Ciceri, S., D'Ago, G., Evans, D. F., Hinse, T. C., Kerins, E., Kokotanekova, R., Longa, P., MacKenzie, J., Popovas, A., Rabus, M., Rahvar, S., Sejadian, S., Skottfelt, J., Southworth, J., and von Essen, C.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass M_p= 13.4+-0.9 M_J places it right at the deuterium burning limit, i.e., the conventional boundary between "planets" and "brown dwarfs". Its existence raises the question of whether such objects are really "planets" (formed within the disks of their hosts) or "failed stars" (low mass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf M_host = 0.89+-0.07 M_sun and the planet has a semi-major axis a~2.0 AU. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultra-dense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over <1% of an orbital period., Comment: 63 pages, 13 figures, 7 tables, AJ, in press

Published
2017
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42. Radiation intensity dependence of CdSe photothermal and photocarrier radiometry response evidenced by step-sine modulation method.

Author

Chirtoc, M., Pawlak, M., and Horny, N.

Subjects
*INFRARED radiometry, *RADIOMETRY, *RADIATION, *SINGLE crystals, *PHOTOEXCITATION, *PHOTOLUMINESCENCE
Abstract

The radiation intensity dependence of photothermal (PT) and photocarrier (PC) signals from n-type CdSe single crystals was investigated by modulated infrared radiometry (MIRR) in the mid-IR range (5–11.3 μm) with superbandgap photoexcitation. The influence of dc temperature increase of the sample was avoided by a new step-sine modulation method that combines the advantages of transient and periodical modulation. With increasing laser intensity I, the amplitude of the PC component shows a sub-linear dependence (|SPC| ∝ I0.5), while the PT one has the expected linear dependence (|SPT| ∝ I). As a result, the transition frequency ft between the two components is shifted to higher frequencies, which is explained in the frame of a simple model. The origin of the observed effects is the decrease of the effective photocarrier lifetime τ ∝ I−0.5 over three laser intensity decades. In contrast, previous studies on nonlinear PC response in semiconductors performed in the near-IR range (0.7–1.8 μm) have found supra-linear |SPC| dependence with exponent between 1 and 2. This difference is attributed to the fact that the near-IR radiometric signal features characteristics of a photoluminescence (PL) signal that are different from those of the mid-IR PC signal, as shown in our previous study [J. Appl. Phys. 119, 125108 (2016)] on the same CdSe samples. [ABSTRACT FROM AUTHOR]

Published
2023
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43. Hydrogen-rich supernovae beyond the neutrino-driven core-collapse paradigm

Author

Terreran, G., Pumo, M. L., Chen, T. -W., Moriya, T. J., Taddia, F., Dessart, L., Zampieri, L., Smartt, S. J., Benetti, S., Inserra, C., Cappellaro, E., Nicholl, M., Fraser, M., Wyrzykowski, Ł., Udalski, A., Howell, D. A., McCully, C., Valenti, S., Dimitriadis, G., Maguire, K., Sullivan, M., Smith, K. W., Yaron, O., Young, D. R., Anderson, J. P., Della Valle, M., Elias-Rosa, N., Gal-Yam, A., Jerkstrand, A., Kankare, E., Pastorello, A., Sollerman, J., Turatto, M., Kostrzewa-Rutkowska, Z., Kozłowski, S., Mróz, P., Pawlak, M., Pietrukowicz, P., Poleski, R., Skowron, D., Skowron, J., Soszyński, I., Szymański, M. K., and Ulaczyk, K.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present our study of OGLE-2014-SN-073, one of the brightest Type II SN ever discovered, with an unusually broad lightcurve combined with high ejecta velocities. From our hydrodynamical modelling we infer a remarkable ejecta mass of $60^{+42}_{-16}$~M$_\odot$, and a relatively high explosion energy of $12.4^{+13.0}_{-5.9} \times10^{51}$~erg. We show that this object belongs, with a very small number of other hydrogen-rich SNe, to an energy regime that is not explained by standard core-collapse (CC) neutrino-driven explosions. We compare the quantities inferred by the hydrodynamical modelling with the expectations of various exploding scenarios, trying to explain the high energy and luminosity released. We find some qualitative similarities with pair-instabilities SNe, although a prompt injection of energy by a magnetar seems also a viable alternative to explain such extreme event., Comment: 49 pages, 10 figure, including Methods and Supplementary Information. Accepted for publication on Nature Astronomy

Published
2017

44. An Isolated Microlens Observed from K2, Spitzer and Earth

Author

Zhu, Wei, Udalski, A., Huang, C., Novati, S. Calchi, Sumi, T., Poleski, R., Skowron, J., Mroz, P., Szymanski, M. K., Soszynski, I., Pietrukowicz, P., Kozlowski, S., Ulaczyk, K., Pawlak, M., Beichman, C, Bryden, G., Carey, S., Gaudi, B. S., Gould, A., Henderson, C. B., Shvartzvald, Y., Yee, J. C., Bond, I. A., Bennett, D. P., Suzuki, D., Rattenbury, N. J., Koshimoto, N., Abe, F., Asakura, Y., Barry, R. K., Bhattacharya, A., Donachie, M., Evans, P., Fukui, A., Hirao, Y., Itow, Y., Kawasaki, K., Li, M. C. A., Ling, C. H., Masuda, K., Matsubara, Y., Miyazaki, S., Munakata, H., Muraki, Y., Nagakane, M., Ohnishi, K., Ranc, C., Saito, To., Sharan, A., Sullivan, D. J., Tristram, P. J., Yamada, T., and Yonehara, A.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

We present the result of microlensing event MOA-2016-BLG-290, which received observations from the two-wheel Kepler (K2), Spitzer, as well as ground-based observatories. A joint analysis of data from K2 and the ground leads to two degenerate solutions of the lens mass and distance. This degeneracy is effectively broken once the (partial) Spitzer light curve is included. Altogether, the lens is found to be an extremely low-mass star located in the Galactic bulge. MOA-2016-BLG-290 is the first microlensing event for which we have signals from three well-separated ($\sim1$ AU) locations. It demonstrates the power of two-satellite microlensing experiment in reducing the ambiguity of lens properties, as pointed out independently by S. Refsdal and A. Gould several decades ago., Comment: 8 pages, 4 figures, 1 table; submitted to ApJ Letters

Published
2017
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45. OGLE-2017-BLG-0173Lb: Low Mass-Ratio Planet in a 'Hollywood' Microlensing Event

Author

Hwang, K. -H., Udalski, A., Shvartzvald, Y., Ryu, Y. -H., Albrow, M. D., Chung, S. -J., Gould, A., Han, C., Jung, Y. K., Shin, I. -G., Yee, J. C., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, D. -J., Lee, Y., Park, B. -G., Pogge, R. W., Skowron, J., Mroz, P., Poleski, R., Kozlowski, S., Soszynski, I., Pietrukowicz, P., Szymanski, M. K., Ulaczyk, K., Pawlak, M., Bryden, G., Beichman, C., Novati, S. Calchi, Gaudi, B. S., Henderson, C. B., Jacklin, S., and Penny, M. T.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We present microlensing planet OGLE-2017-BLG-0173Lb, with planet-host mass ratio either $q\simeq 2.5\times 10^{-5}$ or $q\simeq 6.5\times 10^{-5}$, the lowest or among the lowest ever detected. The planetary perturbation is strongly detected, $\Delta\chi^2\sim 10,000$, because it arises from a bright (therefore, large) source passing over and enveloping the planetary caustic: a so-called "Hollywood" event. The factor $\sim 2.5$ offset in $q$ arises because of a previously unrecognized discrete degeneracy between Hollywood events in which the caustic is fully enveloped and those in which only one flank is enveloped, which we dub "Cannae" and "von Schlieffen", respectively. This degeneracy is "accidental" in that it arises from gaps in the data. Nevertheless, the fact that it appears in a $\Delta\chi^2=10,000$ planetary anomaly is striking. We present a simple formalism to estimate the sensitivity of other Hollywood events to planets and show that they can lead to detections close to, but perhaps not quite reaching, the Earth/Sun mass ratio of $3\times 10^{-6}$. This formalism also enables an analytic understanding of the factor $\sim 2.5$ offset in $q$ between the Cannae and von Schlieffen solutions. The Bayesian estimates for the host-mass, system distance, and planet-host projected separation are $M=0.39^{+0.40}_{-0.24}\,M_\odot$, $D_L=4.8^{+1.5}_{-1.8}\,\kpc$, and $a_\perp=3.8\pm 1.6\,\au$. The two estimates of the planet mass are $m_p=3.3^{+3.8}_{-2.1}\,M_\oplus$ and $m_p=8^{+11}_{-6}\,M_\oplus$. The measured lens-source relative proper motion $\mu=6\,\masyr$ will permit imaging of the lens in about 15 years or at first light on adaptive-optics imagers on next-generation telescopes. These will allow to measure the host mass but probably cannot resolve the planet-host mass-ratio degeneracy., Comment: 30 pages, 9 figures, AJ in press

Published
2017
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46. OGLE-2016-BLG-0263L\lowercase{b}: Microlensing Detection of a Very Low-mass Binary Companion Through a Repeating Event Channel

Author

Han, C., Udalski, A., Gould, A., Bond, I. A., Albrow, M. D., Chung, S. -J., Jung, Y. K., Ryu, Y. -H., Shin, I. -G., Yee, J. C., Zhu, W., Cha, S. -M., Kim, S. -L., Kim, D. -J., Lee, C. -U., Lee, Y., Park, B. -G., Skowron, J., Mróz, P., Pietrukowicz, P., Kozłowski, S., Poleski, R., Szymański, M. K., Soszyński, I., Ulaczyk, K., Pawlak, M., Abe, F., Asakura, Y., Barry, R., Bennett, D. P., Bhattacharya, A., Donachie, M., Evans, P., Fukui, A., Hirao, Y., Itow, Y., Koshimoto, N., Li, M. C. A., Ling, C. H., Masuda, K., Matsubara, Y., Muraki, Y., Nagakane, M., Ohnishi, K., Ranc, C., Rattenbury, N. J., Saito, To., Sharan, A., Sullivan, D. J., Sumi, T., Suzuki, D., Tristram, P. J., Yamada, T., and Yonehara, A.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery of a planet-mass companion to the microlens OGLE-2016-BLG-0263L. Unlike most low-mass companions that were detected through perturbations to the smooth and symmetric light curves produced by the primary, the companion was discovered through the channel of a repeating event, in which the companion itself produced its own single-mass light curve after the event produced by the primary had ended. Thanks to the continuous coverage of the second peak by high-cadence surveys, the possibility of the repeating nature due to source binarity is excluded with a $96\%$ confidence level. The mass of the companion estimated by a Bayesian analysis is $M_{\rm p}=4.1_{-2.5}^{+6.5}\ M_{\rm J}$. The projected primary-companion separation is $a_\perp = 6.5^{+1.3}_{-1.9}$ au. The ratio of the separation to the snow-line distance of $a_\perp/a_{\rm sl}\sim 15.4$ corresponds to the region beyond Neptune, the outermost planet of the solar system. We discuss the importance of high-cadence surveys in expanding the range of microlensing detections of low-mass companions and future space-based microlensing surveys., Comment: 10 pages, 8 figures

Published
2017
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47. Ground-based parallax confirmed by Spitzer: binary microlensing event MOA-2015-BLG-020

Author

Wang, Tianshu, Zhu, Wei, Mao, Shude, Bond, I. A., Gould, A., Udalski, A., Sumi, T., Bozza, V., Ranc, C., Cassan, A., Yee, J. C., Han, C., Abe, F., Asakura, Y., Barry, R., Bennett, D. P., Bhattacharya, A., Donachie, M., Evans, P., Fukui, A., Hirao, Y., Itow, Y., Kawasaki, K., Koshimoto, N., Li, M. C. A., Ling, C. H., Masuda, K., Matsubara, Y., Miyazaki, S., Muraki, Y., Nagakane, M., Ohnishi, K., Rattenbury, N., Saito, To., Sharan, A., Shibai, H., Sullivan, D. J., Suzuki, D., Tristram, P. J., Yamada, T., Yonehara, A., Pawlak, M., Pietrukowicz, P., Poleski, R., Skowron, J., Soszynski, I., KozLowski, S., Mroz, P., Ulaczyk, K., Szymanski, M. K., Beichman, C., Bryden, G., Novati, S. Calchi, Carey, S., Fausnaugh, M., Gaudi, B. S., Henderson, C. B., Shvartzvald, Y., Wibking, B., Albrow, M. D., Chung, S. -J., Hwang, K. -H., Jung, Y. K., Ryu, Y. -H., Shin, I. -G., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Yee, Y., Park, B. -G., Pogge, R. W., Street, R. A., Tsapras, Y., Hundertmark, M., Bachelet, E., Dominik, M., Horne, K., Jaimes, R. Figuera, Wambsganss, J., Bramich, D. M., Schmidt, R., Snodgrass, C., Steele, I. A., and Menzies, J.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present the analysis of the binary gravitational microlensing event MOA-2015-BLG-020. The event has a fairly long timescale (about 63 days) and thus the light curve deviates significantly from the lensing model that is based on the rectilinear lens-source relative motion. This enables us to measure the microlensing parallax through the annual parallax effect. The microlensing parallax parameters constrained by the ground-based data are confirmed by the Spitzer observations through the satellite parallax method. By additionally measuring the angular Einstein radius from the analysis of the resolved caustic crossing, the physical parameters of the lens are determined. It is found that the binary lens is composed of two dwarf stars with masses $M_1 = 0.606 \pm 0.028M_\odot$ and $M_2 = 0.125 \pm 0.006M_\odot$ in the Galactic disk. Assuming the source star is at the same distance as the bulge red clump stars, we find the lens is at a distance $D_L = 2.44 \pm 0.10 kpc$. In the end, we provide a summary and short discussion of all published microlensing events in which the annual parallax effect is confirmed by other independent observations., Comment: 16 pages, 5 figures

Published
2017
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48. OGLE-2016-BLG-0693LB: Probing the Brown Dwarf Desert with Microlensing

Author

Ryu, Y. -H., Udalski, A., Yee, J. C., Albrow, M. D., Chung, S. -J., Gould, A., Han, C., Hwang, K. -H., Jung, Y. K., Shin, I. -G., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, Y., Park, B. -G., Pogge, R. W., Pietrukowicz, P., Kozlowski, S., Poleski, R., Skowron, J., Mroz, P., Szymanski, M. K., Soszynski, I., Pawlak, M., and Ulaczyk, K.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

We present an analysis of microlensing event OGLE-2016-BLG-0693, based on the survey-only microlensing observations by the OGLE and KMTNet groups. In order to analyze the light curve, we consider the effects of parallax, orbital motion, and baseline slope, and also refine the result using a Galactic model prior. From the microlensing analysis, we find that the event is a binary composed of a low-mass brown dwarf 49+-20 M_J companion and a K- or G-dwarf host, which lies at a distance 5.0+-0.6 kpc toward the Galactic bulge. The projected separation between the brown dwarf and its host star is less than 5 AU, and thus it is likely that the brown dwarf companion is located in the brown dwarf desert., Comment: 27 pages, 7 figures, 4 tables, Accepted for publication in AJ

Published
2017
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49. Concluding Henrietta Leavitt's Work on Classical Cepheids in the Magellanic System and Other Updates of the OGLE Collection of Variable Stars

Author

Soszyński, I., Udalski, A., Szymański, M. K., Wyrzykowski, Ł., Ulaczyk, K., Poleski, R., Pietrukowicz, P., Kozlowski, S., Skowron, D., Skowron, J., Mróz, P., and Pawlak, M.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

More than a century ago, Henrietta Leavitt discovered the first Cepheids in the Magellanic Clouds together with the famous period-luminosity relationship revealed by these stars, which soon after revolutionized our view of the Universe. Over the years, the number of known Cepheids in these galaxies has steadily increased with the breakthrough in the last two decades thanks to the new generation of large-scale long-term sky variability surveys. Here we present the final upgrade of the OGLE Collection of Cepheids in the Magellanic System which already contained the vast majority of known Cepheids. The updated collection now comprises 9649 classical and 262 anomalous Cepheids. Type-II Cepheids will be updated shortly. Thanks to high completeness of the OGLE survey the sample of classical Cepheids includes virtually all stars of this type in the Magellanic Clouds. Thus, the OGLE survey concludes the work started by Leavitt. Additionally, the OGLE sample of RR Lyrae stars in the Magellanic System has been updated. It now counts 46 443 variables. A collection of seven anomalous Cepheids in the halo of our Galaxy detected in front of the Magellanic Clouds is also presented. OGLE photometric data are available to the astronomical community from the OGLE Internet Archive. The time-series photometry of all pulsating stars in the OGLE Collection has been supplemented with new observations., Comment: 11 pages, 3 figures

Published
2017
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50. Blue large-amplitude pulsators as a new class of variable stars

Author

Pietrukowicz, P., Dziembowski, W. A., Latour, M., Angeloni, R., Poleski, R., di Mille, F., Soszynski, I., Udalski, A., Szymanski, M. K., Wyrzykowski, L., Kozlowski, S., Skowron, J., Skowron, D., Mroz, P., Pawlak, M., and Ulaczyk, K.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Regular intrinsic brightness variations observed in many stars are caused by pulsations. These pulsations provide information on the global and structural parameters of the star. The pulsation periods range from seconds to years, depending on the compactness of the star and properties of the matter that forms its outer layers. Here, we report the discovery of more than a dozen of previously unknown short-period variable stars: blue large-amplitude pulsators. These objects show very regular brightness variations with periods in the range of 20-40 min and amplitudes of 0.2-0.4 mag in the optical passbands. The phased light curves have a characteristic sawtooth shape, similar to the shape of classical Cepheids and RR Lyrae-type stars pulsating in the fundamental mode. The objects are significantly bluer than main sequence stars observed in the same fields, which indicates that all of them are hot stars. Follow-up spectroscopy confirms a high surface temperature of about 30,000 K. Temperature and colour changes over the cycle prove the pulsational nature of the variables. However, large-amplitude pulsations at such short periods are not observed in any known type of stars, including hot objects. Long-term photometric observations show that the variable stars are very stable over time. Derived rates of period change are of the order of 10^-7 per year and, in most cases, they are positive. According to pulsation theory, such large-amplitude oscillations may occur in evolved low-mass stars that have inflated helium-enriched envelopes. The evolutionary path that could lead to such stellar configurations remains unknown., Comment: Published in Nature Astronomy

Published
2017
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