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1. A Case for a Binary Black Hole System Revealed via Quasi-Periodic Outflows

Author

Pasham, Dheeraj R., Tombesi, Francesco, Sukova, Petra, Zajacek, Michal, Rakshit, Suvendu, Coughlin, Eric, Kosec, Peter, Karas, Vladimir, Masterson, Megan, Mummery, Andrew, Holoien, Thomas W. -S., Guolo, Muryel, Hinkle, Jason, Ripperda, Bart, Witzany, Vojtech, Shappee, Ben, Kara, Erin, Horesh, Assaf, van Velzen, Sjoert, Sfaradi, Itai, Kaplan, David L., Burger, Noam, Murphy, Tara, Remillard, Ronald, Steiner, James F., Wevers, Thomas, Arcodia, Riccardo, Buchner, Johannes, Merloni, Andrea, Malyali, Adam, Fabian, Andy, Fausnaugh, Michael, Daylan, Tansu, Altamirano, Diego, Payne, Anna, and Ferrara, E. C.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Binaries containing a compact object orbiting a supermassive black hole are thought to be precursors of gravitational wave events, but their identification has been extremely challenging. Here, we report quasi-periodic variability in X-ray absorption which we interpret as quasi-periodic outflows (QPOuts) from a previously low-luminosity active galactic nucleus after an outburst, likely caused by a stellar tidal disruption. We rule out several models based on observed properties and instead show using general relativistic magnetohydrodynamic simulations that QPOuts, separated by roughly 8.3 days, can be explained with an intermediate-mass black hole secondary on a mildly eccentric orbit at a mean distance of about 100 gravitational radii from the primary. Our work suggests that QPOuts could be a new way to identify intermediate/extreme-mass ratio binary candidates., Comment: Accepted for publication in Science Advances. We report a new supermassive black hole phenomenon that we call quasi-periodic outflows (QPOuts)

Published
2024
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2. Heavy-element production in a compact object merger observed by JWST

Author

Levan, Andrew J., Gompertz, Benjamin P., Salafia, Om Sharan, Bulla, Mattia, Burns, Eric, Hotokezaka, Kenta, Izzo, Luca, Lamb, Gavin P., Malesani, Daniele B., Oates, Samantha R., Ravasio, Maria Edvige, Rouco Escorial, Alicia, Schneider, Benjamin, Sarin, Nikhil, Schulze, Steve, Tanvir, Nial R., Ackley, Kendall, Anderson, Gemma, Brammer, Gabriel B., Christensen, Lise, Dhillon, Vikram S., Evans, Phil A., Fausnaugh, Michael, Fong, Wen-fai, Fruchter, Andrew S., Fryer, Chris, Fynbo, Johan P. U., Gaspari, Nicola, Heintz, Kasper E., Hjorth, Jens, Kennea, Jamie A., Kennedy, Mark R., Laskar, Tanmoy, Leloudas, Giorgos, Mandel, Ilya, Martin-Carrillo, Antonio, Metzger, Brian D., Nicholl, Matt, Nugent, Anya, Palmerio, Jesse T., Pugliese, Giovanna, Rastinejad, Jillian, Rhodes, Lauren, Rossi, Andrea, Saccardi, Andrea, Smartt, Stephen J., Stevance, Heloise F., Tohuvavohu, Aaron, van der Horst, Alexander, Vergani, Susanna D., Watson, Darach, Barclay, Thomas, Bhirombhakdi, Kornpob, Breedt, Elmé, Breeveld, Alice A., Brown, Alexander J., Campana, Sergio, Chrimes, Ashley A., D’Avanzo, Paolo, D’Elia, Valerio, De Pasquale, Massimiliano, Dyer, Martin J., Galloway, Duncan K., Garbutt, James A., Green, Matthew J., Hartmann, Dieter H., Jakobsson, Páll, Kerry, Paul, Kouveliotou, Chryssa, Langeroodi, Danial, Le Floc’h, Emeric, Leung, James K., Littlefair, Stuart P., Munday, James, O’Brien, Paul, Parsons, Steven G., Pelisoli, Ingrid, Sahman, David I., Salvaterra, Ruben, Sbarufatti, Boris, Steeghs, Danny, Tagliaferri, Gianpiero, Thöne, Christina C., de Ugarte Postigo, Antonio, and Kann, David Alexander

Published
2024
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3. A temperate Earth-sized planet with tidal heating transiting an M6 star

Author

Peterson, Merrin S., Benneke, Björn, Collins, Karen, Piaulet, Caroline, Crossfield, Ian J. M., Ali-Dib, Mohamad, Christiansen, Jessie L., Gagné, Jonathan, Faherty, Jackie, Kite, Edwin, Dressing, Courtney, Charbonneau, David, Murgas, Felipe, Cointepas, Marion, Almenara, Jose Manuel, Bonfils, Xavier, Kane, Stephen, Werner, Michael W., Gorjian, Varoujan, Roy, Pierre-Alexis, Shporer, Avi, Pozuelos, Francisco J., Socia, Quentin Jay, Cloutier, Ryan, Dietrich, Jamie, Irwin, Jonathan, Weiss, Lauren, Waalkes, William, Berta-Thomson, Zach, Evans, Thomas, Apai, Daniel, Parviainen, Hannu, Pallé, Enric, Narita, Norio, Howard, Andrew W., Dragomir, Diana, Barkaoui, Khalid, Gillon, Michaël, Jehin, Emmanuel, Ducrot, Elsa, Benkhaldoun, Zouhair, Fukui, Akihiko, Mori, Mayuko, Nishiumi, Taku, Kawauchi, Kiyoe, Ricker, George, Latham, David W., Winn, Joshua N., Seager, Sara, Isaacson, Howard, Bixel, Alex, Gibbs, Aidan, Jenkins, Jon M., Smith, Jeffrey C., Chavez, Jose Perez, Rackham, Benjamin V., Henning, Thomas, Gabor, Paul, Chen, Wen-Ping, Espinoza, Nestor, Jensen, Eric L. N., Collins, Kevin I., Schwarz, Richard P., Conti, Dennis M., Wang, Gavin, Kielkopf, John F., Mao, Shude, Horne, Keith, Sefako, Ramotholo, Quinn, Samuel N., Moldovan, Dan, Fausnaugh, Michael, Fűűrész, Gábor, and Barclay, Thomas

Published
2023
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4. Complex Modulation of Rapidly Rotating Young M Dwarfs: Adding Pieces to the Puzzle

Author

Günther, Maximilian N., Berardo, David A., Ducrot, Elsa, Murray, Catriona A., Stassun, Keivan G., Olah, Katalin, Bouma, L. G., Rappaport, Saul, Winn, Joshua N., Feinstein, Adina D., Matthews, Elisabeth C., Sebastian, Daniel, Rackham, Benjamin V., Seli, Bálint, Triaud, Amaury H. M. J., Gillen, Edward, Levine, Alan M., Demory, Brice-Olivier, Gillon, Michaël, Queloz, Didier, Ricker, George, Vanderspek, Roland K., Seager, Sara, Latham, David W., Jenkins, Jon M., Brasseur, C. E., Colón, Knicole D., Daylan, Tansu, Delrez, Laetitia, Fausnaugh, Michael, Garcia, Lionel J., Jayaraman, Rahul, Jehin, Emmanuel, Kristiansen, Martti H., Kruijssen, J. M. Diederik, Pedersen, Peter Philmann, Pozuelos, Francisco J., Rodriguez, Joseph E., Wohler, Bill, and Zhan, Zhuchang

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

New sets of young M dwarfs with complex, sharp-peaked, and strictly periodic photometric modulations have recently been discovered with Kepler/K2 (scallop shells) and TESS (complex rotators). All are part of star-forming associations, are distinct from other variable stars, and likely belong to a unified class. Suggested hypotheses include star spots, accreting dust disks, co-rotating clouds of material, magnetically constrained material, spots and misaligned disks, and pulsations. Here, we provide a comprehensive overview and add new observational constraints with TESS and SPECULOOS Southern Observatory (SSO) photometry. We scrutinize all hypotheses from three new angles: (1) we investigate each scenario's occurrence rates via young star catalogs; (2) we study the features' longevity using over one year of combined data; and (3) we probe the expected color dependency with multi-color photometry. In this process, we also revisit the stellar parameters accounting for activity effects, study stellar flares as activity indicators over year-long time scales, and develop toy models to simulate typical morphologies. We rule out most hypotheses, and only (i) co-rotating material clouds and (ii) spots and misaligned disks remain feasible - with caveats. For (i), co-rotating dust might not be stable enough, while co-rotating gas alone likely cannot cause percentage-scale features; and (ii) would require misaligned disks around most young M dwarfs. We thus suggest a unified hypothesis, a superposition of large-amplitude spot modulations and sharp transits of co-rotating gas clouds. While the complex rotators' mystery remains, these new observations add valuable pieces to the puzzle going forward., Comment: Accepted in The Astronomical Journal, 23 pages, 14 figures, 2 tables. This is the authors' version of the manuscript

Published
2020
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5. The TESS Mission Target Selection Procedure

Author

Fausnaugh, Michael, Morgan, Ed, Vanderspek, Roland, Pepper, Joshua, Burke, Christopher J., Levine, Alan M., Rudat, Alexander, Villaseñor, Jesus Noel S., Vezie, Michael, Goeke, Robert F., Ricker, George R., Latham, David W., Seager, S., Winn, Joshua N., Jenkins, Jon M., Bakos, G. Á., Barclay, Thomas, Berta-Thompson, Zachory K., Bouma, Luke G., Boyd, Patricia T., Brasseur, C. E., Burt, Jennifer, Caldwell, Douglas A., Charbonneau, David, Christensen-Dalsgaard, J., Clampin, Mark, Collins, Karen A., Colón, Knicole D., DeLee, Nathan, Dunham, Edward, Fleming, Scott W., Fong, William, Soto, Aylin Garcia, Gaudi, B. Scott, Guerrero, Natalia M., Hesse, Katharine, Holman, Matthew J., Huang, Chelsea X., Kaltenegger, Lisa, Lissauer, Jack J., McDermott, Scott, McLean, Brian, Mireles, Ismael, Mullally, Susan E., Oelkers, Ryan J., Paegert, Martin, Pál, András, Quintana, Elisa V., Rinehart, S. A., Rodriguez, David R., Rose, Mark, Sasselov, Dimitar D., Schlieder, Joshua E., Sha, Lizhou, Shporer, Avi, Smith, Jeffrey C., Stassun, Keivan G., Tenenbaum, Peter, Ting, Eric B., Torres, Guillermo, Twicken, Joseph D., Vanderburg, Andrew, Wohler, Bill, and Yu, Liang

Published
2021

6. A low-eccentricity migration pathway for a 13-h-period Earth analogue in a four-planet system

Author

Serrano, Luisa Maria, Gandolfi, Davide, Mustill, Alexander J., Barragán, Oscar, Korth, Judith, Dai, Fei, Redfield, Seth, Fridlund, Malcolm, Lam, Kristine W. F., Díaz, Matías R., Grziwa, Sascha, Collins, Karen A., Livingston, John H., Cochran, William D., Hellier, Coel, Bellomo, Salvatore E., Trifonov, Trifon, Rodler, Florian, Alarcon, Javier, Jenkins, Jon M., Latham, David W., Ricker, George, Seager, Sara, Vanderspeck, Roland, Winn, Joshua N., Albrecht, Simon, Collins, Kevin I., Csizmadia, Szilárd, Daylan, Tansu, Deeg, Hans J., Esposito, Massimiliano, Fausnaugh, Michael, Georgieva, Iskra, Goffo, Elisa, Guenther, Eike, Hatzes, Artie P., Howell, Steve B., Jensen, Eric L. N., Luque, Rafael, Mann, Andrew W., Murgas, Felipe, Osborne, Hannah L. M., Palle, Enric, Persson, Carina M., Rowden, Pam, Rudat, Alexander, Smith, Alexis M. S., Twicken, Joseph D., Van Eylen, Vincent, and Ziegler, Carl

Published
2022
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7. Possible anticorrelations between pulsation amplitudes and the disc growth of Be stars in giant-outbursting Be X-ray binaries.

Author

Niwano, Masafumi, Fausnaugh, Michael M, Lau, Ryan M, De, Kishalay, Soria, Roberto, Ricker, George R, Vanderspek, Roland, Ashley, Michael C B, Earley, Nicholas, Hankins, Matthew J, Kasliwal, Mansi M, Moore, Anna M, Soon, Jamie, Travouillon, Tony, Sasada, Mahito, Takahashi, Ichiro, Yatsu, Yoichi, and Kawai, Nobuyuki

Subjects
*STELLAR oscillations, *STELLAR rotation, *CIRCUMSTELLAR matter, *X-ray binaries, *LIGHT curves
Abstract

The mechanism of X-ray outbursts in Be X-ray binaries remains a mystery, and understanding their circumstellar discs is crucial for a solution of the mass-transfer problem. In particular, it is important to identify the Be star activities (e.g. pulsations) that cause mass ejection and, hence, disc formation. Therefore, we investigated the relationship between optical flux oscillations and the infrared (IR) excess in a sample of five Be X-ray binaries. Applying the Lomb–Scargle technique to high-cadence optical light curves from the Transiting Exoplanet Survey Satellite (⁠|${\it TESS}$|⁠), we detected several significant oscillation modes in the 3–24 h period range for each source. We also measured the IR excess (a proxy for disc growth) of those five sources, using J -band light curves from Palomar Gattini-IR. In four of the five sources, we found anticorrelations between the IR excess and the amplitude of the main flux oscillation modes. This result is inconsistent with the conventional idea that non-radial pulsations drive mass ejections. We propose an alternative scenario where internal temperature variations in the Be star cause transitions between pulsation-active and mass-ejection-active states. [ABSTRACT FROM AUTHOR]

Published
2024
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8. OGLE-2015-BLG-0845L: a low-mass M dwarf from the microlensing parallax and xallarap effects.

Author

(胡哲程), Zhecheng Hu, (祝伟), Wei Zhu, Gould, Andrew, Udalski, Andrzej, Sumi, Takahiro, (陈平), Ping Chen, Calchi Novati, Sebastiano, Yee, Jennifer C, Beichman, Charles A, Bryden, Geoffery, Carey, Sean, Fausnaugh, Michael, Gaudi, B Scott, Henderson, Calen B, Shvartzvald, Yossi, Wibking, Benjamin, Mróz, Przemek, Skowron, Jan, Poleski, Radosław, and Szymański, Michał K

Subjects
GRAVITATIONAL lenses, PARALLAX, MASS measurement, MICROLENSES, DATA analysis
Abstract

We present the analysis of the microlensing event OGLE-2015-BLG-0845, which was affected by both the microlensing parallax and xallarap effects. The former was detected via the simultaneous observations from the ground and Spitzer , and the latter was caused by the orbital motion of the source star in a relatively close binary. The combination of these two effects led to a mass measurement of the lens object, revealing a low-mass (⁠|$0.14 \pm 0.05 \, \mathrm{ M}_{\odot }$|⁠) M dwarf at the bulge distance (⁠|$7.6 \pm 1.0$| kpc). The source binary consists of a late F-type subgiant and a K-type dwarf of |$\sim 1.2$| and |$\sim 0.9 \mathrm{ M}_{\odot }$|⁠ , respectively, and the orbital period is |$70 \pm 10$| d. OGLE-2015-BLG-0845 is the first single-lens event in which the lens mass is measured via the binarity of the source. Given the abundance of binary systems as potential microlensing sources, the xallarap effect may not be a rare phenomenon. Our work thus highlights the application of the xallarap effect in the mass determination of microlenses, and the same method can be used to identify isolated dark lenses. [ABSTRACT FROM AUTHOR]

Published
2024
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9. A remnant planetary core in the hot-Neptune desert

Author

Armstrong, David J., Lopez, Théo A., Adibekyan, Vardan, Booth, Richard A., Bryant, Edward M., Collins, Karen A., Deleuil, Magali, Emsenhuber, Alexandre, Huang, Chelsea X., King, George W., Lillo-Box, Jorge, Lissauer, Jack J., Matthews, Elisabeth, Mousis, Olivier, Nielsen, Louise D., Osborn, Hugh, Otegi, Jon, Santos, Nuno C., Sousa, Sérgio G., Stassun, Keivan G., Veras, Dimitri, Ziegler, Carl, Acton, Jack S., Almenara, Jose M., Anderson, David R., Barrado, David, Barros, Susana C. C., Bayliss, Daniel, Belardi, Claudia, Bouchy, Francois, Briceño, César, Brogi, Matteo, Brown, David J. A., Burleigh, Matthew R., Casewell, Sarah L., Chaushev, Alexander, Ciardi, David R., Collins, Kevin I., Colón, Knicole D., Cooke, Benjamin F., Crossfield, Ian J. M., Díaz, Rodrigo F., Mena, Elisa Delgado, Demangeon, Olivier D. S., Dorn, Caroline, Dumusque, Xavier, Eigmüller, Philipp, Fausnaugh, Michael, Figueira, Pedro, Gan, Tianjun, Gandhi, Siddharth, Gill, Samuel, Gonzales, Erica J., Goad, Michael R., Günther, Maximilian N., Helled, Ravit, Hojjatpanah, Saeed, Howell, Steve B., Jackman, James, Jenkins, James S., Jenkins, Jon M., Jensen, Eric L. N., Kennedy, Grant M., Latham, David W., Law, Nicholas, Lendl, Monika, Lozovsky, Michael, Mann, Andrew W., Moyano, Maximiliano, McCormac, James, Meru, Farzana, Mordasini, Christoph, Osborn, Ares, Pollacco, Don, Queloz, Didier, Raynard, Liam, Ricker, George R., Rowden, Pamela, Santerne, Alexandre, Schlieder, Joshua E., Seager, Sara, Sha, Lizhou, Tan, Thiam-Guan, Tilbrook, Rosanna H., Ting, Eric, Udry, Stéphane, Vanderspek, Roland, Watson, Christopher A., West, Richard G., Wilson, Paul A., Winn, Joshua N., Wheatley, Peter, Villasenor, Jesus Noel, Vines, Jose I., and Zhan, Zhuchang

Published
2020
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10. A super-Earth and two sub-Neptunes transiting the nearby and quiet M dwarf TOI-270

Author

Günther, Maximilian N., Pozuelos, Francisco J., Dittmann, Jason A., Dragomir, Diana, Kane, Stephen R., Daylan, Tansu, Feinstein, Adina D., Huang, Chelsea X., Morton, Timothy D., Bonfanti, Andrea, Bouma, L. G., Burt, Jennifer, Collins, Karen A., Lissauer, Jack J., Matthews, Elisabeth, Montet, Benjamin T., Vanderburg, Andrew, Wang, Songhu, Winters, Jennifer G., Ricker, George R., Vanderspek, Roland K., Latham, David W., Seager, Sara, Winn, Joshua N., Jenkins, Jon M., Armstrong, James D., Barkaoui, Khalid, Batalha, Natalie, Bean, Jacob L., Caldwell, Douglas A., Ciardi, David R., Collins, Kevin I., Crossfield, Ian, Fausnaugh, Michael, Furesz, Gabor, Gan, Tianjun, Gillon, Michaël, Guerrero, Natalia, Horne, Keith, Howell, Steve B., Ireland, Michael, Isopi, Giovanni, Jehin, Emmanuël, Kielkopf, John F., Lepine, Sebastien, Mallia, Franco, Matson, Rachel A., Myers, Gordon, Palle, Enric, Quinn, Samuel N., Relles, Howard M., Rojas-Ayala, Bárbara, Schlieder, Joshua, Sefako, Ramotholo, Shporer, Avi, Suárez, Juan C., Tan, Thiam-Guan, Ting, Eric B., Twicken, Joseph D., and Waite, Ian A.

Published
2019
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11. Revealing AGNs through TESS variability.

Author

Treiber, Helena P, Hinkle, Jason T, Fausnaugh, Michael M, Shappee, Benjamin J, Kochanek, Christopher S, Vallely, Patrick J, Auchettl, Katie, Holoien, Thomas W-S, Payne, Anna V, and Dai, Xinyu

Subjects
SUPERMASSIVE black holes, LIGHT curves, BLACK holes, STELLAR luminosity function, ACTIVE galactic nuclei, ACTIVE galaxies, GALAXIES
Abstract

We used Transiting Exoplanet Survey Satellite (TESS) data to identify 29 candidate active galactic nuclei (AGNs) through their optical variability. The high-cadence, high-precision TESS light curves present an opportunity for the identification of AGNs, including those not selected through other methods. Of the candidates, we found that 18 have either previously been identified as AGNs in the literature or could have been selected based on emission-line diagnostics, mid-IR colours, or X-ray luminosity. AGNs in low-mass galaxies offer a unique window into supermassive black hole and galaxy co-evolution and 8 of the 29 candidates have estimated black hole masses ≲ 106 M⊙. The low-mass galaxies NGC 4395 and NGC 4449 are two of our five 'high-confidence' candidates. Since our initial sample largely draws from just nine TESS sectors, we expect to identify at least ∼45 more candidates in the TESS primary and extended mission data sets, of which ∼60 per cent will be new AGNs and ∼20 per cent will be in low-mass galaxies. [ABSTRACT FROM AUTHOR]

Published
2023
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12. TESS shines light on the origin of the ambiguous nuclear transient ASASSN-18el.

Author

Hinkle, Jason T, Kochanek, Christopher S, Shappee, Benjamin J, Vallely, Patrick J, Auchettl, Katie, Fausnaugh, Michael, Holoien, Thomas W-S, Treiber, Helena P, Payne, Anna V, Gaudi, B Scott, Stassun, Keivan G, Thompson, Todd A, Tonry, J L, and Villanueva, Steven

Subjects
SUPERMASSIVE black holes, ACTIVE galactic nuclei, LIGHT curves, ACTIVE galaxies
Abstract

We analyse high-cadence data from the Transiting Exoplanet Survey Satellite (TESS) of the ambiguous nuclear transient (ANT) ASASSN-18el. The optical changing-look phenomenon in ASASSN-18el has been argued to be due to either a drastic change in the accretion rate of the existing active galactic nucleus (AGN) or the result of a tidal disruption event (TDE). Throughout the TESS observations, short-time-scale stochastic variability is seen, consistent with an AGN. We are able to fit the TESS light curve with a damped-random-walk (DRW) model and recover a rest-frame variability amplitude of |$\hat{\sigma } = 0.93 \pm 0.02$| mJy and a rest-frame time-scale of |$\tau _{DRW} = 20^{+15}_{-6}$| d. We find that the estimated τ DRW for ASASSN-18el is broadly consistent with an apparent relationship between the DRW time-scale and central supermassive black hole mass. The large-amplitude stochastic variability of ASASSN-18el, particularly during late stages of the flare, suggests that the origin of this ANT is likely due to extreme AGN activity rather than a TDE. [ABSTRACT FROM AUTHOR]

Published
2023
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14. TESS Data for Asteroseismology: Photometry.

Author

Handberg, Rasmus, Lund, Mikkel N., White, Timothy R., Hall, Oliver J., Buzasi, Derek L., Pope, Benjamin J. S., Hansen, Jonas S., von Essen, Carolina, Carboneau, Lindsey, Huber, Daniel, Vanderspek, Roland K., Fausnaugh, Michael M., Tenenbaum, Peter, and Jenkins, Jon M.

Published
2021
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15. The TESS Objects of Interest Catalog from the TESS Prime Mission.

Author

Guerrero, Natalia M., Seager, S., Huang, Chelsea X., Vanderburg, Andrew, Soto, Aylin Garcia, Mireles, Ismael, Hesse, Katharine, Fong, William, Glidden, Ana, Shporer, Avi, Latham, David W., Collins, Karen A., Quinn, Samuel N., Burt, Jennifer, Dragomir, Diana, Crossfield, Ian, Vanderspek, Roland, Fausnaugh, Michael, Burke, Christopher J., and Ricker, George

Published
2021
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16. TOI-811b and TOI-852b: New Transiting Brown Dwarfs with Similar Masses and Very Different Radii and Ages from the TESS Mission.

Author

Carmichael, Theron W., Quinn, Samuel N., Zhou, George, Grieves, Nolan, Irwin, Jonathan M., Stassun, Keivan G., Vanderburg, Andrew M., Winn, Joshua N., Bouchy, Francois, Brasseur, Clara E., Briceńo, César, Caldwell, Douglas A., Charbonneau, David, Collins, Karen A., Colon, Knicole D., Eastman, Jason D., Fausnaugh, Michael, Fong, William, Fűrész, Gábor, and Huang, Chelsea

Published
2021
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17. TESS Data for Asteroseismology: Timing Verification.

Author

Essen, Carolina von, Lund, Mikkel N., Handberg, Rasmus, Sosa, Marina S., Gadeberg, Julie Thiim, Kjeldsen, Hans, Vanderspek, Roland K., Mortensen, Dina S., Mallonn, M., Mammana, L., Morgan, Edward H., Villaseńor, Jesus Noel S., Fausnaugh, Michael M., and Ricker, George R.

Published
2020
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18. Hot, rocky and warm, puffy super-Earths orbiting TOI-402 (HD 15337).

Author

Dumusque, Xavier, Turner, Oliver, Dorn, Caroline, Eastman, Jason D., Allart, Romain, Adibekyan, Vardan, Sousa, Sergio, Santos, Nuno C., Mordasini, Christoph, Bourrier, Vincent, Bouchy, François, Coffinet, Adrien, Davies, Misty D., Díaz, Rodrigo F., Fausnaugh, Michael M., Glidden, Ana, Guerrero, Natalia, Henze, Christopher E., Jenkins, Jon M., and Latham, David W.

Subjects
STELLAR activity, PLANETARY orbits, STELLAR photometry, PROBABILITY density function, GAUSSIAN processes, PLANETARY systems, LINEAR velocity
Abstract

Context. The Transiting Exoplanet Survey Satellite (TESS) is revolutionising the search for planets orbiting bright and nearby stars. In sectors 3 and 4, TESS observed TOI-402 (TIC-120896927), a bright V = 9.1 K1 dwarf also known as HD 15337, and found two transiting signals with periods of 4.76 and 17.18 days and radii of 1.90 and 2.21 R⊕, respectively. This star was observed prior to the TESS detection as part of the radial-velocity (RV) search for planets using the HARPS spectrometer, and 85 precise RV measurements were obtained before the launch of TESS over a period of 14 yr. Aims. In this paper, we analyse the HARPS RV measurements in hand to confirm the planetary nature of these two signals. Methods. HD 15337 happens to present a stellar activity level similar to the Sun, with a magnetic cycle of similar amplitude and RV measurements that are affected by stellar activity. By modelling this stellar activity in the HARPS radial velocities using a linear dependence with the calcium activity index log(RHK′) $\log(R^{\prime}_{\textrm{HK}})$ log (R HK ′) , we are able, with a periodogram approach, to confirm the periods and the planetary nature of TOI-402.01 and TOI-402.02. We then derive robust estimates from the HARPS RVs for the orbital parameters of these two planets by modelling stellar activity with a Gaussian process and using the marginalised posterior probability density functions obtained from our analysis of TESS photometry for the orbital period and time of transit. Results. By modelling TESS photometry and the stellar host characteristics, we find that TOI-402.01 and TOI-402.02 have periods of 4.75642 ± 0.00021 and 17.1784 ± 0.0016 days and radii of 1.70 ± 0.06 and 2.52 ± 0.11 R⊕ (precision 3.6 and 4.2%), respectively. By analysing the HARPS RV measurements, we find that those planets are both super-Earths with masses of 7.20 ± 0.81 and 8.79 ± 1.68 M⊕ (precision 11.3 and 19.1%), and small eccentricities compatible with zero at 2σ. Conclusions. Although having rather similar masses, the radii of these two planets are very different, putting them on different sides of the radius gap. By studying the temporal evolution under X-ray and UV (XUV) driven atmospheric escape of the TOI-402 planetary system, we confirm, under the given assumptions, that photo-evaporation is a plausible explanation for this radius difference. Those two planets, being in the same system and therefore being in the same irradiation environment are therefore extremely useful for comparative exoplanetology across the evaporation valley and thus bring constraints on the mechanisms responsible for the radius gap. [ABSTRACT FROM AUTHOR]

Published
2019
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20. Sn 2012au: A Golden Link Between Superluminous Supernovae and Their Lower-Luminosity Counterparts

Author

Milisavljevic, Danny, Soderberg, Alicia M., Margutti, Raffaella, Drout, Maria Rebecca, Marion, G. Howie, Sanders, Nathan Edward, Hsiao, Eric Y., Lunnan, Ragnhild, Chornock, Ryan, Fesen, Robert A., Parrent, Jerod T., Levesque, Emily M., Berger, Edo, Foley, Ryan J., Challis, Pete, Kirshner, Robert P., Dittmann, Jason Adam, Bieryla, Allyson, Kamble, Atish, Chakraborti, Sayan, De Rosa, Gisella, Fausnaugh, Michael, Hainline, Kevin N., Chen, Chien-Ting, Hickox, Ryan C., Morrell, Nidia, Phillips, Mark M., and Stritzinger, Maximilian

Subjects
supernovae: general, supernova: individual (SN 2012au)
Abstract

We present optical and near-infrared observations of SN 2012au, a slow-evolving supernova (SN) with properties that suggest a link between subsets of energetic and H-poor SNe and superluminous SNe. SN 2012au exhibited conspicuous SN Ib-like He I lines and other absorption features at velocities reaching ≈ 2×104 km s−1 in its early spectra, and a broad light curve that peaked at MB = −18.1 mag. Models of these data indicate a large explosion kinetic energy of ∼ 1052 erg and 56Ni mass ejection of MNi ≈ 0.3M⊙ on par with SN 1998bw. SN 2012au’s spectra almost one year after explosion show a blend of persistent Fe II P-Cyg absorptions and nebular emissions originating from two distinct velocity regions. These late-time emissions include strong [Fe II], [Ca II], [O I], Mg I], and Na I lines at velocities & 4500 km s−1, as well as O I and Mg I lines at noticeably smaller velocities . 2000 km s−1. Many of the late-time properties of SN 2012au are similar to the slow-evolving hypernovae SN 1997dq and SN 1997ef, and the superluminous SN 2007bi. Our observations suggest that a single explosion mechanism may unify all of these events that span −21 . MB . −17 mag. The aspherical and possibly jetted explosion was most likely initiated by the core collapse of a massive progenitor star and created substantial high-density, low-velocity Ni-rich material., Astronomy

Published
2013
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