Publication Search Results

ID: 159333
Type: article
Authors: 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.; Briceño, César; Caldwell, Douglas A.; Charbonneau, David; Collins, Karen A.; Colon, Knicole D.; Eastman, Jason D.; Fausnaugh, Michael; Fong, William; Fűrész, Gábor; Huang, Chelsea; Jenkins, Jon M.; Kielkopf, John F.; Latham, David W.; Law, Nicholas; Lund, Michael B.; Mann, Andrew W.; Ricker, George R.; Rodriguez, Joseph E.; Schwarz, Richard P.; Shporer, Avi; Tenenbaum, Peter; Wood, Mackenna L.; Ziegler, Carl
Abstract: We report the discovery of two transiting brown dwarfs (BDs), TOI-811b and TOI-852b, from NASA's Transiting Exoplanet Survey Satellite mission. These two transiting BDs have similar masses but very different radii and ages. Their host stars have similar masses, effective temperatures, and metallicities. The younger and larger transiting BD is TOI-811b at a mass of M_b = 59.9 ± 13.0M_J and radius of R_b = 1.26 ± 0.06R_J, and it orbits its host star in a period of P = 25.16551 ± 0.00004 days. We derive the host star's age of ${93}_{-29}^{+61}$ Myr from an application of gyrochronology. The youth of this system, rather than external heating from its host star, is why this BD's radius is relatively large. This constraint on the youth of TOI-811b allows us to test substellar mass-radius evolutionary models at young ages where the radius of BDs changes rapidly. TOI-852b has a similar mass at M_b = 53.7 ± 1.4M_J but is much older (4 or 8 Gyr, based on bimodal isochrone results of the host star) and is also smaller with a radius of R_b = 0.83 ± 0.04R_J. TOI-852b's orbital period is P = 4.94561 ± 0.00008 days. TOI-852b joins the likes of other old transiting BDs that trace out the oldest substellar mass-radius evolutionary models where contraction of the BD's radius slows and approaches a constant value. Both host stars have a mass of M_⋆ = 1.32M_⊙ ± 0.05 and differ in their radii, T_eff, and [Fe/H], with TOI-811 having R_⋆ = 1.27 ± 0.09R_⊙, T_eff = 6107 ± 77 K, and [Fe/H] = + 0.40 ± 0.09 and TOI-852 having R_⋆ = 1.71 ± 0.04R_⊙, T_eff = 5768 ± 84 K, and [Fe/H] = + 0.33 ± 0.09. We take this opportunity to examine how TOI-811b and TOI-852b serve as test points for young and old substellar isochrones, respectively.

ID: 159336
Type: article
Authors: Daylan, Tansu; Pinglé, Kartik; Wright, Jasmine; Günther, Maximilian N.; Stassun, Keivan G.; Kane, Stephen R.; Vanderburg, Andrew; Jontof-Hutter, Daniel; Rodriguez, Joseph E.; Shporer, Avi; Huang, Chelsea X.; Mikal-Evans, Thomas; Badenas-Agusti, Mariona; Collins, Karen A.; Rackham, Benjamin V.; Quinn, Samuel N.; Cloutier, Ryan; Collins, Kevin I.; Guerra, Pere; Jensen, Eric L. N.; Kielkopf, John F.; Massey, Bob; Schwarz, Richard P.; Charbonneau, David; Lissauer, Jack J.; Irwin, Jonathan M.; Baştürk, Özgür; Fulton, Benjamin; Soubkiou, Abderahmane; Zouhair, Benkhaldoun; Howell, Steve B.; Ziegler, Carl; Briceño, César; Law, Nicholas; Mann, Andrew W.; Scott, Nic; Furlan, Elise; Ciardi, David R.; Matson, Rachel; Hellier, Coel; Anderson, David R.; Butler, R. Paul; Crane, Jeffrey D.; Teske, Johanna K.; Shectman, Stephen A.; Kristiansen, Martti H.; Terentev, Ivan A.; Schwengeler, Hans Martin; Ricker, George R.; Vanderspek, Roland; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Berta-Thompson, Zachory K.; Bouma, Luke G.; Fong, William; Furesz, Gabor; Henze, Christopher E.; Morgan, Edward H.; Quintana, Elisa; Ting, Eric B.; Twicken, Joseph D.
Abstract: We report the discovery and validation of four extrasolar planets hosted by the nearby, bright, Sun-like (G3V) star HD 108236 using data from the Transiting Exoplanet Survey Satellite (TESS). We present transit photometry, reconnaissance, and precise Doppler spectroscopy, as well as high-resolution imaging, to validate the planetary nature of the objects transiting HD 108236, also known as the TESS Object of Interest (TOI) 1233. The innermost planet is a possibly rocky super-Earth with a period of ${3.79523}_{-0.00044}^{+0.00047}$ days and has a radius of 1.586 ± 0.098 R_⊕. The outer planets are sub-Neptunes, with potential gaseous envelopes, having radii of ${2.068}_{-0.091}^{+0.10}$ R_⊕, 2.72 ± 0.11 R_⊕, and ${3.12}_{-0.12}^{+0.13}$ R_⊕ and periods of ${6.20370}_{-0.00052}^{+0.00064}$ days, ${14.17555}_{-0.0011}^{+0.00099}$ days, and ${19.5917}_{-0.0020}^{+0.0022}$ days, respectively. With V and K_s magnitudes of 9.2 and 7.6, respectively, the bright host star makes the transiting planets favorable targets for mass measurements and, potentially, for atmospheric characterization via transmission spectroscopy. HD 108236 is the brightest Sun-like star in the visual (V) band known to host four or more transiting exoplanets. The discovered planets span a broad range of planetary radii and equilibrium temperatures and share a common history of insolation from a Sun-like star (R_⋆ = 0.888 ± 0.017 R_⊙, T_eff = 5730 ± 50 K), making HD 108236 an exciting, opportune cosmic laboratory for testing models of planet formation and evolution.

ID: 159324
Type: article
Authors: Hurt, Spencer A.; Quinn, Samuel N.; Latham, David W.; Vanderburg, Andrew; Esquerdo, Gilbert A.; Calkins, Michael L.; Berlind, Perry; Angus, Ruth; Latham, Christian A.; Zhou, George
Abstract: We present an analysis of 1524 spectra of Vega spanning 10 yr, in which we search for periodic radial-velocity variations. A signal with a periodicity of 0.676 day and a semi-amplitude of ∼10 m s^-1 is consistent with the rotation period measured over much shorter time spans by previous spectroscopic and spectropolarimetric studies, confirming the presence of surface features on this A0 star. The activity signal appears to evolve on long timescales, which may indicate the presence of failed fossil magnetic fields on Vega. TESS data reveal Vega's photometric rotational modulation for the first time, with a total amplitude of only 10 ppm. A comparison of the spectroscopic and photometric amplitudes suggests that the surface features may be dominated by bright plages rather than dark spots. For the shortest orbital periods, transit and radial-velocity injection recovery tests exclude the presence of transiting planets larger than 2 R_⊕ and most non-transiting giant planets. At long periods, we combine our radial velocities with direct imaging from the literature to produce detection limits for Vegan planets and brown dwarfs out to distances of 15 au. Finally, we detect a candidate radial-velocity signal with a period of 2.43 days and a semi-amplitude of 6 m s^-1. If caused by an orbiting companion, its minimum mass would be ∼20 M_⊕; because of Vega's pole-on orientation, this would correspond to a Jovian planet if the orbit is aligned with the stellar spin. We discuss the prospects for confirmation of this candidate planet.

ID: 159318
Type: article
Authors: Powell, Brian P.; Kostov, Veselin B.; Rappaport, Saul A.; Borkovits, Tamás; Zasche, Petr; Tokovinin, Andrei; Kruse, Ethan; Latham, David W.; Montet, Benjamin T.; Jensen, Eric L. N.; Jayaraman, Rahul; Collins, Karen A.; Mašek, Martin; Hellier, Coel; Evans, Phil; Tan, Thiam-Guan; Schlieder, Joshua E.; Torres, Guillermo; Smale, Alan P.; Friedman, Adam H.; Barclay, Thomas; Gagliano, Robert; Quintana, Elisa V.; Jacobs, Thomas L.; Gilbert, Emily A.; Kristiansen, Martti H.; Colón, Knicole D.; LaCourse, Daryll M.; Olmschenk, Greg; Omohundro, Mark; Schnittman, Jeremy D.; Schwengeler, Hans M.; Barry, Richard K.; Terentev, Ivan A.; Boyd, Patricia; Schmitt, Allan R.; Quinn, Samuel N.; Vanderburg, Andrew; Palle, Enric; Armstrong, James; Ricker, George R.; Vanderspek, Roland; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Caldwell, Douglas A.; Wohler, Bill; Shiao, Bernie; Burke, Christopher J.; Daylan, Tansu; Villaseñor, Joel
Abstract: We report the discovery of a sextuply eclipsing sextuple star system from TESS data, TIC 168789840, also known as TYC 7037-89-1, the first known sextuple system consisting of three eclipsing binaries. The target was observed in Sectors 4 and 5 during Cycle 1, with lightcurves extracted from TESS Full Frame Image data. It was also previously observed by the WASP survey and ASAS-SN. The system consists of three gravitationally bound eclipsing binaries in a hierarchical structure of an inner quadruple system with an outer binary subsystem. Follow-up observations from several different observatories were conducted as a means of determining additional parameters. The system was resolved by speckle interferometry with a 0"42 separation between the inner quadruple and outer binary, inferring an estimated outer period of ∼2 kyr. It was determined that the fainter of the two resolved components is an 8.217 day eclipsing binary, which orbits the inner quadruple that contains two eclipsing binaries with periods of 1.570 days and 1.306 days. Markov Chain Monte Carlo (MCMC) analysis of the stellar parameters has shown that the three binaries of TIC 168789840 are "triplets," as each binary is quite similar to the others in terms of mass, radius, and T_eff. As a consequence of its rare composition, structure, and orientation, this object can provide important new insight into the formation, dynamics, and evolution of multiple star systems. Future observations could reveal if the intermediate and outer orbital planes are all aligned with the planes of the three inner eclipsing binaries.

ID: 159316
Type: article
Authors: Rodriguez, Joseph E.; Quinn, Samuel N.; Zhou, George; Vanderburg, Andrew; Nielsen, Louise D.; Wittenmyer, Robert A.; Brahm, Rafael; Reed, Phillip A.; Huang, Chelsea X.; Vach, Sydney; Ciardi, David R.; Oelkers, Ryan J.; Stassun, Keivan G.; Hellier, Coel; Gaudi, B. Scott; Eastman, Jason D.; Collins, Karen A.; Bieryla, Allyson; Christian, Sam; Latham, David W.; Carleo, Ilaria; Wright, Duncan J.; Matthews, Elisabeth; Gonzales, Erica J.; Ziegler, Carl; Dressing, Courtney D.; Howell, Steve B.; Tan, Thiam-Guan; Wittrock, Justin; Plavchan, Peter; McLeod, Kim K.; Baker, David; Wang, Gavin; Radford, Don J.; Schwarz, Richard P.; Esposito, Massimiliano; Ricker, George R.; Vanderspek, Roland K.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Addison, Brett; Anderson, D. R.; Barclay, Thomas; Beatty, Thomas G.; Berlind, Perry; Bouchy, Francois; Bowen, Michael; Bowler, Brendan P.; Brasseur, C. E.; Briceño, César; Caldwell, Douglas A.; Calkins, Michael L.; Cartwright, Scott; Chaturvedi, Priyanka; Chaverot, Guillaume; Chimaladinne, Sudhish; Christiansen, Jessie L.; Collins, Kevin I.; Crossfield, Ian J. M.; Eastridge, Kevin; Espinoza, Néstor; Esquerdo, Gilbert A.; Feliz, Dax L.; Fenske, Tyler; Fong, William; Gan, Tianjun; Giacalone, Steven; Gill, Holden; Gordon, Lindsey; Granados, A.; Grieves, Nolan; Guenther, Eike W.; Guerrero, Natalia; Henning, Thomas; Henze, Christopher E.; Hesse, Katharine; Hobson, Melissa J.; Horner, Jonathan; James, David J.; Jensen, Eric L. N.; Jimenez, Mary; Jordán, Andrés; Kane, Stephen R.; Kielkopf, John; Kim, Kingsley; Kuhn, Rudolf B.; Latouf, Natasha; Law, Nicholas M.; Levine, Alan M.; Lund, Michael B.; Mann, Andrew W.; Mao, Shude; Matson, Rachel A.; Mengel, Matthew W.; Mink, Jessica; Newman, Patrick; O'Dwyer, Tanner; Okumura, Jack; Palle, Enric; Pepper, Joshua; Quintana, Elisa V.; Sarkis, Paula; Savel, Arjun B.; Schlieder, Joshua E.; Schnaible, Chloe; Shporer, Avi; Sefako, Ramotholo; Seidel, Julia V.; Siverd, Robert J.; Skinner, Brett; Stalport, Manu; Stevens, Daniel J.; Stibbards, Caitlin; Tinney, C. G.; West, R. G.; Yahalomi, Daniel A.; Zhang, Hui
Abstract: We present the discovery and characterization of five hot and warm Jupiters-TOI-628 b (TIC 281408474; HD 288842), TOI-640 b (TIC 147977348), TOI-1333 b (TIC 395171208, BD+47 3521A), TOI-1478 b (TIC 409794137), and TOI-1601 b (TIC 139375960)-based on data from NASA's Transiting Exoplanet Survey Satellite (TESS). The five planets were identified from the full-frame images and were confirmed through a series of photometric and spectroscopic follow-up observations by the TESS Follow-up Observing Program Working Group. The planets are all Jovian size (R_P = 1.01-1.77 R_J) and have masses that range from 0.85 to 6.33 M_J. The host stars of these systems have F and G spectral types (5595 ≤ T_eff ≤ 6460 K) and are all relatively bright (9.5 ≤ 6460 K) and are all relatively bright (9.5 ≤ 6460 K) and are all relatively bright (9.5 ≤ 6460 K) and are all relatively bright (9.5 ≤ 6460 K) and are all relatively bright (9.5 ≤ 6460 K) and are all relatively bright (9.5 _P > 1.7 R_J, possibly a result of its host star's evolution) and resides on an orbit with a period longer than 5 days. TOI-628 b is the most massive, hot Jupiter discovered to date by TESS with a measured mass of ${6.31}_{-0.30}^{+0.28}$ M_J and a statistically significant, nonzero orbital eccentricity of e = ${0.074}_{-0.022}^{+0.021}$ . This planet would not have had enough time to circularize through tidal forces from our analysis, suggesting that it might be remnant eccentricity from its migration. The longest-period planet in this sample, TOI-1478 b (P = 10.18 days), is a warm Jupiter in a circular orbit around a near-solar analog. NASA's TESS mission is continuing to increase the sample of well-characterized hot and warm Jupiters, complementing its primary mission goals.

ID: 159320
Type: article
Authors: Tofflemire, Benjamin M.; Rizzuto, Aaron C.; Newton, Elisabeth R.; Kraus, Adam L.; Mann, Andrew W.; Vanderburg, Andrew; Nelson, Tyler; Hawkins, Keith; Wood, Mackenna L.; Zhou, George; Quinn, Samuel N.; Howell, Steve B.; Collins, Karen A.; Schwarz, Richard P.; Stassun, Keivan G.; Bouma, Luke G.; Essack, Zahra; Osborn, Hugh; Boyd, Patricia T.; Fűrész, Gábor; Glidden, Ana; Twicken, Joseph D.; Wohler, Bill; McLean, Brian; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.
Abstract: The detection and characterization of young planetary systems offer a direct path to study the processes that shape planet evolution. We report on the discovery of a sub-Neptune-sized planet orbiting the young star HD 110082 (TOI-1098). Transit events we initially detected during TESS Cycle 1 are validated with time-series photometry from Spitzer. High-contrast imaging and high-resolution, optical spectra are also obtained to characterize the stellar host and confirm the planetary nature of the transits. The host star is a late-F dwarf (M_⋆ = 1.2M_⊙) with a low-mass, M dwarf binary companion (M_⋆ = 0.26M_⊙) separated by nearly one arcminute (∼6200 au). Based on its rapid rotation and Lithium absorption, HD 110082 is young, but is not a member of any known group of young stars (despite proximity to the Octans association). To measure the age of the system, we search for coeval, phase-space neighbors and compile a sample of candidate siblings to compare with the empirical sequences of young clusters and to apply quantitative age-dating techniques. In doing so, we find that HD 110082 resides in a new young stellar association we designate MELANGE-1, with an age of ${250}_{-70}^{+50}$ Myr. Jointly modeling the TESS and Spitzer light curves, we measure a planetary orbital period of 10.1827 days and radius of R_p = 3.2 ± 0.1R_⊕. HD 110082 b's radius falls in the largest 12% of field-age systems with similar host-star mass and orbital period. This finding supports previous studies indicating that young planets have larger radii than their field-age counterparts.

ID: 159422
Type: article
Authors: Trifonov, T.; Caballero, J. A.; Morales, J. C.; Seifahrt, A.; Ribas, I.; Reiners, A.; Bean, J. L.; Luque, R.; Parviainen, H.; Pallé, E.; Stock, S.; Zechmeister, M.; Amado, P. J.; Anglada-Escudé, G.; Azzaro, M.; Barclay, T.; Béjar, V. J. S.; Bluhm, P.; Casasayas-Barris, N.; Cifuentes, C.; Collins, Karen A.; Collins, K. I.; Cortés-Contreras, M.; de Leon, J.; Dreizler, S.; Dressing, C. D.; Esparza-Borges, E.; Espinoza, N.; Fausnaugh, M.; Fukui, A.; Hatzes, A. P.; Hellier, C.; Henning, Th; Henze, C. E.; Herrero, E.; Jeffers, S. V.; Jenkins, J. M.; Jensen, E. L. N.; Kaminski, A.; Kasper, D.; Kossakowski, D.; Kürster, M.; Lafarga, M.; Latham, David W.; Mann, A. W.; Molaverdikhani, K.; Montes, D.; Montet, B. T.; Murgas, F.; Narita, N.; Oshagh, M.; Passegger, V. M.; Pollacco, D.; Quinn, Samuel N.; Quirrenbach, A.; Ricker, G. R.; Rodríguez López, C.; Sanz-Forcada, J.; Schwarz, R. P.; Schweitzer, A.; Seager, S.; Shporer, A.; Stangret, M.; Stürmer, J.; Tan, T. G.; Tenenbaum, P.; Twicken, J. D.; Vanderspek, R.; Winn, J. N.
Abstract: Spectroscopy of transiting exoplanets can be used to investigate their atmospheric properties and habitability. Combining radial velocity (RV) and transit data provides additional information on exoplanet physical properties. We detect a transiting rocky planet with an orbital period of 1.467 days around the nearby red dwarf star Gliese 486. The planet Gliese 486 b is 2.81 Earth masses and 1.31 Earth radii, with uncertainties of 5%, as determined from RV data and photometric light curves. The host star is at a distance of ~8.1 parsecs, has a J-band magnitude of ~7.2, and is observable from both hemispheres of Earth. On the basis of these properties and the planet's short orbital period and high equilibrium temperature, we show that this terrestrial planet is suitable for emission and transit spectroscopy.

ID: 156870
Type: article
Authors: Bakos, G. Á.; Bayliss, D.; Bento, J.; Bhatti, W.; Brahm, R.; Csubry, Z.; Espinoza, N.; Hartman, J. D.; Henning, Th; Jordán, A.; Mancini, L.; Penev, K.; Rabus, M.; Sarkis, P.; Suc, V.; de Val-Borro, M.; Zhou, George; Butler, R. P.; Crane, J.; Durkan, S.; Shectman, S.; Kim, J.; Lázár, J.; Papp, I.; Sári, P.; Ricker, G.; Vanderspek, R.; Latham, David W.; Seager, S.; Winn, J. N.; Jenkins, J.; Chacon, A. D.; Fűrész, G.; Goeke, B.; Li, J.; Quinn, Samuel; Quintana, E. V.; Tenenbaum, P.; Teske, J.; Vezie, M.; Yu, L.; Stockdale, C.; Evans, P.; Relles, H. M.
Abstract: We report the discovery of HATS-71b, a transiting gas giant planet on a $P=3.7955$ day orbit around a $G=15.35$ mag M3 dwarf star. HATS-71 is the coolest M dwarf star known to host a hot Jupiter. The loss of light during transits is 4.7%, more than in any other confirmed transiting planet system. The planet was identified as a candidate by the ground- based HATSouth transit survey. It was confirmed using ground-based photometry, spectroscopy, and imaging, as well as space-based photometry from the NASA Transiting Exoplanet Survey Satellite mission (TIC 234523599). Combining all of these data, and utilizing Gaia DR2, we find that the planet has a radius of $1.024\pm 0.018$ ${R}_{{\rm{J}}}$ and mass of $0.37\,\pm 0.24$ ${M}_{{\rm{J}}}$ (95% confidence upper limit of $\lt 0.80$ ${M}_{{\rm{J}}}$ ), while the star has a mass of $0.4861\pm 0.0060$ ${M}_{\odot }$ and a radius of $0.4783\pm 0.0060$ ${R}_{\odot }$ .

ID: 158651
Type: article
Authors: Bouma, L. G.; Hartman, J. D.; Brahm, R.; Evans, P.; Collins, Karen A.; Zhou, George; Sarkis, P.; Quinn, Samuel N.; de Leon, J.; Livingston, J.; Bergmann, C.; Stassun, K. G.; Bhatti, W.; Winn, J. N.; Bakos, G. Á.; Abe, L.; Crouzet, N.; Dransfield, G.; Guillot, T.; Marie-Sainte, W.; Mékarnia, D.; Triaud, A. H. M. J.; Tinney, C. G.; Henning, T.; Espinoza, N.; Jordán, A.; Barbieri, M.; Nandakumar, S.; Trifonov, T.; Vines, J. I.; Vuckovic, M.; Ziegler, C.; Law, N.; Mann, A. W.; Ricker, G. R.; Vanderspek, R.; Seager, S.; Jenkins, J. M.; Burke, C. J.; Dragomir, D.; Levine, A. M.; Quintana, E. V.; Rodriguez, J. E.; Smith, J. C.; Wohler, B.
Abstract: We report the discovery of TOI 837b and its validation as a transiting planet. We characterize the system using data from the NASA Transiting Exoplanet Survey Satellite mission, the ESA Gaia mission, ground-based photometry from El Sauce and ASTEP400, and spectroscopy from CHIRON, FEROS, and Veloce. We find that TOI 837 is a T = 9.9 mag G0/F9 dwarf in the southern open cluster IC 2602. The star and planet are therefore ${35}_{-5}^{+11}$ million years old. Combining the transit photometry with a prior on the stellar parameters derived from the cluster color-magnitude diagram, we find that the planet has an orbital period of $8.3\,\mathrm{days}$ and is slightly smaller than Jupiter ( ${R}_{{\rm{p}}}={0.77}_{-0.07}^{+0.09}\,{R}_{\mathrm{Jup}}$ ). From radial velocity monitoring, we limit ${M}_{{\rm{p}}}\sin i$ to less than 1.20 M_Jup (3s). The transits either graze or nearly graze the stellar limb. Grazing transits are a cause for concern, as they are often indicative of astrophysical false-positive scenarios. Our follow-up data show that such scenarios are unlikely. Our combined multicolor photometry, high-resolution imaging, and radial velocities rule out hierarchical eclipsing binary scenarios. Background eclipsing binary scenarios, though limited by speckle imaging, remain a 0.2% possibility. TOI 837b is therefore a validated adolescent exoplanet. The planetary nature of the system can be confirmed or refuted through observations of the stellar obliquity and the planetary mass. Such observations may also improve our understanding of how the physical and orbital properties of exoplanets change in time.

ID: 157771
Type: article
Authors: Bouma, L. G.; Winn, J. N.; Ricker, G. R.; Vanderspek, R.; Latham, David W.; Seager, S.; Jenkins, J. M.; Barclay, T.; Collins, Karen A.; Doty, J. P.; Louie, D. R.; Quinn, Samuel N.; Rose, M. E.; Smith, J. C.; Villaseñor, J.; Wohler, B.
Abstract: PTFO 8-8695 (CVSO 30) is a star in the 7-10 million year old Orion OB1a cluster that shows brightness dips that resemble planetary transits. Although strong evidence against the planet hypothesis has been presented, the possibility remains debated in the literature. To obtain further clues, we inspected data from the NASA Transiting Exoplanet Survey Satellite (TESS) and the ESA Gaia mission. The Gaia data suggest that PTFO 8-8695 is a binary: the photometric data show it to be overluminous with respect to members of its kinematic group, and the astrometric data are inconsistent with a single star. The TESS light curve shows two different photometric periods. The variability is dominated by a sinusoidal signal with a period of 11.98 hr, presumably caused by stellar rotation. Also present is a 10.76 hr signal consisting of a not-quite sinusoid interrupted by hour-long dips, the type of signal previously interpreted as planetary transits. The phase of the dips is nearly 180° away from the phase of the originally reported dips. As noted previously, this makes them difficult to explain as planetary transits. Instead, we believe that PTFO 8-8695 is a pair of young and rapidly rotating M dwarfs, one of which shows the same "transient-dipper" behavior that has been seen in at least five other cases. The origin of these transient dips is still unknown but likely involves circumstellar material.

ID: 158644
Type: article
Authors: Brahm, Rafael; Nielsen, Louise D.; Wittenmyer, Robert A.; Wang, Songhu; Rodriguez, Joseph E.; Espinoza, Néstor; Jones, Matías I.; Jordán, Andrés; Henning, Thomas; Hobson, Melissa; Kossakowski, Diana; Rojas, Felipe; Sarkis, Paula; Schlecker, Martin; Trifonov, Trifon; Shahaf, Sahar; Ricker, George; Vanderspek, Roland; Latham, David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Addison, Brett C.; Bakos, Gáspár Á.; Bhatti, Waqas; Bayliss, Daniel; Berlind, Perry; Bieryla, Allyson; Bouchy, Francois; Bowler, Brendan P.; Briceño, César; Brown, Timothy M.; Bryant, Edward M.; Caldwell, Douglas A.; Charbonneau, David; Collins, Karen A.; Davis, Allen B.; Esquerdo, Gilbert A.; Fulton, Benjamin J.; Guerrero, Natalia M.; Henze, Christopher E.; Hogan, Aleisha; Horner, Jonathan; Huang, Chelsea X.; Irwin, Jonathan; Kane, Stephen R.; Kielkopf, John; Mann, Andrew W.; Mazeh, Tsevi; McCormac, James; McCully, Curtis; Mengel, Matthew W.; Mireles, Ismael; Okumura, Jack; Plavchan, Peter; Quinn, Samuel N.; Rabus, Markus; Saesen, Sophie; Schlieder, Joshua E.; Segransan, Damien; Shiao, Bernie; Shporer, Avi; Siverd, Robert J.; Stassun, Keivan G.; Suc, Vincent; Tan, Thiam-Guan; Torres, Pascal; Tinney, Chris G.; Udry, Stephane; Vanzi, Leonardo; Vezie, Michael; Vines, Jose I.; Vuckovic, Maja; Wright, Duncan J.; Yahalomi, Daniel A.; Zapata, Abner; Zhang, Hui; Ziegler, Carl
Abstract: We present the discovery of two new 10 day period giant planets from the Transiting Exoplanet Survey Satellite mission, whose masses were precisely determined using a wide diversity of ground-based facilities. TOI-481 b and TOI-892 b have similar radii (0.99 ± 0.01 ${R}_{{\rm{J}}}$ and 1.07 ± 0.02 ${R}_{{\rm{J}}}$ , respectively), and orbital periods (10.3311 days and 10.6266 days, respectively), but significantly different masses (1.53 ± 0.03 ${M}_{{\rm{J}}}$ versus 0.95 ± 0.07 ${M}_{{\rm{J}}}$ , respectively). Both planets orbit metal-rich stars ( $[\mathrm{Fe}/{\rm{H}}]$ = $+0.26\pm 0.05$ dex and $[\mathrm{Fe}/{\rm{H}}]$ = $+0.24\pm 0.05$ for TOI-481 and TOI-892, respectively) but at different evolutionary stages. TOI-481 is a ${M}_{\star }$ = 1.14 ± 0.02 ${M}_{\odot }$ , ${R}_{\star }$ = 1.66 ± 0.02 ${R}_{\odot }$ G-type star ( ${T}_{\mathrm{eff}}$ = $5735\pm 72$ K), that with an age of 6.7 Gyr, is in the turn-off point of the main sequence. TOI-892 on the other hand, is a F-type dwarf star ( ${T}_{\mathrm{eff}}$ = $6261\pm 80$ K), which has a mass of ${M}_{\star }$ = 1.28 ± 0.03 ${M}_{\odot }$ and a radius of ${R}_{\star }$ = 1.39 ± 0.02 ${R}_{\odot }$ . TOI-481 b and TOI-892 b join the scarcely populated region of transiting gas giants with orbital periods longer than 10 days, which is important to constrain theories of the formation and structure of hot Jupiters.

ID: 157601
Type: article
Authors: Burt, Jennifer A.; Nielsen, Louise D.; Quinn, Samuel N.; Mamajek, Eric E.; Matthews, Elisabeth C.; Zhou, George; Seidel, Julia V.; Huang, Chelsea X.; Lopez, Eric; Soto, Maritza; Otegi, Jon; Stassun, Keivan G.; Kreidberg, Laura; Collins, Karen A.; Eastman, Jason D.; Rodriguez, Joseph E.; Vanderburg, Andrew; Halverson, Samuel P.; Teske, Johanna K.; Wang, Sharon X.; Butler, R. Paul; Bouchy, François; Dumusque, Xavier; Segransen, Damien; Shectman, Stephen A.; Crane, Jeffrey D.; Feng, Fabo; Montet, Benjamin T.; Feinstein, Adina D.; Beletski, Yuri; Flowers, Erin; Günther, Maximilian N.; Daylan, Tansu; Collins, Kevin I.; Conti, Dennis M.; Gan, Tianjun; Jensen, Eric L. N.; Kielkopf, John F.; Tan, Thiam-Guan; Helled, Ravit; Dorn, Caroline; Haldemann, Jonas; Lissauer, Jack J.; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Twicken, Joseph D.; Smith, Jeffrey C.; Tenenbaum, Peter; Cartwright, Scott; Barclay, Thomas; Pepper, Joshua; Esquerdo, Gilbert; Fong, William
Abstract: We report the detection of a transiting hot Neptune exoplanet orbiting TOI-824 (SCR J1448-5735), a nearby (d = 64 pc) K4V star, using data from the Transiting Exoplanet Survey Satellite. The newly discovered planet has a radius R_p = 2.93 ± 0.20 ${R}_{\oplus }$ and an orbital period of 1.393 days. Radial velocity measurements using the Planet Finder Spectrograph and the High Accuracy Radial velocity Planet Searcher spectrograph confirm the existence of the planet, and we estimate its mass to be 18.47 ± 1.84 ${M}_{\oplus }$ . The planet's mean density is ${\rho }_{{\rm{p}}}$ = 4.03 ${}_{-0.78}^{+0.98}$ ${\rm{g}}\,{\mathrm{cm}}^{-3}$ , making it more than twice as dense as Neptune. TOI-824 b's high equilibrium temperature makes the planet likely to have a cloud-free atmosphere, and thus it is an excellent candidate for follow-up atmospheric studies. The detectability of TOI-824 b's atmosphere from both ground and space is promising and could lead to the detailed characterization of the most irradiated small planet at the edge of the hot Neptune desert that has retained its atmosphere to date.

ID: 157619
Type: article
Authors: Carmichael, Theron W.; Quinn, Samuel N.; Mustill, Alexander J.; Huang, Chelsea; Zhou, George; Persson, Carina M.; Nielsen, Louise D.; Collins, Karen A.; Ziegler, Carl; Collins, Kevin I.; Rodriguez, Joseph E.; Shporer, Avi; Brahm, Rafael; Mann, Andrew W.; Bouchy, Francois; Fridlund, Malcolm; Stassun, Keivan G.; Hellier, Coel; Seidel, Julia V.; Stalport, Manu; Udry, Stephane; Pepe, Francesco; Ireland, Michael; Žerjal, Maruša; Briceño, César; Law, Nicholas; Jordán, Andrés; Espinoza, Néstor; Henning, Thomas; Sarkis, Paula; Latham, David W.
Abstract: We report the discovery of two intermediate-mass transiting brown dwarfs (BDs), TOI-569b and TOI-1406b, from NASA's Transiting Exoplanet Survey Satellite mission. TOI-569b has an orbital period of P = 6.55604 ± 0.00016 days, a mass of M_b = 64.1 ± 1.9 ${M}_{{\rm{J}}}$ , and a radius of R_b = 0.75 ± 0.02 ${R}_{{\rm{J}}}$ . Its host star, TOI-569, has a mass of M_⋆ = 1.21 ± 0.05 $\,{M}_{\odot }$ , a radius of R_⋆ = 1.47 ± 0.03 $\,{R}_{\odot }$ , $[\mathrm{Fe}/{\rm{H}}]=+0.29\pm 0.09$ dex, and an effective temperature of T_eff = 5768 ± 110 K. TOI-1406b has an orbital period of P = 10.57415 ± 0.00063 days, a mass of M_b = 46.0 ± 2.7 ${M}_{{\rm{J}}}$ , and a radius of R_b = 0.86 ± 0.03 ${R}_{{\rm{J}}}$ . The host star for this BD has a mass of M_⋆ = 1.18 ± 0.09 $\,{M}_{\odot }$ , a radius of R_⋆ = 1.35 ± 0.03 $\,{R}_{\odot }$ , $[\mathrm{Fe}/{\rm{H}}]=-0.08\pm 0.09$ dex, and an effective temperature of T_eff = 6290 ± 100 K. Both BDs are in circular orbits around their host stars and are older than 3 Gyr based on stellar isochrone models of the stars. TOI-569 is one of two slightly evolved stars known to host a transiting BD (the other being KOI-415). TOI-1406b is one of three known transiting BDs to occupy the mass range of 40-50 ${M}_{{\rm{J}}}$ and one of two to have a circular orbit at a period near 10 days (with the first being KOI-205b). Both BDs have reliable ages from stellar isochrones, in addition to their well-constrained masses and radii, making them particularly valuable as tests for substellar isochrones in the BD mass-radius diagram.

ID: 157584
Type: article
Authors: Cloutier, Ryan; Eastman, Jason D.; Rodriguez, Joseph E.; Astudillo-Defru, Nicola; Bonfils, Xavier; Mortier, Annelies; Watson, Christopher A.; Stalport, Manu; Pinamonti, Matteo; Lienhard, Florian; Harutyunyan, Avet; Damasso, Mario; Latham, David W.; Collins, Karen A.; Massey, Robert; Irwin, Jonathan; Winters, Jennifer G.; Charbonneau, David; Ziegler, Carl; Matthews, Elisabeth; Crossfield, Ian J. M.; Kreidberg, Laura; Quinn, Samuel N.; Ricker, George; Vanderspek, Roland; Seager, Sara; Winn, Joshua; Jenkins, Jon M.; Vezie, Michael; Udry, Stéphane; Twicken, Joseph D.; Tenenbaum, Peter; Sozzetti, Alessandro; Ségransan, Damien; Schlieder, Joshua E.; Sasselov, Dimitar; Santos, Nuno C.; Rice, Ken; Rackham, Benjamin V.; Poretti, Ennio; Piotto, Giampaolo; Phillips, David; Pepe, Francesco; Molinari, Emilio; Mignon, Lucile; Micela, Giuseppina; Melo, Claudio; de Medeiros, José R.; Mayor, Michel; Matson, Rachel A.; Martinez Fiorenzano, Aldo F.; Mann, Andrew W.; Magazzú, Antonio; Lovis, Christophe; López-Morales, Mercedes; Lopez, Eric; Lissauer, Jack J.; Lépine, Sébastien; Law, Nicholas; Kielkopf, John F.; Johnson, John A.; Jensen, Eric L. N.; Howell, Steve B.; Gonzales, Erica; Ghedina, Adriano; Forveille, Thierry; Figueira, Pedro; Dumusque, Xavier; Dressing, Courtney D.; Doyon, René; Díaz, Rodrigo F.; Fabrizio, Luca Di; Delfosse, Xavier; Cosentino, Rosario; Conti, Dennis M.; Collins, Kevin I.; Cameron, Andrew Collier; Ciardi, David; Caldwell, Douglas A.; Burke, Christopher; Buchhave, Lars; Briceño, César; Boyd, Patricia; Bouchy, François; Beichman, Charles; Artigau, Étienne; Almenara, Jose M.
Abstract: We present the confirmation of two new planets transiting the nearby mid-M dwarf LTT 3780 (TIC 36724087, TOI-732, V = 13.07, K_s = 8.204, R_s = 0.374 R_☉, M_s = 0.401 M_☉, d = 22 pc). The two planet candidates are identified in a single Transiting Exoplanet Survey Satellite sector and validated with reconnaissance spectroscopy, ground-based photometric follow-up, and high-resolution imaging. With measured orbital periods of P_b = 0.77, P_c = 12.25 days and sizes r_p,b = 1.33 ± 0.07, r_p,c = 2.30 ± 0.16 R_⊕, the two planets span the radius valley in period-radius space around low-mass stars, thus making the system a laboratory to test competing theories of the emergence of the radius valley in that stellar mass regime. By combining 63 precise radial velocity measurements from the High Accuracy Radial velocity Planet Searcher (HARPS) and HARPS-N, we measure planet masses of ${m}_{p,b}={2.62}_{-0.46}^{+0.48}$ and ${m}_{p,c}={8.6}_{-1.3}^{+1.6}$ M_⊕, which indicates that LTT 3780b has a bulk composition consistent with being Earth-like, while LTT 3780c likely hosts an extended H/He envelope. We show that the recovered planetary masses are consistent with predictions from both photoevaporation and core-powered mass-loss models. The brightness and small size of LTT 3780, along with the measured planetary parameters, render LTT 3780b and c as accessible targets for atmospheric characterization of planets within the same planetary system and spanning the radius valley.

ID: 157582
Type: article
Authors: Dai, Fei; Roy, Arpita; Fulton, Benjamin; Robertson, Paul; Hirsch, Lea; Isaacson, Howard; Albrecht, Simon; Mann, Andrew W.; Kristiansen, Martti H.; Batalha, Natalie M.; Beard, Corey; Behmard, Aida; Chontos, Ashley; Crossfield, Ian J. M.; Dalba, Paul A.; Dressing, Courtney; Giacalone, Steven; Hill, Michelle; Howard, Andrew W.; Huber, Daniel; Kane, Stephen R.; Kosiarek, Molly; Lubin, Jack; Mayo, Andrew; Mocnik, Teo; Akana Murphy, Joseph M.; Petigura, Erik A.; Rosenthal, Lee; Rubenzahl, Ryan A.; Scarsdale, Nicholas; Weiss, Lauren M.; Van Zandt, Judah; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Caldwell, Douglas A.; Charbonneau, David; Daylan, Tansu; Günther, Maximilian N.; Morgan, Edward; Quinn, Samuel N.; Rose, Mark E.; Smith, Jeffrey C.
Abstract: We report the measurement of a spectroscopic transit of TOI-1726c, one of two planets transiting a G-type star with V = 6.9 in the Ursa Major Moving Group (∼400 Myr). With a precise age constraint from cluster membership, TOI-1726 provides a great opportunity to test various obliquity excitation scenarios that operate on different timescales. By modeling the Rossiter-McLaughlin (RM) effect, we derived a sky-projected obliquity of $-{1}_{-32}^{{+35}^\circ} $ . This result rules out a polar/retrograde orbit and is consistent with an aligned orbit for planet c. Considering the previously reported, similarly prograde RM measurement of planet b and the transiting nature of both planets, TOI-1726 tentatively conforms to the overall picture that compact multitransiting planetary systems tend to have coplanar, likely aligned orbits. TOI-1726 is also a great atmospheric target for understanding differential atmospheric loss of sub-Neptune planets (planet b 2.2 R_⊕ and c 2.7 R_⊕ both likely underwent photoevaporation). The coplanar geometry points to a dynamically cold history of the system that simplifies any future modeling of atmospheric escape.

ID: 156961
Type: article
Authors: Dalba, Paul A.; Gupta, Arvind F.; Rodriguez, Joseph E.; Dragomir, Diana; Huang, Chelsea X.; Kane, Stephen R.; Quinn, Samuel N.; Bieryla, Allyson; Esquerdo, Gilbert A.; Fulton, Benjamin J.; Scarsdale, Nicholas; Batalha, Natalie M.; Beard, Corey; Behmard, Aida; Chontos, Ashley; Crossfield, Ian J. M.; Dressing, Courtney D.; Giacalone, Steven; Hill, Michelle L.; Hirsch, Lea A.; Howard, Andrew W.; Huber, Daniel; Isaacson, Howard; Kosiarek, Molly; Lubin, Jack; Mayo, Andrew W.; Mocnik, Teo; Akana Murphy, Joseph M.; Petigura, Erik A.; Robertson, Paul; Rosenthal, Lee J.; Roy, Arpita; Rubenzahl, Ryan A.; Van Zandt, Judah; Weiss, Lauren M.; Knudstrup, Emil; Andersen, Mads F.; Grundahl, Frank; Yao, Xinyu; Pepper, Joshua; Villanueva, Steven, Jr.; Ciardi, David R.; Cloutier, Ryan; Jacobs, Thomas Lee; Kristiansen, Martti H.; LaCourse, Daryll M.; Lendl, Monika; Osborn, Hugh P.; Palle, Enric; Stassun, Keivan G.; Stevens, Daniel J.; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Caldwell, Douglas A.; Daylan, Tansu; Fong, William; Goeke, Robert F.; Rose, Mark E.; Rowden, Pamela; Schlieder, Joshua E.; Smith, Jeffrey C.; Vanderburg, Andrew
Abstract: We report the detection of a Saturn-size exoplanet orbiting HD 332231 (TOI 1456) in light curves from the Transiting Exoplanet Survey Satellite (TESS). HD 332231 -- an F8 dwarf star with a V-band magnitude of 8.56 -- was observed by TESS in Sectors 14 and 15. We detect a single-transit event in the Sector 15 presearch data conditioning (PDC) light curve. We obtain spectroscopic follow-up observations of HD 332231 with the Automated Planet Finder, Keck I, and SONG telescopes. The orbital period we infer from radial velocity (RV) observations leads to the discovery of another transit in Sector 14 that was masked by PDC due to scattered light contamination. A joint analysis of the transit and RV data confirms the planetary nature of HD 332231 b, a Saturn-size ( ${0.867}_{-0.025}^{+0.027}\ {R}_{{\rm{J}}} ), sub-Saturn-mass ( $0.244\pm 0.021\ {M}_{{\rm{J}}} ) exoplanet on a 18.71 day circular orbit. The low surface gravity of HD 332231 b and the relatively low stellar flux it receives make it a compelling target for transmission spectroscopy. Also, the stellar obliquity is likely measurable via the Rossiter-McLaughlin effect, an exciting prospect given the 0.14 au orbital separation of HD 332231 b. The spectroscopic observations do not provide substantial evidence for any additional planets in the HD 332231 system, but continued RV monitoring is needed to further characterize this system. We also predict that the frequency and duration of masked data in the PDC light curves for TESS Sectors 14-16 could hide transits of some exoplanets with orbital periods between 10.5 and 17.5 days.

ID: 158650
Type: article
Authors: Davis, Allen B.; Wang, Songhu; Jones, Matias; Eastman, Jason D.; Günther, Maximilian N.; Stassun, Keivan G.; Addison, Brett C.; Collins, Karen A.; Quinn, Samuel N.; Latham, David W.; Trifonov, Trifon; Shahaf, Sahar; Mazeh, Tsevi; Kane, Stephen R.; Narita, Norio; Wang, Xian-Yu; Tan, Thiam-Guan; Ciardi, David R.; Tokovinin, Andrei; Ziegler, Carl; Tronsgaard, René; Millholland, Sarah; Cruz, Bryndis; Berlind, Perry; Calkins, Michael L.; Esquerdo, Gilbert A.; Collins, Kevin I.; Conti, Dennis M.; Murgas, Felipe; Evans, Phil; Lewin, Pablo; Radford, Don J.; Paredes, Leonardo A.; Henry, Todd J.; Hodari-Sadiki, James; Lund, Michael B.; Christiansen, Jessie L.; Law, Nicholas M.; Mann, Andrew W.; Briceño, César; Parviainen, Hannu; Palle, Enric; Watanabe, Noriharu; Ricker, George R.; Vanderspek, Roland; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Krishnamurthy, Akshata; Batalha, Natalie M.; Burt, Jennifer; Colón, Knicole D.; Dynes, Scott; Caldwell, Douglas A.; Morris, Robert; Henze, Christopher E.; Fischer, Debra A.
Abstract: We report the discovery and confirmation of two new hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS): TOI 564 b and TOI 905 b. The transits of these two planets were initially observed by TESS with orbital periods of 1.651 and 3.739 days, respectively. We conducted follow-up observations of each system from the ground, including photometry in multiple filters, speckle interferometry, and radial velocity measurements. For TOI 564 b, our global fitting revealed a classical hot Jupiter with a mass of ${1.463}_{-0.096}^{+0.10}$ M_J and a radius of ${1.02}_{-0.29}^{+0.71}$ R_J. Also a classical hot Jupiter, TOI 905 b has a mass of ${0.667}_{-0.041}^{+0.042}$ M_J and radius of ${1.171}_{-0.051}^{+0.053}$ R_J. Both planets orbit Sun-like, moderately bright, mid-G dwarf stars with V ˜ 11. While TOI 905 b fully transits its star, we found that TOI 564 b has a very high transit impact parameter of ${0.994}_{-0.049}^{+0.083}$ , making it one of only ˜20 known systems to exhibit a grazing transit and one of the brightest host stars among them. Therefore, TOI 564 b is one of the most attractive systems to search for additional nontransiting, smaller planets by exploiting the sensitivity of grazing transits to small changes in inclination and transit duration over a timescale of several years.

ID: 157602
Type: article
Authors: Gilbert, Emily A.; Barclay, Thomas; Schlieder, Joshua E.; Quintana, Elisa V.; Hord, Benjamin J.; Kostov, Veselin B.; Lopez, Eric D.; Rowe, Jason F.; Hoffman, Kelsey; Walkowicz, Lucianne M.; Silverstein, Michele L.; Rodriguez, Joseph E.; Vanderburg, Andrew; Suissa, Gabrielle; Airapetian, Vladimir S.; Clement, Matthew S.; Raymond, Sean N.; Mann, Andrew W.; Kruse, Ethan; Lissauer, Jack J.; Colón, Knicole D.; Kopparapu, Ravi Kumar; Kreidberg, Laura; Zieba, Sebastian; Collins, Karen A.; Quinn, Samuel N.; Howell, Steve B.; Ziegler, Carl; Vrijmoet, Eliot Halley; Adams, Fred C.; Arney, Giada N.; Boyd, Patricia T.; Brande, Jonathan; Burke, Christopher J.; Cacciapuoti, Luca; Chance, Quadry; Christiansen, Jessie L.; Covone, Giovanni; Daylan, Tansu; Dineen, Danielle; Dressing, Courtney D.; Essack, Zahra; Fauchez, Thomas J.; Galgano, Brianna; Howe, Alex R.; Kaltenegger, Lisa; Kane, Stephen R.; Lam, Christopher; Lee, Eve J.; Lewis, Nikole K.; Logsdon, Sarah E.; Mandell, Avi M.; Monsue, Teresa; Mullally, Fergal; Mullally, Susan E.; Paudel, Rishi R.; Pidhorodetska, Daria; Plavchan, Peter; Reyes, Naylynn Tañón; Rinehart, Stephen A.; Rojas-Ayala, Bárbara; Smith, Jeffrey C.; Stassun, Keivan G.; Tenenbaum, Peter; Vega, Laura D.; Villanueva, Geronimo L.; Wolf, Eric T.; Youngblood, Allison; Ricker, George R.; Vanderspek, Roland K.; Latham, David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Bakos, Gáspár Å.; Briceño, César; Ciardi, David R.; Cloutier, Ryan; Conti, Dennis M.; Couperus, Andrew; Di Sora, Mario; Eisner, Nora L.; Everett, Mark E.; Gan, Tianjun; Hartman, Joel D.; Henry, Todd; Isopi, Giovanni; Jao, Wei-Chun; Jensen, Eric L. N.; Law, Nicholas; Mallia, Franco; Matson, Rachel A.; Shappee, Benjamin J.; Le Wood, Mackennae; Winters, Jennifer G.
Abstract: We present the discovery and validation of a three-planet system orbiting the nearby (31.1 pc) M2 dwarf star TOI-700 (TIC 150428135). TOI-700 lies in the TESS continuous viewing zone in the Southern Ecliptic Hemisphere; observations spanning 11 sectors reveal three planets with radii ranging from 1 R_⊕ to 2.6 R_⊕ and orbital periods ranging from 9.98 to 37.43 days. Ground-based follow-up combined with diagnostic vetting and validation tests enables us to rule out common astrophysical false-positive scenarios and validate the system of planets. The outermost planet, TOI-700 d, has a radius of 1.19 ± 0.11 R_⊕ and resides within a conservative estimate of the host star's habitable zone, where it receives a flux from its star that is approximately 86% of Earth's insolation. In contrast to some other low-mass stars that host Earth-sized planets in their habitable zones, TOI-700 exhibits low levels of stellar activity, presenting a valuable opportunity to study potentially rocky planets over a wide range of conditions affecting atmospheric escape. While atmospheric characterization of TOI-700 d with the James Webb Space Telescope (JWST) will be challenging, the larger sub-Neptune, TOI-700 c (R = 2.63 R_⊕), will be an excellent target for JWST and future space-based observatories. TESS is scheduled to once again observe the Southern Hemisphere, and it will monitor TOI-700 for an additional 11 sectors in its extended mission. These observations should allow further constraints on the known planet parameters and searches for additional planets and transit timing variations in the system.

ID: 155846
Type: article
Authors: Günther, Maximilian N.; Zhan, Zhuchang; Seager, Sara; Rimmer, Paul B.; Ranjan, Sukrit; Stassun, Keivan G.; Oelkers, Ryan J.; Daylan, Tansu; Newton, Elisabeth; Kristiansen, Martti H.; Olah, Katalin; Gillen, Edward; Rappaport, Saul; Ricker, George R.; Vanderspek, Roland K.; Latham, David W.; Winn, Joshua N.; Jenkins, Jon M.; Glidden, Ana; Fausnaugh, Michael; Levine, Alan M.; Dittmann, Jason A.; Quinn, Samuel N.; Krishnamurthy, Akshata; Ting, Eric B.
Abstract: We perform a study of stellar flares for the 24,809 stars observed with 2 minute cadence during the first two months of the TESS mission. Flares may erode exoplanets' atmospheres and impact their habitability, but might also trigger the genesis of life around small stars. TESS provides a new sample of bright dwarf stars in our galactic neighborhood, collecting data for thousands of M dwarfs that might host habitable exoplanets. Here, we use an automated search for flares accompanied by visual inspection. Then, our public allesfitter code robustly selects the appropriate model for potentially complex flares via Bayesian evidence. We identify 1228 flaring stars, 673 of which are M dwarfs. Among 8695 flares in total, the largest superflare increased the stellar brightness by a factor of 16.1. Bolometric flare energies range from 10^31.0 to 10^36.9 erg, with a median of 10^33.1 erg. Furthermore, we study the flare rate and energy as a function of stellar type and rotation period. We solidify past findings that fast rotating M dwarfs are the most likely to flare and that their flare amplitude is independent of the rotation period. Finally, we link our results to criteria for prebiotic chemistry, atmospheric loss through coronal mass ejections, and ozone sterilization. Four of our flaring M dwarfs host exoplanet candidates alerted on by TESS, for which we discuss how these effects can impact life. With upcoming TESS data releases, our flare analysis can be expanded to almost all bright small stars, aiding in defining criteria for exoplanet habitability.

ID: 156380
Type: article
Authors: Huang, Chelsea X.; Quinn, Samuel N.; Vanderburg, Andrew; Becker, Juliette; Rodriguez, Joseph E.; Pozuelos, Francisco J.; Gandolfi, Davide; Zhou, George; Mann, Andrew W.; Collins, Karen A.; Crossfield, Ian; Barkaoui, Khalid; Collins, Kevin I.; Fridlund, Malcolm; Gillon, Michaël; Gonzales, Erica J.; Günther, Maximilian N.; Henry, Todd J.; Howell, Steve B.; James, Hodari-Sadiki; Jao, Wei-Chun; Jehin, Emmanuël; Jensen, Eric L. N.; Kane, Stephen R.; Lissauer, Jack J.; Matthews, Elisabeth; Matson, Rachel A.; Paredes, Leonardo A.; Schlieder, Joshua E.; Stassun, Keivan G.; Shporer, Avi; Sha, Lizhou; Tan, Thiam-Guan; Georgieva, Iskra; Mathur, Savita; Palle, Enric; Persson, Carina M.; Eylen, Vincent Van; Ricker, George R.; Vanderspek, Roland K.; Latham, David W.; Winn, Joshua N.; Seager, S.; Jenkins, Jon M.; Burke, Christopher J.; Goeke, Robert F.; Rinehart, Stephen; Rose, Mark E.; Ting, Eric B.; Torres, Guillermo; Wong, Ian
Abstract: Hot Jupiters are rarely accompanied by other planets within a factor of a few in orbital distance. Previously, only two such systems have been found. Here, we report the discovery of a third system using data from the Transiting Exoplanet Survey Satellite (TESS). The host star, TOI-1130, is an eleventh magnitude K-dwarf in Gaia G-band. It has two transiting planets: a Neptune-sized planet (3.65 ± 0.10 R_\oplus) with a 4.1 days period, and a hot Jupiter (1.50_-0.22^+0.27 R_J) with an 8.4 days period. Precise radial-velocity observations show that the mass of the hot Jupiter is 0.974_-0.044^+0.043 M_J. For the inner Neptune, the data provide only an upper limit on the mass of 0.17 M_J (3σ). Nevertheless, we are confident that the inner planet is real, based on follow-up ground-based photometry and adaptive-optics imaging that rule out other plausible sources of the TESS transit signal. The unusual planetary architecture of and the brightness of the host star make TOI-1130 a good test case for planet formation theories, and an attractive target for future spectroscopic observations.