Publication Search Results

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: 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: 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: 158638
Type: article
Authors: Stevens, Daniel J.; Zhou, George; Johnson, Marshall C.; Rizzuto, Aaron C.; Rodriguez, Joseph E.; Bieryla, Allyson; Collins, Karen A.; Villanueva, Steven, Jr.; Wright, Jason T.; Gaudi, B. Scott; Latham, David W.; Beatty, Thomas G.; Lund, Michael B.; Siverd, Robert J.; Kraus, Adam L.; Wachiraphan, Patcharapol; Berlind, Perry; Calkins, Michael L.; Esquerdo, Gilbert A.; Kielkopf, John F.; Kuhn, Rudolf B.; Manner, Mark; Pepper, Joshua; Stassun, Keivan G.
Abstract: We present the discovery of KELT J072709 + 072007 (HD 58730), a very low mass ratio (q = M₂/M₁ ? 0.07) eclipsing binary (EB) identified by the Kilodegree Extremely Little Telescope (KELT) survey. We present the discovery light curve and perform a global analysis of four high-precision ground-based light curves, the Transiting Exoplanets Survey Satellite (TESS) light curve, radial velocity (RV) measurements, Doppler Tomography (DT) measurements, and the broad-band spectral energy distribution. Results from the global analysis are consistent with a fully convective ( $M_2 = 0.22 \pm 0.02\ \, \mathrm{M}_{\odot })$ M star transiting a late-B primary ( $M_1 = 3.34^{+0.07}_{-0.09}\ \, \mathrm{M}_{\odot }\,\mathrm{ and}\,\ T_{\rm eff,1} = 11960^{+430}_{-520}\ {\rm K}$ ). We infer that the primary star is $183_{-30}^{+33}$ Myr old and that the companion star's radius is inflated by $26 \pm 8{{\ \rm per\ cent}}$ relative to the predicted value from a low-mass isochrone of similar age. We separately and analytically fit for the variability in the out-of-eclipse TESS phase curve, finding good agreement between the resulting stellar parameters and those from the global fit. Such systems are valuable for testing theories of binary star formation and understanding how the environment of a star in a close-but-detached binary affects its physical properties. In particular, we examine how a star's properties in such a binary might differ from the properties it would have in isolation.

ID: 157123
Type: article
Authors: Šubjak, Ján; Sharma, Rishikesh; Carmichael, Theron W.; Johnson, Marshall C.; Gonzales, Erica J.; Matthews, Elisabeth; Boffin, Henri M. J.; Brahm, Rafael; Chaturvedi, Priyanka; Chakraborty, Abhijit; Ciardi, David R.; Collins, Karen A.; Esposito, Massimiliano; Fridlund, Malcolm; Gan, Tianjun; Gandolfi, Davide; García, Rafael A.; Guenther, Eike; Hatzes, Artie; Latham, David W.; Mathis, Stéphane; Mathur, Savita; Persson, Carina M.; Relles, Howard M.; Schlieder, Joshua E.; Barclay, Thomas; Dressing, Courtney D.; Crossfield, Ian; Howard, Andrew W.; Rodler, Florian; Zhou, George; Quinn, Samuel N.; Esquerdo, Gilbert A.; Calkins, Michael L.; Berlind, Perry; Stassun, Keivan G.; Blažek, Martin; Skarka, Marek; Špoková, Magdalena; Žák, Jiří; Albrecht, Simon; Sobrino, Roi Alonso; Beck, Paul; Cabrera, Juan; Carleo, Ilaria; Cochran, William D.; Csizmadia, Szilard; Dai, Fei; Deeg, Hans J.; de Leon, Jerome P.; Eigmüller, Philipp; Endl, Michael; Erikson, Anders; Fukui, Akihiko; Georgieva, Iskra; González-Cuesta, Lucía; Grziwa, Sascha; Hidalgo, Diego; Hirano, Teruyuki; Hjorth, Maria; Knudstrup, Emil; Korth, Judith; Lam, Kristine W. F.; Livingston, John H.; Lund, Mikkel N.; Luque, Rafael; Rodríguez, Pilar Montanes; Murgas, Felipe; Narita, Norio; Nespral, David; Niraula, Prajwal; Nowak, Grzegorz; Pallé, Enric; Pätzold, Martin; Prieto-Arranz, Jorge; Rauer, Heike; Redfield, Seth; Ribas, Ignasi; Smith, Alexis M. S.; Eylen, Vincent Van; Kabáth, Petr
Abstract: We report the discovery of an intermediate-mass transiting brown dwarf (BD), TOI-503b, from the TESS mission. TOI-503b is the first BD discovered by TESS, and it has circular orbit around a metallic-line A-type star with a period of P = 3.6772 ± 0.0001 days. The light curve from TESS indicates that TOI-503b transits its host star in a grazing manner, which limits the precision with which we measure the BD's radius ( ${R}_{b}={1.34}_{-0.15}^{+0.26}{R}_{{\rm{J}}} ). We obtained high- resolution spectroscopic observations with the FIES, Ondřejov, PARAS, Tautenburg, and TRES spectrographs, and measured the mass of TOI-503b to be M_b = 53.7 ± 1.2 ${M}_{{\rm{J}}} . The host star has a mass of M_⋆ = 1.80 ± 0.06 M_☉, a radius of R_⋆ = 1.70 ± 0.05R_☉, an effective temperature of T_eff = 7650 ± 160 K, and a relatively high metallicity of 0.61 ± 0.07 dex. We used stellar isochrones to derive the age of the system to be ∼180 Myr, which places its age between that of RIK 72b (a ∼10 Myr old BD in the Upper Scorpius stellar association) and AD 3116b (a ∼600 Myr old BD in the Praesepe cluster). Given the difficulty in measuring the tidal interactions between BDs and their host stars, we cannot precisely say whether this BD formed in situ or has had its orbit circularized by its host star over the relatively short age of the system. Instead, we offer an examination of plausible values for the tidal quality factor for the star and BD. TOI-503b joins a growing number of known short-period, intermediate-mass BDs orbiting main-sequence stars, and is the second such BD known to transit an A star, after HATS-70b. With the growth in the population in this regime, the driest region in the BD desert ( $35\mbox{--}55{M}_{{\rm{J}}}\sin i ) is reforesting.

ID: 156878
Type: article
Authors: Winters, Jennifer G.; Irwin, Jonathan M.; Charbonneau, David; Latham, David W.; Medina, Amber M.; Mink, Jessica; Esquerdo, Gilbert A.; Berlind, Perry; Calkins, Michael L.; Berta-Thompson, Zachory K.
Abstract: We present the spectroscopic orbits of 11 nearby, mid-to-late M dwarf binary systems in a variety of configurations: 2 single-lined binaries (SB1s), 7 double-lined binaries (SB2s), 1 double-lined triple (ST2), and 1 triple-lined triple (ST3). Eight of these orbits are the first published for these systems, while five are newly identified multiples. We obtained multi-epoch, high-resolution spectra with the TRES instrument on the 1.5 m Tillinghast Reflector at the Fred Lawrence Whipple Observatory located on Mt. Hopkins in AZ. Using the TiO molecular bands at 7065-7165 Å, we calculated radial velocities for these systems, from which we derived their orbits. We find LHS 1817 to have in a 7 hr period a companion that is likely a white dwarf, due to the ellipsoidal modulation we see in our MEarth-North light-curve data. We find G 123-45 and LTT 11586 to host companions with minimum masses of 41 M_Jup and 44 M_Jup with orbital periods of 35 and 15 days, respectively. We find 2MA 0930+0227 to have a rapidly rotating stellar companion in a 917 day orbital period. GJ 268, GJ 1029, LP 734-34, GJ 1182, G 258-17, and LTT 7077are SB2s with stellar companions with orbital periods of 10, 96, 34, 154, 5, and 84 days; LP 655-43 is an ST3 with one companion in an 18 day orbital period and an outer component in a longer undetermined period. In addition, we present radial velocities for both components of L 870-44AB and for the outer components of LTT 11586 and LP 655-43.

ID: 154407
Type: article
Authors: Conroy, Charlie; Bonaca, Ana; Cargile, Phillip; Johnson, Benjamin D.; Caldwell, Nelson; Naidu, Rohan P.; Zaritsky, Dennis; Fabricant, Daniel; Moran, Sean; Rhee, Jaehyon; Szentgyorgyi, Andrew; Berlind, Perry; Calkins, Michael L.; Kattner, ShiAnne; Ly, Chun
Abstract: Modern theories of galaxy formation predict that the Galactic stellar halo was hierarchically assembled from the accretion and disruption of smaller systems. This hierarchical assembly is expected to produce a high degree of structure in the combined phase and chemistry space; this structure should provide a relatively direct probe of the accretion history of our Galaxy. Revealing this structure requires precise 3D positions (including distances), 3D velocities, and chemistry for large samples of stars. The Gaia satellite is delivering proper motions and parallaxes for >1 billion stars to G ≈ 20. However, radial velocities and metallicities will only be available to G ≈ 15, which is insufficient to probe the outer stellar halo (≳10 kpc). Moreover, parallaxes will not be precise enough to deliver high-quality distances for stars beyond ̃10 kpc. Identifying accreted systems throughout the stellar halo therefore requires a large ground-based spectroscopic survey to complement Gaia. Here we provide an overview of the H3 Stellar Spectroscopic Survey, which will deliver precise stellar parameters and spectrophotometric distances for ≈200,000 stars to r = 18. Spectra are obtained with the Hectochelle instrument at the MMT, which is configured for the H3 Survey to deliver resolution R ≈ 23,000 spectra covering the wavelength range 5150-5300 Å. The survey is optimized for stellar halo science and therefore focuses on high Galactic latitude fields (| b| > 30^\circ ), sparsely sampling 15,000 sq. degrees. Targets are selected on the basis of Gaia parallaxes, enabling very efficient selection of bona fide halo stars. The survey began in the fall of 2017 and has collected 88,000 spectra to-date. All of the data, including the derived stellar parameters, will eventually be made publicly available via the survey website: h3s urvey.rc.fas.harvard.edu.

ID: 151839
Type: article
Authors: Dattilo, Anne; Vanderburg, Andrew; Shallue, Christopher J.; Mayo, Andrew W.; Berlind, Perry; Bieryla, Allyson; Calkins, Michael L.; Esquerdo, Gilbert A.; Everett, Mark E.; Howell, Steve B.; Latham, David W.; Scott, Nicholas J.; Yu, Liang
Abstract: For years, scientists have used data from NASA’s Kepler Space Telescope to look for and discover thousands of transiting exoplanets. In its extended K2 mission, Kepler observed stars in various regions of the sky all across the ecliptic plane, and therefore in different galactic environments. Astronomers want to learn how the populations of exoplanets are different in these different environments. However, this requires an automatic and unbiased way to identify exoplanets in these regions and rule out false-positive signals that mimic transiting planet signals. We present a method for classifying these exoplanet signals using deep learning, a class of machine learning algorithms that have become popular in fields ranging from medical science to linguistics. We modified a neural network previously used to identify exoplanets in the Kepler field to be able to identify exoplanets in different K2 campaigns that exist in a range of galactic environments. We train a convolutional neural network, called AstroNet- K2, to predict whether a given possible exoplanet signal is really caused by an exoplanet or a false positive. AstroNet- K2 is highly successful at classifying exoplanets and false positives, with accuracy of 98% on our test set. It is especially efficient at identifying and culling false positives, but for now, it still needs human supervision to create a complete and reliable planet candidate sample. We use AstroNet- K2 to identify and validate two previously unknown exoplanets. Our method is a step toward automatically identifying new exoplanets in K2 data and learning how exoplanet populations depend on their galactic birthplace.

ID: 155119
Type: article
Authors: Hosseinzadeh, Griffin; Cowperthwaite, P. S.; Gomez, Sebastian; Villar, Victoria Ashley; Nicholl, M.; Margutti, R.; Berger, Edo; Chornock, R.; Paterson, K.; Fong, W.; Savchenko, V.; Short, P.; Alexander, K. D.; Blanchard, Peter K.; Braga, J.; Calkins, Michael L.; Cartier, R.; Coppejans, D. L.; Eftekhari, Tarraneh; Laskar, T.; Ly, C.; Patton, Locke; Pelisoli, I.; Reichart, D. E.; Terreran, G.; Williams, Peter K. G.
Abstract: On 2019 April 25.346 and 26.640 UT the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo gravitational-wave (GW) observatory announced the detection of the first candidate events in Observing Run 3 that contained at least one neutron star (NS). S190425z is a likely binary neutron star (BNS) merger at d _L = 156 ± 41 Mpc, while S190426c is possibly the first NS-black hole (BH) merger ever detected, at d _L = 377 ± 100 Mpc, although with marginal statistical significance. Here we report our optical follow-up observations for both events using the MMT 6.5 m telescope, as well as our spectroscopic follow-up of candidate counterparts (which turned out to be unrelated) with the 4.1 m SOAR telescope. We compare to publicly reported searches, explore the overall areal coverage and depth, and evaluate those in relation to the optical/near-infrared (NIR) kilonova emission from the BNS merger GW170817, to theoretical kilonova models, and to short gamma-ray burst (SGRB) afterglows. We find that for a GW170817-like kilonova, the partial volume covered spans up to about 40% for S190425z and 60% for S190426c. For an on-axis jet typical of SGRBs, the search effective volume is larger, but such a configuration is expected in at most a few percent of mergers. We further find that wide- field γ-ray and X-ray limits rule out luminous on-axis SGRBs, for a large fraction of the localization regions, although these searches are not sufficiently deep in the context of the γ-ray emission from GW170817 or off-axis SGRB afterglows. The results indicate that some optical follow-up searches are sufficiently deep for counterpart identification to about 300 Mpc, but that localizations better than 1000 deg² are likely essential.

ID: 150442
Type: article
Authors: Labadie-Bartz, Jonathan; Rodriguez, Joseph E.; Stassun, Keivan G.; Ciardi, David R.; Penev, Kaloyan; Johnson, Marshall C.; Gaudi, B. Scott; Colón, Knicole D.; Bieryla, Allyson; Latham, David W.; Pepper, Joshua; Collins, Karen A.; Evans, Phil; Relles, Howard; Siverd, Robert J.; Bento, Joao; Yao, Xinyu; Stockdale, Chris; Tan, Thiam-Guan; Zhou, George; Eastman, Jason D.; Albrow, Michael D.; Bayliss, Daniel; Beatty, Thomas G.; Berlind, Perry; Bozza, Valerio; Calkins, Michael L.; Cohen, David H.; Curtis, Ivan A.; Esquerdo, Gilbert A.; Feliz, Dax; Fulton, Benjamin J.; Gregorio, Joao; James, David; Jensen, Eric L. N.; Johnson, John Asher; Johnson, Samson A.; Joner, Michael D.; Kasper, David; Kielkopf, John F.; Kuhn, Rudolf B.; Lund, Michael B.; Malpas, Amber; Manner, Mark; McCrady, Nate; McLeod, Kim K.; Oberst, Thomas E.; Penny, Matthew T.; Reed, Phillip A.; Sliski, David H.; Stephens, Denise C.; Stevens, Daniel J.; Villanueva, Steven, Jr.; Wittenmyer, Robert A.; Wright, J. T.; Zambelli, Roberto
Abstract: We present the discovery of KELT-22Ab, a hot Jupiter from the KELT-South survey. KELT-22Ab transits the moderately bright (V ∼ 11.1) Sun-like G2V star TYC 7518-468-1. The planet has an orbital period of P =1.3866529+/- 0.0000027 days, a radius of {R}_P={1.285}_-0.071^+0.12 {R}_J, and a relatively large mass of {M}_P={3.47}_-0.14^+0.15 {M}_J. The star has {R}_\star ={1.099}_-0.046^+0.079 {R}_ȯ , {M}_\star ={1.092}_-0.041^+0.045 {M}_ȯ , {T}_eff} ={5767}_-49⁺⁵⁰ K, {log}{g}_\star ={4.393}_-0.060^+0.039 (cgs), and [m/H] = +{0.259}_-0.083^+0.085; thus other than its slightly super-solar metallicity, it appears to be a near-solar twin. Surprisingly, KELT-22A exhibits kinematics and a Galactic orbit that are somewhat atypical for thin-disk stars. Nevertheless, the star is rotating rapidly for its estimated age, and shows evidence of chromospheric activity. Imaging reveals a slightly fainter companion to KELT-22A that is likely bound, with a projected separation of 6″ (∼1400 au). In addition to the orbital motion caused by the transiting planet, we detect a possible linear trend in the radial velocity of KELT-22A, suggesting the presence of another relatively nearby body that is perhaps non-stellar. KELT-22Ab is highly irradiated (as a consequence of the small semimajor axis of a/{R}_\star =4.97), and is mildly inflated. At such small separations, tidal forces become significant. The configuration of this system is optimal for measuring the rate of tidal dissipation within the host star. Our models predict that, due to tidal forces, the semimajor axis is decreasing rapidly, and KELT-22Ab is predicted to spiral into the star within the next Gyr.

ID: 154287
Type: article
Authors: Rampalli, Rayna; Vanderburg, Andrew; Bieryla, Allyson; Latham, David W.; Quinn, Samuel N.; Baranec, Christoph; Berlind, Perry; Calkins, Michael L.; Cochran, William D.; Duev, Dmitry A.; Endl, Michael; Esquerdo, Gilbert A.; Jensen-Clem, Rebecca; Law, Nicholas M.; Mayo, Andrew W.; Riddle, Reed; Salama, Maïssa
Abstract: We report on the discovery of a hot Saturn-sized planet (9.916 ± 0.985 R _⊕) around a late F-star, K2-308, observed in Campaign 13 of the K2 mission. We began studying this planet candidate because prior to the release of Gaia DR2, the host star was thought to have been a member (≥slant 90 % membership probability) of the ≈ 1 {Gyr} open cluster NGC 1817 based on its kinematics and photometric distance. We identify the host star (among three stars within the K2 photometric aperture) using seeing-limited photometry and rule out false-positive scenarios using adaptive optics imaging and radial velocity observations. We statistically validate K2-308b by calculating a false-positive probability rate of 0.01 % . However, we also show using new kinematic measurements provided by Gaia DR2 and our measured radial velocity of the system that K2-308 is unassociated with the cluster NGC 1817. Therefore, the long running search for a giant transiting planet in an open cluster remains fruitless. Finally, we note that our use of seeing-limited photometry is a good demonstration of similar techniques that are already being used to follow up Transiting Exoplanet Survey Satellite (TESS) planet candidates, especially in crowded regions.

ID: 154595
Type: article
Authors: Rodriguez, Joseph E.; Eastman, Jason D.; Zhou, George; Quinn, Samuel N.; Beatty, Thomas G.; Penev, Kaloyan; Johnson, Marshall C.; Cargile, Phillip A.; Latham, David W.; Bieryla, Allyson; Collins, Karen A.; Dressing, Courtney D.; Ciardi, David R.; Relles, Howard M.; Murawski, Gabriel; Nishiumi, Taku; Yonehara, Atsunori; Ishimaru, Ryo; Yoshida, Fumi; Gregorio, Joao; Lund, Michael B.; Stevens, Daniel J.; Stassun, Keivan G.; Gaudi, B. Scott; Colón, Knicole D.; Pepper, Joshua; Narita, Norio; Awiphan, Supachai; Chuanraksasat, Pongpichit; Benni, Paul; Zambelli, Roberto; Garrison, Lehman H.; Wilson, Maurice L.; Cornachione, Matthew A.; Wang, Sharon X.; Labadie-Bartz, Jonathan; Rodríguez, Romy; Siverd, Robert J.; Yao, Xinyu; Bayliss, Daniel; Berlind, Perry; Calkins, Michael L.; Christiansen, Jessie L.; Cohen, David H.; Conti, Dennis M.; Curtis, Ivan A.; DePoy, D. L.; Esquerdo, Gilbert A.; Evans, Phil; Feliz, Dax; Fulton, Benjamin J.; Holoien, Thomas W. -S; James, David J.; Jayasinghe, Tharindu; Jang-Condell, Hannah; Jensen, Eric L. N.; Johnson, John A.; Joner, Michael D.; Khakpash, Somayeh; Kielkopf, John F.; Kuhn, Rudolf B.; Manner, Mark; Marshall, Jennifer L.; McLeod, Kim K.; McCrady, Nate; Oberst, Thomas E.; Oelkers, Ryan J.; Penny, Matthew T.; Reed, Phillip A.; Sliski, David H.; Shappee, B. J.; Stephens, Denise C.; Stockdale, Chris; Tan, Thiam-Guan; Trueblood, Mark; Trueblood, Pat; Villanueva, Steven, Jr.; Wittenmyer, Robert A.; Wright, Jason T.
Abstract: We present the discovery of KELT-24 b, a massive hot Jupiter orbiting a bright (V = 8.3 mag, K = 7.2 mag) young F-star with a period of 5.6 days. The host star, KELT-24 (HD 93148), has a T _eff = {6509}_-49⁺⁵⁰ K, a mass of M _* = {1.460}_-0.059^+0.055 M _☉, a radius of R _* = 1.506 ± 0.022 R _☉, and an age of {0.78}_-0.42^+0.61 Gyr. Its planetary companion (KELT-24 b) has a radius of R _P = 1.272 ± 0.021 R _J and a mass of M _P = {5.18}_-0.22^+0.21 M _J, and from Doppler tomographic observations, we find that the planet's orbit is well- aligned to its host star's projected spin axis (λ ={2.6}_-3.6^+5.1). The young age estimated for KELT-24 suggests that it only recently started to evolve from the zero- age main sequence. KELT-24 is the brightest star known to host a transiting giant planet with a period between 5 and 10 days. Although the circularization timescale is much longer than the age of the system, we do not detect a large eccentricity or significant misalignment that is expected from dynamical migration. The brightness of its host star and its moderate surface gravity make KELT-24b an intriguing target for detailed atmospheric characterization through spectroscopic emission measurements since it would bridge the current literature results that have primarily focused on lower mass hot Jupiters and a few brown dwarfs.

ID: 151870
Type: article
Authors: Rodriguez, Joseph E.; Quinn, Samuel N.; Huang, Chelsea X.; Vanderburg, Andrew; Penev, Kaloyan; Brahm, Rafael; Jordán, Andrés; Ikwut-Ukwa, Mma; Tsirulik, Shelly; Latham, David W.; Stassun, Keivan G.; Shporer, Avi; Ziegler, Carl; Matthews, Elisabeth; Eastman, Jason D.; Gaudi, B. Scott; Collins, Karen A.; Guerrero, Natalia; Relles, Howard M.; Barclay, Thomas; Batalha, Natalie M.; Berlind, Perry; Bieryla, Allyson; Bouma, L. G.; Boyd, Patricia T.; Burt, Jennifer; Calkins, Michael L.; Christiansen, Jessie; Ciardi, David R.; Colón, Knicole D.; Conti, Dennis M.; Crossfield, Ian J. M.; Daylan, Tansu; Dittmann, Jason; Dragomir, Diana; Dynes, Scott; Espinoza, Néstor; Esquerdo, Gilbert A.; Essack, Zahra; Garcia Soto, Aylin; Glidden, Ana; Günther, Maximilian N.; Henning, Thomas; Jenkins, Jon M.; Kielkopf, John F.; Krishnamurthy, Akshata; Law, Nicholas M.; Levine, Alan M.; Lewin, Pablo; Mann, Andrew W.; Morgan, Edward H.; Morris, Robert L.; Oelkers, Ryan J.; Paegert, Martin; Pepper, Joshua; Quintana, Elisa V.; Ricker, George R.; Rowden, Pamela; Seager, Sara; Sarkis, Paula; Schlieder, Joshua E.; Sha, Lizhou; Tokovinin, Andrei; Torres, Guillermo; Vanderspek, Roland K.; Villanueva, Steven, Jr.; Villaseñor, Jesus Noel; Winn, Joshua N.; Wohler, Bill; Wong, Ian; Yahalomi, Daniel A.; Yu, Liang; Zhan, Zhuchang; Zhou, George
Abstract: We report the discovery of TOI-172 b from the Transiting Exoplanet Survey Satellite (TESS) mission, a massive hot Jupiter transiting a slightly evolved G star with a 9.48-day orbital period. This is the first planet to be confirmed from analysis of only the TESS full frame images, because the host star was not chosen as a two-minute cadence target. From a global analysis of the TESS photometry and follow-up observations carried out by the TESS Follow-up Observing Program Working Group, TOI-172 (TIC 29857954) is a slightly evolved star with an effective temperature of T _eff = 5645 ± 50 K, a mass of M _⋆ = {1.128}_-0.061^+0.065 M _⊙, radius of R _⋆ = {1.777}_-0.044^+0.047 R _⊙, a surface gravity of log g _⋆ = {3.993}_-0.028^+0.027, and an age of {7.4}_-1.5^+1.6 {Gyr}. Its planetary companion (TOI-172 b) has a radius of R _P = {0.965}_-0.029^+0.032 R _J, a mass of M _P = {5.42}_-0.20^+0.22 M _J, and is on an eccentric orbit (e={0.3806}_-0.0090^+0.0093). TOI-172 b is one of the few known massive giant planets on a highly eccentric short-period orbit. Future study of the atmosphere of this planet and its system architecture offer opportunities to understand the formation and evolution of similar systems.

ID: 154593
Type: article
Authors: Thompson, Todd A.; Kochanek, Christopher S.; Stanek, Krzysztof Z.; Badenes, Carles; Post, Richard S.; Jayasinghe, Tharindu; Latham, David W.; Bieryla, Allyson; Esquerdo, Gilbert A.; Berlind, Perry; Calkins, Michael L.; Tayar, Jamie; Lindegren, Lennart; Johnson, Jennifer A.; Holoien, Thomas W. -S; Auchettl, Katie; Covey, Kevin
Abstract: Black hole binary systems with companion stars are typically found via their x-ray emission, generated by interaction and accretion. Noninteracting binaries are expected to be plentiful in the Galaxy but must be observed using other methods. We combine radial velocity and photometric variability data to show that the bright, rapidly rotating giant star 2MASS J05215658+4359220 is in a binary system with a massive unseen companion. The system has an orbital period of ~83 days and near- zero eccentricity. The photometric variability period of the giant is consistent with the orbital period, indicating star spots and tidal synchronization. Constraints on the giant's mass and radius imply that the unseen companion is 3.3−0.7+2.8 solar masses, indicating that it is a noninteracting low-mass black hole or an unexpectedly massive neutron star.

ID: 154440
Type: article
Authors: Wilson, Maurice L.; Eastman, Jason D.; Cornachione, Matthew A.; Wang, Sharon X.; Johnson, Samson A.; Sliski, David H.; Schap, William J.,III; Morton, Timothy D.; Johnson, John Asher; McCrady, Nate; Wright, Jason T.; Wittenmyer, Robert A.; Plavchan, Peter; Blake, Cullen H.; Swift, Jonathan J.; Bottom, Michael; Baker, Ashley D.; Barnes, Stuart I.; Berlind, Perry; Blackhurst, Eric; Beatty, Thomas G.; Bolton, Adam S.; Cale, Bryson; Calkins, Michael L.; Colón, Ana; de Vera, Jon; Esquerdo, Gilbert; Falco, Emilio E.; Fortin, Pascal; Garcia-Mejia, Juliana; Geneser, Claire; Gibson, Steven R.; Grell, Gabriel; Groner, Ted; Halverson, Samuel; Hamlin, John; Henderson, M.; Horner, J.; Houghton, Audrey; Janssens, Stefaan; Jonas, Graeme; Jones, Damien; Kirby, Annie; Lawrence, George; Luebbers, Julien Andrew; Muirhead, Philip S.; Myles, Justin; Nava, Chantanelle; Rivera-García, Kevin O.; Reed, Tony; Relles, Howard M.; Riddle, Reed; Robinson, Connor; Chaput de Saintonge, Forest; Sergi, Anthony
Abstract: The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7 m robotic telescopes fiber-fed to a KiwiSpec spectrograph. The MINERVA mission is to discover super-Earths in the habitable zones of nearby stars. This can be accomplished with MINERVA's unique combination of high precision and high cadence over long time periods. In this work, we detail changes to the MINERVA facility that have occurred since our previous paper. We then describe MINERVA's robotic control software, the process by which we perform 1D spectral extraction, and our forward modeling Doppler pipeline. In the process of improving our forward modeling procedure, we found that our spectrograph's intrinsic instrumental profile is stable for at least nine months. Because of that, we characterized our instrumental profile with a time-independent, cubic spline function based on the profile in the cross dispersion direction, with which we achieved a radial velocity precision similar to using a conventional "sum-of-Gaussians" instrumental profile: 1.8 m s^-1 over 1.5 months on the RV standard star HD 122064. Therefore, we conclude that the instrumental profile need not be perfectly accurate as long as it is stable. In addition, we observed 51 Peg and our results are consistent with the literature, confirming our spectrograph and Doppler pipeline are producing accurate and precise radial velocities.

ID: 154718
Type: article
Authors: Zhou, George; Huang, C. X.; Bakos, G. Á.; Hartman, J. D.; Latham, David W.; Quinn, Samuel N.; Collins, Karen A.; Winn, J. N.; Wong, I.; Kovács, G.; Csubry, Z.; Bhatti, W.; Penev, K.; Bieryla, Allyson; Esquerdo, Gilbert A.; Berlind, Perry; Calkins, Michael L.; de Val-Borro, M.; Noyes, R. W.; Lázár, J.; Papp, I.; Sári, P.; Kovács, T.; Buchhave, Lars A.; Szklenar, T.; Béky, B.; Johnson, M. C.; Cochran, W. D.; Kniazev, A. Y.; Stassun, K. G.; Fulton, B. J.; Shporer, A.; Espinoza, N.; Bayliss, D.; Everett, M.; Howell, S. B.; Hellier, C.; Anderson, D. R.; Collier Cameron, A.; West, R. G.; Brown, D. J. A.; Schanche, N.; Barkaoui, K.; Pozuelos, F.; Gillon, M.; Jehin, E.; Benkhaldoun, Z.; Daassou, A.; Ricker, G.; Vanderspek, R.; Seager, S.; Jenkins, J. M.; Lissauer, Jack J.; Armstrong, J. D.; Collins, K. I.; Gan, T.; Hart, R.; Horne, K.; Kielkopf, J. F.; Nielsen, L. D.; Nishiumi, T.; Narita, N.; Palle, E.; Relles, Howard M.; Sefako, R.; Tan, T. G.; Davies, M.; Goeke, Robert F.; Guerrero, N.; Haworth, K.; Villanueva, S.
Abstract: Wide-field surveys for transiting planets are well suited to searching diverse stellar populations, enabling a better understanding of the link between the properties of planets and their parent stars. We report the discovery of HAT-P-69 b (TOI 625.01) and HAT-P-70 b (TOI 624.01), two new hot Jupiters around A stars from the Hungarian-made Automated Telescope Network (HATNet) survey that have also been observed by the Transiting Exoplanet Survey Satellite. HAT-P-69 b has a mass of {3.58}_-0.58^+0.58 M _Jup and a radius of {1.676}_-0.033^+0.051 R _Jup and resides in a prograde 4.79 day orbit. HAT-P-70 b has a radius of {1.87}_-0.10^+0.15 R _Jup and a mass constraint of and a mass constraint of _Jup and resides in a retrograde 2.74 day orbit. We use the confirmation of these planets around relatively massive stars as an opportunity to explore the occurrence rate of hot Jupiters as a function of stellar mass. We define a sample of 47,126 main-sequence stars brighter than T _mag = 10 that yields 31 giant planet candidates, including 18 confirmed planets, 3 candidates, and 10 false positives. We find a net hot Jupiter occurrence rate of 0.41 ± 0.10% within this sample, consistent with the rate measured by Kepler for FGK stars. When divided into stellar mass bins, we find the occurrence rate to be 0.71 ± 0.31% for G stars, 0.43 ± 0.15% for F stars, and 0.26 ± 0.11% for A stars. Thus, at this point, we cannot discern any statistically significant trend in the occurrence of hot Jupiters with stellar mass. Based on observations obtained with the Hungarian-made Automated Telescope Network. Based in part on observations obtained with the Tillinghast Reflector 1.5 m telescope and the 1.2 m telescope, both operated by the Smithsonian Astrophysical Observatory at the Fred Lawrence Whipple Observatory in Arizona. This work makes use of the Smithsonian Institution High Performance Cluster (SI/HPC). Based in part on observations made with the Southern African Large Telescope (SALT).

ID: 150052
Type: article
Authors: Collins, Karen A.; Collins, Kevin I.; Pepper, Joshua; Labadie-Bartz, Jonathan; Stassun, Keivan G.; Gaudi, B. Scott; Bayliss, Daniel; Bento, Joao; Colón, Knicole D.; Feliz, Dax; James, David; Johnson, Marshall C.; Kuhn, Rudolf B.; Lund, Michael B.; Penny, Matthew T.; Rodriguez, Joseph E.; Siverd, Robert J.; Stevens, Daniel J.; Yao, Xinyu; Zhou, George; Akshay, Mundra; Aldi, Giulio F.; Ashcraft, Cliff; Awiphan, Supachai; Baştürk, Özgür; Baker, David; Beatty, Thomas G.; Benni, Paul; Berlind, Perry; Berriman, G. Bruce; Berta-Thompson, Zach; Bieryla, Allyson; Bozza, Valerio; Calchi Novati, Sebastiano; Calkins, Michael L.; Cann, Jenna M.; Ciardi, David R.; Clark, Ian R.; Cochran, William D.; Cohen, David H.; Conti, Dennis; Crepp, Justin R.; Curtis, Ivan A.; D'Ago, Giuseppe; Diazeguigure, Kenny A.; Dressing, Courtney D.; Dubois, Franky; Ellingson, Erica; Ellis, Tyler G.; Esquerdo, Gilbert A.; Evans, Phil; Friedli, Alison; Fukui, Akihiko; Fulton, Benjamin J.; Gonzales, Erica J.; Good, John C.; Gregorio, Joao; Gumusayak, Tolga; Hancock, Daniel A.; Harada, Caleb K.; Hart, Rhodes; Hintz, Eric G.; Jang-Condell, Hannah; Jeffery, Elizabeth J.; Jensen, Eric L. N.; Jofré, Emiliano; Joner, Michael D.; Kar, Aman; Kasper, David H.; Keten, Burak; Kielkopf, John F.; Komonjinda, Siramas; Kotnik, Cliff; Latham, David W.; Leuquire, Jacob; Lewis, Tiffany R.; Logie, Ludwig; Lowther, Simon J.; MacQueen, Phillip J.; Martin, Trevor J.; Mawet, Dimitri; McLeod, Kim K.; Murawski, Gabriel; Narita, Norio; Nordhausen, Jim; Oberst, Thomas E.; Odden, Caroline; Panka, Peter A.; Petrucci, Romina; Plavchan, Peter; Quinn, Samuel N.; Rau, Steve; Reed, Phillip A.; Relles, Howard; Renaud, Joe P.; Scarpetta, Gaetano; Sorber, Rebecca L.; Spencer, Alex D.; Spencer, Michelle; Stephens, Denise C.; Stockdale, Chris; Tan, Thiam-Guan; Trueblood, Mark; Trueblood, Patricia; Vanaverbeke, Siegfried; Villanueva, Steven, Jr.; Warner, Elizabeth M.; West, Mary Lou; Yalçınkaya, Selçuk; Yeigh, Rex; Zambelli, Roberto
Abstract: The Kilodegree Extremely Little Telescope (KELT) project has been conducting a photometric survey of transiting planets orbiting bright stars for over 10 years. The KELT images have a pixel scale of ∼23″ pixel^‑1-very similar to that of NASA's Transiting Exoplanet Survey Satellite (TESS)-as well as a large point-spread function, and the KELT reduction pipeline uses a weighted photometric aperture with radius 3‧. At this angular scale, multiple stars are typically blended in the photometric apertures. In order to identify false positives and confirm transiting exoplanets, we have assembled a follow-up network (KELT-FUN) to conduct imaging with spatial resolution, cadence, and photometric precision higher than the KELT telescopes, as well as spectroscopic observations of the candidate host stars. The KELT-FUN team has followed-up over 1600 planet candidates since 2011, resulting in more than 20 planet discoveries. Excluding ∼450 false alarms of non-astrophysical origin (i.e., instrumental noise or systematics), we present an all-sky catalog of the 1128 bright stars (6 < V < 13) that show transit-like features in the KELT light curves, but which were subsequently determined to be astrophysical false positives (FPs) after photometric and/or spectroscopic follow-up observations. The KELT-FUN team continues to pursue KELT and other planet candidates and will eventually follow up certain classes of TESS candidates. The KELT FP catalog will help minimize the duplication of follow-up observations by current and future transit surveys such as TESS.

ID: 150060
Type: article
Authors: Crossfield, Ian J. M.; Guerrero, Natalia; David, Trevor; Quinn, Samuel N.; Feinstein, Adina D.; Huang, Chelsea; Yu, Liang; Collins, Karen A.; Fulton, Benjamin J.; Benneke, Björn; Peterson, Merrin; Bieryla, Allyson; Schlieder, Joshua E.; Kosiarek, Molly R.; Bristow, Makennah; Newton, Elisabeth; Bedell, Megan; Latham, David W.; Christiansen, Jessie L.; Esquerdo, Gilbert A.; Berlind, Perry; Calkins, Michael L.; Shporer, Avi; Burt, Jennifer; Ballard, Sarah; Rodriguez, Joseph E.; Mehrle, Nicholas; Dressing, Courtney D.; Livingston, John H.; Petigura, Erik A.; Seager, Sara; Dittmann, Jason; Berardo, David; Sha, Lizhou; Essack, Zahra; Zhan, Zhuchang; Owens, Martin; Kain, Isabel; Isaacson, Howard; Ciardi, David R.; Gonzales, Erica J.; Howard, Andrew W.; Cardoso, José Vinícius de Miranda
Abstract: We produce light curves for all ∼34,000 targets observed with K2 in Campaign 17 (C17), identifying 34 planet candidates, 184 eclipsing binaries, and 222 other periodic variables. The forward-facing direction of the C17 field means follow-up can begin immediately now that the campaign has concluded and interesting targets have been identified. The C17 field has a large overlap with C6, so this latest campaign also offers an infrequent opportunity to study a large number of targets already observed in a previous K2 campaign. The timing of the C17 data release, shortly before science operations begin with the Transiting Exoplanet Survey Satellite (TESS), also lets us exercise some of the tools and methods developed for identification and dissemination of planet candidates from TESS. We find excellent agreement between these results and those identified using only K2-based tools. Among our planet candidates are several planet candidates with sizes _⊕ and orbiting stars with Kp ≲ 10 (indicating good RV targets of the sort TESS hopes to find) and a Jupiter-sized single-transit event around a star already hosting a 6 day planet candidate.

ID: 149407
Type: article
Authors: Irwin, Jonathan M.; Charbonneau, David; Esquerdo, Gilbert A.; Latham, David W.; Winters, Jennifer G.; Dittmann, Jason A.; Newton, Elisabeth R.; Berta-Thompson, Zachory K.; Berlind, Perry; Calkins, Michael L.
Abstract: Using data from the MEarth-North and MEarth-South transit surveys, we present the detection of eclipses in four mid M-dwarf systems: LP 107-25, LP 261-75, LP 796-24, and LP 991-15. Combining the MEarth photometry with spectroscopic follow-up observations, we show that LP 107-25 and LP 796-24 are short-period (1.388 and 0.523 day, respectively) eclipsing binaries in triple-lined systems with substantial third-light contamination from distant companions. LP 261-75 is a short-period (1.882 day) single-lined system consisting of a mid M-dwarf eclipsed by a probable brown dwarf secondary, with another distant visual brown dwarf companion. LP 991-15 is a long-period (29.3 day) double-lined eclipsing binary on an eccentric orbit with a geometry that produces only primary eclipses. A spectroscopic orbit is given for LP 991-15, and initial orbits for LP 107-25 and LP 261-75.

ID: 145777
Type: article
Authors: Mann, Andrew W.; Vanderburg, Andrew; Rizzuto, Aaron C.; Kraus, Adam L.; Berlind, Perry; Bieryla, Allyson; Calkins, Michael L.; Esquerdo, Gilbert A.; Latham, David W.; Mace, Gregory N.; Morris, Nathan R.; Quinn, Samuel N.; Sokal, Kimberly R.; Stefanik, Robert P.
Abstract: Planets in young clusters are powerful probes of the evolution of planetary systems. Here we report the discovery of three planets transiting EPIC 247589423, a late-K dwarf in the Hyades (~=800 Myr) cluster, and robust detection limits for additional planets in the system. The planets were identified from their K2 light curves as part of our survey of young clusters and star-forming regions. The smallest planet has a radius comparable to Earth ({0.99}_-0.04^+0.06{R}_\oplus ), making it one of the few Earth-sized planets with a known, young age. The two larger planets are likely a mini-Neptune and a super-Earth, with radii of {2.91}_-0.10^+0.11{R}_\oplus and {1.45}_-0.08^+0.11{R}_\oplus , respectively. The predicted radial velocity signals from these planets are between 0.4 and 2 m s^-1, achievable with modern precision RV spectrographs. Because the target star is bright (V = 11.2) and has relatively low-amplitude stellar variability for a young star (2-6 mmag), EPIC 247589423 hosts the best known planets in a young open cluster for precise radial velocity follow-up, enabling a robust test of earlier claims that young planets are less dense than their older counterparts.