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TESS Reveals HD 118203 b to be a Transiting Planet

Pepper, Joshua and Kane, Stephen R. and Rodriguez, Joseph E. and Hinkel, Natalie R. and Eastman, Jason D. and Daylan, Tansu and Mocnik, Teo and Dalba, Paul A. and Gaudi, B. Scott and Fetherolf, Tara and Stassun, Keivan G. and Campante, Tiago L. and Vanderburg, Andrew and Huber, Daniel and Bossini, Diego and Crossfield, Ian and Howell, Steve B. and Stephens, Andrew W. and Furlan, E. and Ricker, George R. and Vanderspek, Roland and Latham, David W. and Seager, S. and Winn, Joshua N. and Jenkins, Jon M. and Twicken, Joseph D. and Rose, Mark and Smith, Jeffrey C. and Glidden, Ana and Levine, Alan M. and Rinehart, Stephen and Collins, Karen A. and Mann, Andrew W. and Burt, Jennifer A. and James, David J. and Siverd, Robert J. and Günther, Maximilian N. (2020) TESS Reveals HD 118203 b to be a Transiting Planet. Astronomical Journal, 159 (6). Art. No. 243. ISSN 1538-3881.

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The exoplanet HD 118203 b, orbiting a bright (V = 8.05) host star, was discovered using the radial velocity method by da Silva et al., but was not previously known to transit. Transiting Exoplanet Survey Satellite (TESS) photometry has revealed that this planet transits its host star. Nine planetary transits were observed by TESS, allowing us to measure the radius of the planet to be 1.136^(+0.029)_(-0.028) R_J, and to calculate the planet mass to be 2.166^(+0.074)_(-0.079) M_J. The host star is slightly evolved with an effective temperature of T_(eff) = 5683^(+84)_(-85) K and a surface gravity of log g = 3.889^(+0.017)_(-0.018). With an orbital period of 6.134985^(+0.000029_(-0.000030) days and an eccentricity of 0.314 ± 0.017, the planet occupies a transitional regime between circularized hot Jupiters and more dynamically active planets at longer orbital periods. The host star is among the 10 brightest known to have transiting giant planets, providing opportunities for both planetary atmospheric and asteroseismic studies.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Pepper, Joshua0000-0002-3827-8417
Kane, Stephen R.0000-0002-7084-0529
Rodriguez, Joseph E.0000-0001-8812-0565
Hinkel, Natalie R.0000-0003-0595-5132
Eastman, Jason D.0000-0003-3773-5142
Daylan, Tansu0000-0002-6939-9211
Mocnik, Teo0000-0003-4603-556X
Dalba, Paul A.0000-0002-4297-5506
Gaudi, B. Scott0000-0003-0395-9869
Stassun, Keivan G.0000-0002-3481-9052
Campante, Tiago L.0000-0002-4588-5389
Vanderburg, Andrew0000-0001-7246-5438
Huber, Daniel0000-0001-8832-4488
Bossini, Diego0000-0002-9480-8400
Crossfield, Ian0000-0002-1835-1891
Howell, Steve B.0000-0002-2532-2853
Stephens, Andrew W.0000-0002-4434-2307
Furlan, E.0000-0001-9800-6248
Ricker, George R.0000-0003-2058-6662
Vanderspek, Roland0000-0001-6763-6562
Latham, David W.0000-0001-9911-7388
Seager, S.0000-0002-6892-6948
Winn, Joshua N.0000-0002-4265-047X
Jenkins, Jon M.0000-0002-4715-9460
Twicken, Joseph D.0000-0002-6778-7552
Rose, Mark0000-0003-4724-745X
Smith, Jeffrey C.0000-0002-6148-7903
Glidden, Ana0000-0002-5322-2315
Collins, Karen A.0000-0001-6588-9574
Mann, Andrew W.0000-0003-3654-1602
Burt, Jennifer A.0000-0002-0040-6815
James, David J.0000-0001-5160-4486
Siverd, Robert J.0000-0001-5016-3359
Günther, Maximilian N.0000-0002-3164-9086
Additional Information:© 2020 The American Astronomical Society. Received 2019 November 1; revised 2020 March 25; accepted 2020 March 26; published 2020 May 1. We would like to thank Avi Shporer and Chelsea Huang for helpful conversations. This paper includes data collected with the TESS mission, obtained from the MAST data archive at the Space Telescope Science Institute (STScI). Funding for the TESS mission is provided by the NASA Explorer Program. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 526555. T.D. acknowledges support from MIT's Kavli Institute as a Kavli postdoctoral fellow. A.V.'s work was performed under contract with the California Institute of Technology/Jet Propulsion Laboratory funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. D.H. acknowledges support by the National Aeronautics and Space Administration (80NSSC18K1585, 80NSSC19K0379) awarded through the TESS Guest Investigator Program and by the National Science Foundation (AST-1717000). T.L.C. acknowledges support from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 792848 (PULSATION). This work was supported by FCT/MCTES through national funds (UID/FIS/04434/2019). D.B. is supported in the form of work contract FCT/MCTES through national funds and by FEDER through COMPETE2020 in connection to these grants: UID/FIS/04434/2019, PTDC/FIS-AST/30389/2017, and POCI-01-0145-FEDER-030389. P.D. is supported by a National Science Foundation (NSF) Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1903811. M.N.G. acknowledges support from MIT's Kavli Institute as a Torres postdoctoral fellow. This work has made use of NASA's Astrophysics Data System, the SIMBAD database operated at CDS, Strasbourg, France, and the VizieR catalog access tool, CDS, Strasbourg, France. We acknowledge the use of public TESS Alert data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. We make use of Filtergraph, an online data visualization tool developed at Vanderbilt University through the Vanderbilt Initiative in Data-intensive Astrophysics (VIDA). The research shown here acknowledges use of the Hypatia Catalog Database, an online compilation of stellar abundance data as described in Hinkel et al. (2014), which was supported by NASA's Nexus for Exoplanet System Science (NExSS) research coordination network and the Vanderbilt Initiative in Data-Intensive Astrophysics (VIDA). This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This publication makes use of The Data & Analysis Center for Exoplanets (DACE), which is a facility based at the University of Geneva (CH) dedicated to extrasolar planets data visualization, exchange, and analysis. DACE is a platform of the Swiss National Centre of Competence in Research (NCCR) PlanetS, federating the Swiss expertise in Exoplanet research. The DACE platform is available at Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). Some of the Observations in the paper made use of the High-Resolution Imaging instrument Alopeke at Gemini-North. Alopeke was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. This research made use of Astropy,38 a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018). We also used data products from the Widefield Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles; the Jet Propulsion Laboratory/California Institute of Technology, which is funded by the National Aeronautics and Space Administration; the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation; and the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. We acknowledge support for the KELT project through the Vanderbilt Initiative in Data-intensive Astrophysics, Ohio State University, and Lehigh University. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASANAS 5-26555
Massachusetts Institute of Technology (MIT)UNSPECIFIED
Marie Curie Fellowship792848
Fundação para a Ciência e a Tecnologia (FCT)UID/FIS/04434/2019
Ministério da Ciência, Tecnologia e Ensino Superio (MCTES)UNSPECIFIED
Fondo Europeo de Desarrollo Regional (FEDER)PTDC/FIS-AST/30389/2017
Fondo Europeo de Desarrollo Regional (FEDER)POCI-01-0145-FEDER-030389
NSF Astronomy and Astrophysics FellowshipAST-1903811
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:Exoplanet astronomy ; Exoplanet systems ; Transit photometry
Issue or Number:6
Classification Code:Unified Astronomy Thesaurus concepts: Exoplanet astronomy (486); Exoplanet systems (484); Transit photometry (1709)
Record Number:CaltechAUTHORS:20200504-105650720
Persistent URL:
Official Citation:Joshua Pepper et al 2020 AJ 159 243
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102974
Deposited By: Tony Diaz
Deposited On:04 May 2020 20:12
Last Modified:04 May 2020 20:12

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