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TESS Reveals HD 118203 b to be a Transiting Planet

J. Pepper, S. R. Kane, J. E. Rodriguez, N. R. Hinkel, J. D. Eastman, T. Daylan, T. Mocnik, P. A. Dalba, B. S. Gaudi, Stassun K. G., T. L. Campante, A. Vanderburg, D. Huber, D. Bossini, I. J. M. Crossfield, S. B. Howell, A. W. Stephens, E. Furlan, G. R. Ricker, R. K. Vanderspek, D. W. Latham, S. Seager, J. N. Winn, J. M. Jenkins, J. D. Twicken, M. Rose, J. C. Smith, A. Glidden, A. M. Levine, S. Rinehart, K. A. Collins, A. W. Mann, J. A. Burt, D. J. James, R. J. Siverd, M. N. GŁnther

Abstract
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 1.136-0.028+0.029 RJ, and to calculate the planet mass to be 2.166-0.079+0.074 MJ. The host star is slightly evolved with an effective temperature of Teff=5683-85+84 K and a surface gravity of logg=3.8890.0180.017. With an orbital period of 6.134985-0.000030+0.000029 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.

Keywords
Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics

The Astronomical Journal
Volume 159, Number 6
2020 June

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Instituto de Astrof√≠sica e Ci√™ncias do Espa√ßo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia