The Transiting Multi-planet System HD15337: Two Nearly Equal-mass Planets Straddling the Radius Gap

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Authors	GANDOLFI Davide FOSSATI Luca LIVINGSTON John H. STASSUN Keivan G. GRZIWA Sascha BARRAGAN Oscar FRIDLUND Malcolm KUBYSHKINA Daria PERSSON Carina M. DAI Fei LAM Kristine W. F. ALBRECHT Simon BATALHA Natalie BECK Paul G. JUSTESEN Anders Bo CABRERA Juan CARTWRIGHT Scott COCHRAN William D. CSIZMADIA Szilard DAVIES Misty D. DEEG Hans J. EIGMUELLER Philipp ENDL Michael ERIKSON Anders ESPOSITO Massimiliano GARCIA Rafael A. GOEKE Robert GONZALEZ-CUESTA Lucia GUENTHER Eike W. HATZES Artie P. HIDALGO Diego HIRANO Teruyuki HJORTH Maria KABATH Petr KNUDSTRUP Emil KORTH Judith LI Jie LUQUE Rafael MATHUR Savita MONTANES Rodriguez Pilar NARITA Norio NESPRAL David NIRAULA Prajwal NOWAK Grzegorz PALLE Enric PAETZOLD Martin PRIETO-ARRANZ Jorge RAUER Heike REDFIELD Seth RIBAS Ignasi SKARKA Marek SMITH Alexis M. S. ROWDEN Pamela TORRES Guillermo VAN Eylen Vincent VEZIE Michael L.
Year of publication	2019
Type	Article in Periodical
Magazine / Source	ASTROPHYSICAL JOURNAL LETTERS
MU Faculty or unit	Faculty of Science
Citation
Web	Full Text
Doi	http://dx.doi.org/10.3847/2041-8213/ab17d9
Keywords	planetary systems; planets and satellites: detection; planets and satellites: fundamental parameters; planets and satellites: individual (HD15337 b & c); stars: fundamental parameters
Description	We report the discovery of a super-Earth and a sub-Neptune transiting the star HD 15337 (TOI-402, TIC 120896927), a bright (V = 9) K1 dwarf observed by the Transiting Exoplanet Survey Satellite (TESS) in Sectors 3 and 4. We combine the TESS photometry with archival High Accuracy Radial velocity Planet Searcher spectra to confirm the planetary nature of the transit signals and derive the masses of the two transiting planets. With an orbital period of 4.8 days, a mass of 7.51(-1.01)(+1.09) M-circle plus and a radius of 1.64 +/- 0.06 R-circle plus, HD 15337 b joins the growing group of short-period super-Earths known to have a rocky terrestrial composition. The sub-Neptune HD 15337 c has an orbital period of 17.2 days, a mass of 8.11(-1.69)(+1.82) M-circle plus, and a radius of 2.39 +/- 0.12 R-circle plus, suggesting that the planet might be surrounded by a thick atmospheric envelope. The two planets have similar masses and lie on opposite sides of the radius gap, and are thus an excellent testbed for planet formation and evolution theories. Assuming that HD 15337 c hosts a hydrogen-dominated envelope, we employ a recently developed planet atmospheric evolution algorithm in a Bayesian framework to estimate the history of the high-energy (extreme ultraviolet and X-ray) emission of the host star. We find that at an age of 150 Myr, the star possessed on average between 3.7 and 127 times the high-energy luminosity of the current Sun.
Related projects:	Postdoc@MUNI