HATS9-b and HATS10-b: Two compact hot Jupiters in field 7 of the K2 mission

Abstract

We report the discovery of two transiting extrasolar planets by the HATSouth survey. HATS-9b orbits an old (10.8 ± 1.5 Gyr) V = 13.3 G dwarf star with a period days. The host star has a mass of 1.03 M⊙, radius of 1.503 R⊙, and effective temperature 5366 ± 70 K. The planetary companion has a mass of 0.837 <inf>Mj</inf> and radius of 1.065 R<inf>j</inf>, yielding a mean density of 0.85g cm-3. HATS-10b orbits a V = 13.1 G dwarf star with a period days. The host star has a mass of 1.1 M⊙, radius of 1.11 R⊙, and effective temperature 5880 ± 120 K. The planetary companion has a mass of 0.53 and radius of 0.97 , yielding a mean density of 0.7 g cm-3. Both planets are compact in comparison with planets receiving similar irradiation from their host stars and lie in the nominal coordinates of Field 7 of K2, but only HATS-9b falls on working silicon. Future characterization of HATS-9b with the exquisite photometric precision of the Kepler telescope may provide measurements of its reflected light signature.