HAT-P-10b: A light and moderately hot Jupiter transiting a K dwarf

astro-ph

/ Authors

G. A. Bakos, A. Pal, G. Torres, B. Sipocz, D. W. Latham, R. W. Noyes, Geza Kovacs, J. Hartman, G. A. Esquerdo, D. A. Fischer

and 10 more authors

J. A. Johnson, G. W. Marcy, R. P. Butler, A. Howard, D. D. Sasselov, Gabor Kovacs, R. P. Stefanik, J. Lazar, I. Papp, P. Sari

/ Abstract

We report on the discovery of HAT-P-10b, the lowest mass (0.46 +/- 0.03 MJ) transiting extrasolar planet (TEP) discovered to date by transit searches. HAT-P-10b orbits the moderately bright V=11.89 K dwarf GSC 02340-01714, with a period P = 3.7224690 +/- 0.0000067 d, transit epoch Tc = 2454729.90631 +/- 0.00030 (BJD) and duration 0.1100 +/- 0.0015 d. HAT-P-10b has a radius of 1.05 +(0.05)-(0.03) RJ yielding a mean density of 0.498+/-0.064 g cm^-3 . Comparing these observations with recent theoretical models we find that HAT-P-10 is consistent with a ~4.5 Gyr, coreless, pure hydrogen and helium gas giant planet. With an equilibrium temperature of Teq = 1030 +(26)-(19)K, HAT-P-10b is one of the coldest TEPs. Curiously, its Safronov number Theta = 0.047 +/- 0.003 falls close to the dividing line between the two suggested TEP populations.