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

TL;DR

HAT-P-10b is a low-mass, moderately hot Jupiter orbiting a K dwarf, notable for its low density and status as one of the coldest transiting exoplanets discovered, with implications for planetary structure models.

Contribution

This paper reports the discovery and characterization of HAT-P-10b, the lowest mass transiting exoplanet found by transit surveys, providing new data on its physical properties and comparison with theoretical models.

Findings

Lowest mass transiting exoplanet discovered to date.

HAT-P-10b has a low density of 0.498 g/cm^3.

It is one of the coldest known transiting exoplanets.

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.