HAT-P-3b: A heavy-element rich planet transiting a K dwarf star

TL;DR

This paper reports the discovery and characterization of HAT-P-3b, a Jupiter-sized exoplanet with a high heavy-element content orbiting a bright K dwarf star, providing insights into planetary composition and structure.

Contribution

It presents the first detailed measurements of HAT-P-3b's mass, radius, and heavy-element content, highlighting its high metallicity and dense composition compared to similar exoplanets.

Findings

HAT-P-3b has a mass of 0.599 Jupiter masses.

The planet's radius is 0.890 Jupiter radii.

It contains about 75 Earth masses of heavy elements.

Abstract

We report the discovery of a Jupiter-size planet transiting a relatively bright (V = 11.56) and metal-rich early K dwarf star with a period of about 2.9 days. On the basis of follow-up photometry and spectroscopy we determine the mass and radius of the planet, HAT-P-3b, to be M_p = 0.599 +/- 0.026 M_Jup and R_p = 0.890 +/- 0.046 R_Jup. The relatively small size of the object for its mass implies the presence of about 75 Earth masses worth of heavy elements (1/3 of the total mass) based on current theories of irradiated extrasolar giant planets, similar to the mass of the core inferred for the transiting planet HD 149026b. The bulk density of HAT-P-3b is found to be rho_p = 1.06 +/- 0.17 g/cm^3, and the planet orbits the star at a distance of 0.03894 AU. Ephemerides for the transit centers are T_c = 2,454,218.7594 +/- 0.0029 + N (2.899703 +/- 0.000054) (HJD).