Refined stellar, orbital and planetary parameters of the eccentric HAT-P-2 planetary system

TL;DR

This paper refines the parameters of the eccentric exoplanet HAT-P-2b and its host star using new data, providing improved orbital and physical characteristics crucial for understanding its dynamics and observational predictions.

Contribution

It offers the first comprehensive refinement of stellar and planetary parameters for HAT-P-2b, including orbital eccentricity and transit timing, based on new radial velocity and photometric data.

Findings

Refined stellar mass and radius: M_star = 1.36 M_sun, R_star = 1.64 R_sun

Refined planetary mass and radius: M_p = 9.09 M_Jup, R_p = 1.16 R_Jup

Accurate predictions of secondary eclipse timings within ~15 minutes

Abstract

We present refined parameters for the extrasolar planetary system HAT-P-2 (also known as HD 147506), based on new radial velocity and photometric data. HAT-P-2b is a transiting extrasolar planet that exhibits an eccentric orbit. We present a detailed analysis of the planetary and stellar parameters, yielding consistent results for the mass and radius of the star, better constraints on the orbital eccentricity, and refined planetary parameters. The improved parameters for the host star are M_star = 1.36 +/- 0.04 M_sun and R_star = 1.64 +/- 0.08 R_sun, while the planet has a mass of M_p = 9.09 +/- 0.24 M_Jup and radius of R_p = 1.16 +/- 0.08 R_Jup. The refined transit epoch and period for the planet are E = 2,454,387.49375 +/- 0.00074 (BJD) and P = 5.6334729 +/- 0.0000061 (days), and the orbital eccentricity and argument of periastron are e = 0.5171 +/- 0.0033 and omega = 185.22 +/- 0.95 degrees. These orbital elements allow us to predict the timings of secondary eclipses with a reasonable accuracy of ~15 minutes. We also discuss the effects of this significant eccentricity including the characterization of the asymmetry in the transit light curve. Simple formulae are presented for the above, and these, in turn, can be used to constrain the orbital eccentricity using purely photometric data. These will be particularly useful for very high precision, space-borne observations of transiting planets.