THE HOMOGENEOUS STUDY OF TRANSITING SYSTEMS (HoSTS). I. THE PILOT STUDY OF WASP-13

Abstract

We present the fundamental stellar and planetary properties of the transiting\nplanetary system WASP-13 within the framework of the Homogeneous Study of\nTransiting Systems (HoSTS). HoSTS aims to derive the fundamental stellar (Teff,\n[Fe/H], Mstar, Rstar), and planetary (Mpl, Rpl, Teq) physical properties of\nknown transiting planets using a consistent methodology and homogeneous\nhigh-quality dataset. Four spectral analysis techniques are independently\napplied to a Keck+HIRES spectrum of WASP-13 considering two distinct cases:\nunconstrained parameters, and constrained log g from transit light curves. We\ncheck the derived stellar temperature against that from a different temperature\ndiagnostic based on an INT+IDS H{\\alpha} spectrum. The four unconstrained\nanalyses render results that are in good agreement, and provide an improvement\nof 50% in the precision of Teff, and of 85% in [Fe/H] with respect to the\nWASP-13 discovery paper. The planetary parameters are then derived via the\nMonte-Carlo-Markov-Chain modeling of the radial velocity and light curves, in\niteration with stellar evolutionary models to derive realistic uncertainties.\nWASP-13 (1.187 +- 0.065 Msun; 1.574 +- 0.048 Rsun) hosts a Saturn-mass,\ntransiting planet (0.500 +- 0.037 MJup; 1.407 +- 0.052 RJup), and is at the end\nof its main-sequence lifetime (4-5.5 Gyr). Our analysis of WASP-13 showcases\nthat both a detailed stellar characterization, and transit modeling are\nnecessary to well determine the fundamental properties of planetary systems,\nwhich are paramount in identifying and determining empirical relationships\nbetween transiting planets and their hosts.\n