Discovery of WASP-65b and WASP-75b: Two Hot Jupiters Without Highly Inflated Radii

TL;DR

This paper reports the discovery of two hot Jupiters, WASP-65b and WASP-75b, with unique properties such as high density and minimal inflation, contributing to understanding planetary structure and diversity.

Contribution

It presents the discovery and detailed characterization of two hot Jupiters with unusual radii and densities, expanding knowledge of planetary properties in the mass range around 1.5 M_J.

Findings

WASP-65b is one of the densest known exoplanets in its mass range.

WASP-75b has a radius slightly inflated compared to models without a core.

Both planets exhibit properties that challenge existing planetary inflation theories.

Abstract

We report the discovery of two transiting hot Jupiters, WASP-65b (M_pl = 1.55 +/- 0.16 M_J; R_pl = 1.11 +/- 0.06 R_J), and WASP-75b (M_pl = 1.07 +/- 0.05 M_J; R_pl = 1.27 +/- 0.05 R_J). They orbit their host star every 2.311, and 2.484 days, respectively. The planet host WASP-65 is a G6 star (T_eff = 5600 K, [Fe/H] = -0.07 +/- 0.07, age > 8 Gyr); WASP-75 is an F9 star (T_eff = 6100 K, [Fe/H] = 0.07 +/- 0.09, age of 3 Gyr). WASP-65b is one of the densest known exoplanets in the mass range 0.1 and 2.0 M_J (rho_pl = 1.13 +/- 0.08 rho_J), a mass range where a large fraction of planets are found to be inflated with respect to theoretical planet models. WASP-65b is one of only a handful of planets with masses of around 1.5 M_J, a mass regime surprisingly underrepresented among the currently known hot Jupiters. The radius of Jupiter-mass WASP-75b is slightly inflated (< 10%) as compared to theoretical planet models with no core, and has a density similar to that of Saturn (rho_pl = 0.52 +/- 0.06 rho_J).