WASP-25b: a 0.6 M_J planet in the Southern hemisphere

TL;DR

WASP-25b is a newly discovered 0.6 Jupiter-mass exoplanet with a low density, orbiting a solar-type star, and the study explores how planetary radius relates to temperature and metallicity.

Contribution

This paper reports the discovery and detailed characterization of WASP-25b, including its mass, radius, density, and host star properties, and analyzes factors influencing low-mass planet radii.

Findings

WASP-25b has a mass of 0.58 M_J and radius of 1.22 R_J.

The planet's density is low at 0.32 times Jupiter's density.

Planetary radius correlates with equilibrium temperature and host star metallicity.

Abstract

We report the detection of a 0.6 M_J extrasolar planet by WASP-South, WASP-25b, transiting its solar-type host star every 3.76 days. A simultaneous analysis of the WASP, FTS and Euler photometry and CORALIE spectroscopy yields a planet of R_p = 1.22 R_J and M_p = 0.58 M_J around a slightly metal-poor solar-type host star, [Fe/H] = -0.05 \pm 0.10, of R_{\ast} = 0.92 R_{\odot} and M_{\ast} = 1.00 M_{\odot}. WASP-25b is found to have a density of \rho_p = 0.32 \rho_J, a low value for a sub-Jupiter mass planet. We investigate the relationship of planetary radius to planetary equilibrium temperature and host star metallicity for transiting exoplanets with a similar mass to WASP-25b, finding that these two parameters explain the radii of most low-mass planets well.