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.
@article{arxiv.1009.5917,
title = {WASP-25b: a 0.6 M_J planet in the Southern hemisphere},
author = {B. Enoch and A. Collier Cameron and D. R. Anderson and T. A. Lister and C. Hellier and P. F. L. Maxted and D. Queloz and B. Smalley and A. H. M. J. Triaud and R. G. West and D. J. A. Brown and M. Gillon and L. Hebb and M. Lendl and N. Parley and F. Pepe and D. Pollacco and D. Segransan and E. Simpson and R. A. Street and S. Udry},
journal= {arXiv preprint arXiv:1009.5917},
year = {2015}
}