The 0.5M${}_J$ transiting exoplanet WASP-13b

Abstract

We report the discovery of WASP-13b, a low-mass $M_p=0.46_{-0.05}^{+0.06}{M}_J$ transiting exoplanet with an orbital period of $4.35298\pm 0.00004$ days. The transit has a depth of 9 mmag, and although our follow-up photometry does not allow us to constrain the impact parameter well ($0<b<0.46$), with radius in the range $R_p\sim 1.06-1.21R_J$ the location of WASP-13b in the mass-radius plane is nevertheless consistent with H/He-dominated, irradiated, low core mass and core-free theoretical models. The G1V host star is similar to the Sun in mass (M${}_{\ast }=1.03_{-0.09}^{+0.11}{M}_{\odot }$) and metallicity ([M/H]=$0.0\pm 0.2$), but is possibly older ($8.5_{-4.9}^{+5.5}$ Gyr).

4 pages. Accepted for publication in Astronomy and Astrophysics