WASP-39b: a highly inflated Saturn-mass planet orbiting a late G-type star
Abstract
We present the discovery of WASP-39b, a highly inflated transiting Saturn-mass planet orbiting a late G-type dwarf star with a period of 4.055259 ± 0.000008 d, Transit Epoch T0 = 2 455 342.9688 ± 0.0002 (HJD), of duration 0.1168 ± 0.0008 d. A combined analysis of the WASP photometry, high-precision follow-up transit photometry, and radial velocities yield a planetary mass of Mpl = 0.28 ± 0.03 MJ and a radius of Rpl = 1.27 ± 0.04 RJ, resulting in a mean density of 0.14 ± 0.02 ρJ. The stellar parameters are mass M⋆ = 0.93 ± 0.03 M⊙, radius R⋆ = 0.895 ± 0.23 R⊙, and age 9+3-4 Gyr. Only WASP-17b and WASP-31b have lower densities than WASP-39b, although they are slightly more massive and highly irradiated planets. From our spectral analysis, the metallicity of WASP-39 is measured to be [Fe/H] = -0.12 ± 0.1 dex, and we find the planet to have an equilibrium temperature of 1116+33-32 K. Both values strengthen the observed empirical correlation between these parameters and the planetary radius for the known transiting Saturn-mass planets.
Spectroscopic and photometric data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A40- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- July 2011
- DOI:
- 10.1051/0004-6361/201116671
- arXiv:
- arXiv:1102.1375
- Bibcode:
- 2011A&A...531A..40F
- Keywords:
-
- stars: individual: WASP-39;
- techniques: photometric;
- techniques: radial velocities;
- planetary systems;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 7 pages, 6 figures, submitted to A&