High-precision transit observations of the exoplanet WASP-13b with the RISE instrument

Journal article

WASP-13b is a sub-Jupiter mass exoplanet orbiting a G1V type star with a period of 4.35d. The current uncertainty in its impact parameter (0 < b < 0.46) results in poorly defined stellar and planetary radii. To better constrain the impact parameter, we have obtained high-precision transit observations with the rapid imager to search for exoplanets (RISE) instrument mounted on 2.0-m Liverpool Telescope. We present four new transits which are fitted with a Markov chain Monte Carlo routine to derive accurate system parameters. We found an orbital inclination of 852 ± 03 resulting in stellar and planetary radii of 1.56 ± 0.04R⊙ and 1.39 ± 0.05RJup, respectively. This suggests that the host star has evolved off the main sequence and is in the hydrogen-shell-burning phase. We also discuss how the limb darkening affects the derived system parameters. With a density of 0.17ρJ, WASP-13b joins the group of low-density planets whose radii are too large to be explained by standard irradiation models. We derive a new ephemeris for the system, T0= 2455575.5136 ± 0.0016 (HJD) and P= 4.353011 ± 0.000013d. The planet equilibrium temperature (Tequ= 1500K) and the bright host star (V= 10.4mag) make it a good candidate for follow-up atmospheric studies. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

Authors: Barros, S; Pollacco, D; Gibson, N; Keenan, F; Skillen, I

• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 419
• Issue: 2
• Pages: 1248-1253
• Publication date: 2012-01-01
• DOI: 10.1111/j.1365-2966.2011.19784.x
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: Techniques: photometric; Planetary systems; Methods: data analysis; Stars: individual: WASP-13; Methods: observational