Transmission spectroscopy of the inflated exoplanet WASP-52b, and evidence for a bright region on the stellar surface
Abstract
We have measured the transmission spectrum of the extremely inflated hot Jupiter WASP-52b using simultaneous photometric observations in Sloan Digital Sky Survey u', g' and a filter centred on the sodium doublet (Na I) with the ULTRACAM instrument mounted on the 4.2-m William Herschel Telescope. We find that Rayleigh scattering is not the dominant source of opacity within the planetary atmosphere and find a transmission spectrum more consistent with wavelength-independent opacity such as from clouds. We detect an in-transit anomaly that we attribute to the presence of stellar activity and find that this feature can be more simply modelled as a bright region on the stellar surface akin to solar faculae rather than spots. A spot model requires a significantly larger planet/star radius ratio than that found in previous studies. Our results highlight the precision that can be achieved by ground-based photometry with errors in the scaled planetary radii of less than one atmospheric scale height, comparable to Hubble Space Telescope observations.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 2016
- DOI:
- 10.1093/mnras/stw2205
- arXiv:
- arXiv:1608.08993
- Bibcode:
- 2016MNRAS.463.2922K
- Keywords:
-
- stars: individual: WASP-52;
- planetary systems;
- starspots;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Accepted for publication in MNRAS. 11 pages, 6 figures, 2 tables