Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)

Wyttenbach, A.; Lovis, C.; Ehrenreich, D.; Bourrier, V.; Pino, L.; Allart, R.; Astudillo-Defru, N.; Cegla, H. M.; Heng, Kevin; Lavie, B.; Melo, C.; Murgas, F.; Santerne, A.; Ségransan, D.; Udry, S.; Pepe, F. (2017). Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS). Astronomy and astrophysics, 602(A36), A36. EDP Sciences 10.1051/0004-6361/201630063

Preview	Text 1702.00448.pdf - Accepted Version Available under License Publisher holds Copyright. Download (1MB) | Preview
	Text aa30063-16.pdf - Published Version Restricted to registered users only Available under License Publisher holds Copyright. Download (1MB) | Request a copy

High-resolution optical spectroscopy during the transit of HD 189733b, a prototypical hot Jupiter, allowed the resolution of the Na I D sodium lines in the planet, giving access to the extreme conditions of the planet upper atmosphere. We have undertaken HEARTS, a spectroscopic survey of exoplanet upper atmospheres, to perform a comparative study of hot gas giants and determine how stellar irradiation affect them. Here, we report on the first HEARTS observations of the hot Saturn-mass planet WASP-49b. We observed the planet with the HARPS high-resolution spectrograph at ESO 3.6m telescope. We collected 126 spectra of WASP-49, covering three transits of WASP-49b. We analyzed and modeled the planet transit spectrum, while paying particular attention to the treatment of potentially spurious signals of stellar origin. We spectrally resolve the Na I D lines in the planet atmosphere and show that these signatures are unlikely to arise from stellar contamination. The large contrasts of 2.0±0.5% (D₂) and 1.8±0.7% (D₁) require the presence of hot neutral sodium (2,950+400−500 K) at high altitudes (~1.5 planet radius or ~45,000 km). From estimating the cloudiness index of WASP-49b, we determine its atmosphere to be cloud free at the altitudes probed by the sodium lines. WASP-49b is close to the border of the evaporation desert and exhibits an enhanced thermospheric signature with respect to a farther-away planet such as HD 189733b.

Interest & Impact

Downloads

302 since deposited on 18 Apr 2018
12 in the past 12 months

Citations

5 Citations in Web of Science ®
6 Citations in Scopus

Search

in Google Scholar™

Services

Actions (login required)

Edit item

Actions (login required)

Edit item