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http://hdl.handle.net/20.500.12386/32076
Titolo: | Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS). I. Detection of hot neutral sodium at high altitudes on WASP-49b | Autori: | Wyttenbach, A. Lovis, C. Ehrenreich, D. Bourrier, V. Pino, Lorenzo Allart, R. Astudillo-Defru, N. Cegla, H. M. Heng, K. Lavie, B. Melo, C. Murgas, F. Santerne, A. Ségransan, D. Udry, S. Pepe, F. |
Data pubblicazione: | 2017 | Rivista: | ASTRONOMY & ASTROPHYSICS | Numero: | 602 | Da pagina:: | A36 | Abstract: | 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 3.6 m 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% (D<SUB>2</SUB>) and 1.8 ± 0.7% (D<SUB>1</SUB>) require the presence of hot neutral sodium ( 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. <P />Based on observations made at ESO 3.6 m telescope at the La Silla Observatory under ESO program 096.C-0331.... | URI: | http://hdl.handle.net/20.500.12386/32076 | URL: | http://arxiv.org/abs/1702.00448v1 https://www.aanda.org/articles/aa/full_html/2017/06/aa30063-16/aa30063-16.html |
ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201630063 | Bibcode ADS: | 2017A&A...602A..36W | Fulltext: | open |
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