VLT FORS2 COMPARATIVE TRANSMISSION SPECTROSCOPY: DETECTION OF Na IN THE ATMOSPHERE OF WASP-39b FROM THE GROUND
- Physics and Astronomy, University of Exeter, EX4 4QL Exeter (United Kingdom)
- Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom)
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
- Physics and Astronomy, University College London, London (United Kingdom)
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA (United States)
We present transmission spectroscopy of the warm Saturn-mass exoplanet WASP-39b made with the Very Large Telescope FOcal Reducer and Spectrograph (FORS2) across the wavelength range 411–810 nm. The transit depth is measured with a typical precision of 240 parts per million (ppm) in wavelength bins of 10 nm on a V = 12.1 mag star. We detect the sodium absorption feature (3.2 σ ) and find evidence of potassium. The ground-based transmission spectrum is consistent with Hubble Space Telescope ( HST ) optical spectroscopy, supporting the interpretation that WASP-39b has a largely clear atmosphere. Our results demonstrate the great potential of the recently upgraded FORS2 spectrograph for optical transmission spectroscopy, with which we obtained HST -quality light curves from the ground.
- OSTI ID:
- 22660964
- Journal Information:
- Astrophysical Journal, Vol. 832, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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