Hostname: page-component-7c8c6479df-7qhmt Total loading time: 0 Render date: 2024-03-29T00:42:02.712Z Has data issue: false hasContentIssue false

Transmission spectroscopy of the sodium doublet in WASP-17b with the VLT

Published online by Cambridge University Press:  10 November 2011

Patricia L. Wood
Affiliation:
Keele University, Staffordshire ST5 5BG, UK email: plw@astro.keele.ac.uk
Pierre F. L. Maxted
Affiliation:
Keele University, Staffordshire ST5 5BG, UK email: plw@astro.keele.ac.uk
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The detection of sodium absorption during primary transit implies the presence of an atmosphere around an extrasolar planet. WASP-17b (Anderson et al. 2010a) is the least dense known planet, with a radius twice that of Jupiter. It orbits an F6-type star, and its low gravity gives its atmosphere a very large scale height. The sodium transit depth is expected to be 4.1 – 5.2 times deeper than for HD 209458b (Seager & Sasselov 2000). We obtained 24 spectra with the GIRAFFE spectrograph on the VLT, 8 during transit. We measured the flux in the sodium doublet at 5889.95 Å and 5895.92 Å using bandpasses 0.75, 1.5, 3.0 and 6.0 Å. We find a transit depth of 0.55±0.13% at 1.5 Å (4.3σ). WASP-17b therefore has an atmosphere which is depleted in sodium compared to predictions.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

References

Anderson, D. R., et al. 2010a, ApJ, 709, 159CrossRefGoogle Scholar
Anderson, D. R., et al. 2010b, in prep.Google Scholar
Seager, S. & Sasselov, D. D. 2000, ApJ, 540, 504Google Scholar
Redfield, S., Endl, M., Cochran, W. D., & Koesterke, L. 2008, AJ, 673, L87Google Scholar
Snellen, I. A. G., Albrecht, S., de Mooji, E. J. W. & Le Poole, R. S. 2008, A&A, 487, 357Google Scholar