Year: 2010
Type: article
Abstract: We present near-UV transmission spectroscopy of the highly irradiated transiting exoplanet WASP-12b, obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope . The spectra cover three distinct wavelength ranges: NUVA (2539–2580 Å), NUVB (2655–2696 Å), and NUVC (2770–2811 Å). Three independent methods all reveal enhanced transit depths attributable to absorption by resonance lines of metals in the exosphere of WASP-12b. Light curves of total counts in the NUVA and NUVC wavelength ranges show a detection at a 2.5σ level. We detect extra absorption in the Mg ii λλ2800 resonance line cores at the 2.8σ level. The NUVA, NUVB, and NUVC light curves imply effective radii of 2.69 ± 0.24 R J , 2.18 ± 0.18 R J , and 2.66 ± 0.22 R J respectively, suggesting the planet is surrounded by an absorbing cloud which overfills the Roche lobe. We detect enhanced transit depths at the wavelengths of resonance lines of neutral sodium, tin, and manganese, and at singly ionized ytterbium, scandium, manganese, aluminum, vanadium, and magnesium. We also find the statistically expected number of anomalous transit depths at wavelengths not associated with any known resonance line. Our data are limited by photon noise, but taken as a whole the results are strong evidence for an extended absorbing exosphere surrounding the planet. The NUVA data exhibit an early ingress, contrary to model expectations; we speculate this could be due to the presence of a disk of previously stripped material.
Authors: L. Fossati, C. A. Haswell, C. S. Froning, L. Hebb, S. Holmes, U. Kolb, Ch. Helling, A. Carter, P. Wheatley, A. C. Cameron, B. Loeillet, D. Pollacco, R. Street, H. C. Stempels, E. Simpson, S. Udry, Y. C. Joshi, R. G. West, I. Skillen, D. Wilson
Institutions: The Open University, University of Colorado Boulder, Vanderbilt University, University of St Andrews, University of Warwick, Centre National de la Recherche Scientifique, Laboratoire d’Astrophysique de Marseille, Université de Provence Aix-Marseille I, Queen's University Belfast, Las Cumbres Observatory Global Telescope Network, University of Geneva, University of Leicester, Isaac Newton Group, Keele University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: Warwick Astronomy and Astrophysics Rolling Grant 2008-2013, Project support for the Wide Area Search for Planets, Open University Rolling Grant 2009 - 2014, G4287467742, G433322167, G4518818167, G58316358, G6273510985, Project support for the Wide Area Search for Planets, G767601387, Bridging for Dr R West for WASP, G8509441750
OpenAlex ID: W2950620951