METALS IN THE EXOSPHERE OF THE HIGHLY IRRADIATED PLANET WASP-12b

Journal Article · Mon May 10 00:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/714/2/L222· OSTI ID:21448881

Fossati, L; Haswell, C A; Holmes, S; Kolb, U; Carter, A ^[1]

---

1. Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

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 A), NUVB (2655-2696 A), and NUVC (2770-2811 A). 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 2.5{sigma} level. We detect extra absorption in the Mg II {lambda}{lambda}2800 resonance line cores at the 2.8{sigma} level. The NUVA, NUVB, and NUVC light curves imply effective radii of 2.69 {+-} 0.24 R {sub J}, 2.18 {+-} 0.18 R {sub J}, and 2.66 {+-} 0.22 R {sub 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.

• OSTI ID: 21448881
• Journal Information: Astrophysical Journal Letters, Vol. 714, Issue 2; Other Information: DOI: 10.1088/2041-8205/714/2/L222; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ALUMINIUM
ASTROPHYSICS
EXOSPHERE
MAGNESIUM
MANGANESE
PLANETS
ROCHE EQUIPOTENTIALS
SCANDIUM
SODIUM
SPECTROSCOPY
STARS
TELESCOPES
TIN
VANADIUM
YTTERBIUM
ALKALI METALS
ALKALINE EARTH METALS
EARTH ATMOSPHERE
ELEMENTS
METALS
PHYSICS
POTENTIALS
RARE EARTHS
TRANSITION ELEMENTS