Hydrogen and Sodium Absorption in the Optical Transmission Spectrum of WASP-12b

Adam G Jensen, P. Wilson Cauley, Seth Redfield, William D. Cochran, Michael Endl

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We have obtained >10 hr of medium-resolution (R ∼ 15,000) spectroscopic exposures on the transiting exoplanet host star WASP-12, including ∼2 hr while its planet, WASP-12b, is in transit, with the Hobby-Eberly Telescope. The out-of-transit and in-transit spectra are coadded into master out-of-transit and in-transit spectra, from which we create a master transmission spectrum. Strong, statistically significant absorption features are seen in the transmission spectrum at Hα and Na i (the Na D doublet). There is the suggestion of pre- and post-transit absorption in both Hα and Na i when the transmission spectrum is examined as a function of phase. The timing of the pretransit absorption is roughly consistent with previous results for metal absorption in WASP-12b, and the level of the Na i absorption is consistent with a previous tentative detection. No absorption is seen in the control line of Ca i at λ6122. We discuss in particular whether or not the WASP-12b Hα absorption signal is of circumplanetary origin - an interpretation that is bolstered by the pre- and post-transit evidence - which would make it one of only a small number of detections of circumplanetary Hα absorption in an exoplanet to date, the most well-studied being HD 189733b. We further discuss the notable differences between the HD 189733 and WASP-12 systems and the implications for a physical understanding of the origin of the absorption.

Original languageEnglish (US)
Article number154
JournalAstronomical Journal
Volume156
Issue number4
DOIs
StatePublished - Oct 1 2018

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transit
sodium
hydrogen
extrasolar planets
suggestion
planets
planet
time measurement
telescopes
stars
metal
metals

Keywords

  • planetary systems
  • planets and satellites: atmospheres
  • planets and satellites: gaseous planets
  • techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Hydrogen and Sodium Absorption in the Optical Transmission Spectrum of WASP-12b. / Jensen, Adam G; Wilson Cauley, P.; Redfield, Seth; Cochran, William D.; Endl, Michael.

In: Astronomical Journal, Vol. 156, No. 4, 154, 01.10.2018.

Research output: Contribution to journalArticle

Jensen, Adam G ; Wilson Cauley, P. ; Redfield, Seth ; Cochran, William D. ; Endl, Michael. / Hydrogen and Sodium Absorption in the Optical Transmission Spectrum of WASP-12b. In: Astronomical Journal. 2018 ; Vol. 156, No. 4.
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