2008/02/29 by David K. Sing, A. Vidal‐Madjar, A. Vidal-Madjar +6 · 191 citations
Physics and Astronomy · #Absorption (acoustics) #Absorption spectroscopy #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Exoplanet #Gamma-ray bursts and supernovae #Hot Jupiter #Hubble space telescope #Limb darkening #Optics #Physics #Planet #Space Telescope Imaging Spectrograph #Spectral line #Spectrograph #Stars #Stellar, planetary, and galactic studies #Transit (satellite) #astro-ph
paper · pdf · doi:10.1086/590075
published in The Astrophysical Journal 686(1), 658-666 (IOP Publishing) · 18 pages, 11 figures, Accepted to ApJ
arxiv created 2008/05/07 · openalex publication_date 2008/10/07 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present the transmission spectra of the hot Jupiter HD 209458b taken with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope . Our analysis combines data at two resolutions and applies a complete pixel-by-pixel limb-darkening correction to fully reveal the spectral line shapes of atmospheric absorption features. Terrestrial-based Na I and H I contamination are identified that mask the strong exoplanetary absorption signature in the Na core, which we find reaches total absorption levels of ~0.11% in a 4.4 Å band. The Na spectral line profile is characterized by a wide absorption profile at the lowest absorption depths and a sharp transition to a narrow absorption profile at higher absorption values. The transmission spectra also show the presence of an additional absorber at ~6250 Å, observed at both medium and low resolutions. We performed various limb-darkening tests, including using high-precision limb-darkening measurements of the Sun to characterize a general trend of ATLAS models to slightly overestimate the amount of limb darkening at all wavelengths, likely due to the limitations of the model's one-dimensional nature. We conclude that, despite these limitations, ATLAS models can still successfully model limb darkening in high signal-to-noise ratio transits of solar-type stars, like HD 209458, to a high level of precision over the entire optical regime (3000-10000 Å) at transit phases between second and third contact.