2015/08/24 by S. Czesla, T. Klocová, S. Khalafinejad +3 · 94 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Brightness #Giant planet #Optics #Physics #Planet #Planetary system #Spectral line #Spectroscopy #Stellar, planetary, and galactic studies #Wavelength #astro-ph.EP #astro-ph.SR
paper · pdf · doi:10.1051/0004-6361/201526386
published in Astronomy and Astrophysics 582, A51 (EDP Sciences) · Accepted in A&A
openalex publication_date 2015/08/24 · arxiv created 2015/09/18 · arxiv updated 2015/10/14 · openalex created_date 2022/08/27 · openalex updated_date 2026/08/01
The center-to-limb variation (CLV) describes the brightness of the stellar disk as a function of the limb angle. Across strong absorption lines, the CLV can vary quite significantly. We obtained a densely sampled time series of high-resolution transit spectra of the active planet host star HD 189733 with UVES. Using the passing planetary disk of the hot Jupiter HD 189733 b as a probe, we study the CLV in the wings of the Ca ii H and K and Na i D1 and D2 Fraunhofer lines, which are not strongly affected by activity-induced variability. In agreement with model predictions, our analysis shows that the wings of the studied Fraunhofer lines are limb brightened with respect to the (quasi-)continuum. The strength of the CLV-induced effect can be on the same order as signals found for hot Jupiter atmospheres. Therefore, a careful treatment of the wavelength dependence of the stellar CLV in strong absorption lines is highly relevant in the interpretation of planetary transit spectroscopy.