Back to Volume
Paper: The Hobby-Eberly Telescope (HET) Delivers the First Ground-Based Detection of an Exoplanetary Atmosphere
Volume: 393, New Horizons in Astronomy: Frank N. Bash Symposium 2007
Page: 259
Authors: Redfield, S.; Endl, M.; Cochran, W.D.; Koesterke, L.
Abstract: We present the first ground-based detection of absorption in the optical transmission spectrum caused by the atmosphere of the transiting extrasolar planet around HD189733. We combine multiple in-transit observations taken by the 9.2m Hobby-Eberly Telescope (HET) High Resolution Spectrograph (HRS) and compare directly with out-of-transit observations. We detect a significant excess of absorption in the Na I doublet for in-transit observations, relative to the out-of-transit observations. A strong control line is also analyzed, and shows no variation between in- and out-of-transit observations. We also present empirical Monte Carlo simulations, where our large sample of out-of-transit observations are used to estimate the systematic errors involved in our analysis. With no currently operating high resolution space-based optical or ultraviolet spectrographs, ground-based facilities provide the only opportunity to probe the extrasolar atmospheric signatures in the visible waveband. Measurements, and even upper limits, of atmospheric lines should provide important constraints on models of giant exoplanet atmospheres, including for example, cloud cover altitudes, atomic and molecular composition, and temperature profiles. Full details can be found in Redfield et al. (2008).
Back to Volume