Doppler Tomography As a Tool for Characterising Exoplanet Atmospheres II: an Analysis of HD 179949 B

High-resolution Doppler spectroscopy provides an avenue to study theatmosphere of both transiting and non-transiting planets. This powerful methodhas also yielded some of the most robust atmospheric detections to date.Currently, high-resolution Doppler spectroscopy detects atmospheric signals bycross-correlating observed data with a model atmospheric spectrum. Thistechnique has been successful in detecting various molecules such as H2O, CO,HCN and TiO, as well as several atomic species. Here we present an alternativemethod of performing high-resolution Doppler spectroscopy, using a techniqueknown as Doppler tomography. We present an analysis of HD 179949 b usingDoppler tomography and provide Doppler tomograms confirming previous detectionsof CO at 2.3 microns, and H2O at both 2.3 microns, and 3.5 microns within theatmosphere of HD 179949 b, showing significantly lower background noise levelswhen compared to cross-correlation methods applied to the same data. We alsopresent a novel detection of H2O at 2.1 microns, as well as a tentativedetection of CO on the night side of the planet at 2.3 microns. This representsthe first observational evidence for molecular absorption in the night-sideemission spectrum of an exoplanet using Doppler spectroscopy.