Understanding the sub-class of ultra hot exoplanets: the MMT Exoplanet Atmosphere SURvEy (MEASURE)

Thursday 5 July, 09:40

High-resolution spectroscopy is a robust and powerful tool in exoplanet characterization. It uses changes in the Doppler shift of a planet to disentangle its spectrum from the glare of its host star. The technique is sensitive to the depth, shape, and position of a planet's spectral lines, and thus reveals information about the planet's composition, atmospheric structure, mass, global wind patterns, and rotation. I will present the first results from MEASURE: the MMT Exoplanet Atmosphere SURvEy. This 40 night survey of 11 planet atmospheres at R~30,000 is the largest homogenous high-resolution survey to date. I will focus on how the survey will provide an accurate measurement of the temperature at which hot Jupiter atmospheres transition into having thermal inversion layers i.e. stratospheres. At high spectral resolution, these features are clearly detected via multiple strong emission lines from e.g. CO, and preliminary results indicate this occurs at hotter temperatures than previously expected. I will discuss the chemical species and processes responsible for this in exoplanet atmospheres and contrast them to the processes occurring in their more massive brown dwarf cousins and cool stars which occupy similar temperature regimes. MEASURE not only provides a homogenous dataset to perform comparative exoplanetology, but provides complementary high-resolution spectra for exoplanets observed with HST and Spitzer, allowing the next step in the detailed characterization of exoplanet atmospheres.

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