Wednesday 20 Sep 2017: Atmospheric library of far away worlds
Mr. Jayesh Goyal - University of Exeter
Physics, 4th Floor 14:00-15:00
The number of exoplanets that have been discovered has now crossed 3500. However, atmospheres of only a few of them have been characterised. Although HST observations have led to the detection of several species like sodium, potassium and water in these atmospheres, it is limited by its wavelength coverage (0.2 to 1.7 microns). The launch of the James Webb Space Telescope (JWST) in 2018 will enable probing exoplanet atmospheres from wavelengths of 0.6 all the way up-to 28 microns. We have created an extensive public library (https://bd-server.astro.ex.ac.uk/exoplanets/) of transmission spectra and atmospheric chemistry of 117 exoplanets using our 1D radiative-convective-chemical equilibrium model ATMO. This library will be extremely valuable for planning future observations and choose scientifically important targets, alongside interpreting current and future observations of exoplanet atmospheres. I will talk about the diversity we encounter in these atmospheres using this library, for a range of planetary characteristics like Temperature, Metallicity, C/O ratio, Haziness and Cloudiness. I will talk about the physical interpretation of observations of 10 exoplanets, including best fit parameters and chi-squared maps. I will discuss about the transition form water to carbon species dominated infrared spectra and how HCN and C2H2 features can be used to constrain the metallicities and C/O ratios of these planets. Finally, I will discuss the limitations of the current library and the near future goals to include P-T profiles, emission spectra, contribution functions and more planets in the library.