TRAPPIST-1 hosts seven transiting Earth-sized exoplanets readily amenable for atmospheric characterization. However, the star is an ultra-cool dwarf and contains its own molecular signatures which can potentially be imprinted on planetary transit lightcurves due to inhomogeneities in the occulted stellar photosphere. We use a new observation of TRAPPIST-1g, the largest planet in the system, together with previous data to disentangle the atmospheric transmission of the planet from that of the star. We use the out-of-transit stellar spectra to reconstruct the stellar flux based on one, two, and three temperature components. We present the results of the stellar reconstructions, along with the geometry of the planetary transit, using physically motivated stellar and planetary spectra to disentangle the signature of the planet and stellar atmospheres. The method presented in the case study of TRAPPIST-1g is widely applicable to all late type M dwarfs with transiting planets and will be important for future characterization studies.
American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019