Proper characterization of the atmospheric composition of super-Earth and sub-Neptune planets will constrain the models that describe the formation and evolution of exoplanetary systems, yet the transition between Earth-mass and Neptune-mass exoplanets is still not well understood. Due to degeneracies between the bulk density and composition of planets in this range, even the basic make-up of many planets is unknown. Transit spectroscopy offers a method to characterize exoplanetary atmospheres and break this compositional degeneracy. We will present preliminary analysis and data reduction techniques for an ongoing large-scale Hubble Space Telescope survey of five planets between 1 and 22 Earth-masses. Using both optical and infrared primary transit spectra from STIS and WFC3, we will measure molecular signatures in the atmospheres of these small, cool planets, as well as any high-altitude clouds and hazes that may dampen such signatures. Results from this investigation will pave the way for future observations of small planets, especially in preparation for the James Webb Space Telescope (JWST) and the Transiting Exoplanet Survey Satellite (TESS).
American Astronomical Society Meeting Abstracts #227
- Pub Date:
- January 2016