ASTRODEBATA / Jon Judež: Can exoplanets wear high-visibility jackets? Prospects and challenges of scattered Lyman alpha light observations

Can exoplanets wear high-visibility jackets? Prospects and challenges of scattered Lyman alpha light observations

Jon Judež
Fakulteta za matematiko in fiziko, UL

Since their first discoveries about 3 decades ago, planets around other stars have risen to become a fast-developing field of its own, where new discoveries challenge our imagination and provide answers to burning questions of our origin. Despite the number of confirmed exoplanets reaching more than 5700, there is only a tiny fraction of them that we are able to observe directly. Vast majority can only be studied by indirect techniques, like transit method, radial velocity, astrometry and gravitational microlensing. We conducted a detailed investigation of the possibility of observing exoplanets directly in scattered Ly alpha light. Recent results for planets in our solar system suggest that planets host vast extended neutral hydrogen atmospheres which are very effective at scattering Ly alpha photons and therefore would make exoplanets much more detectable at this wavelength. In addition, using such observations to study those hydrogen envelopes would help us better constrain the hydrogen escape from planets and therefore shed light on questions of planetary evolution.