Nonhydrostatic Density Profiles of Sodium & Potassium at Close-in Gas Giant Exoplanets
Abstract
With a simple transmission code, we compute high-resolution transit spectra of the sodium/potassium doublet with arbitrary number density profiles as input (in particular non-hydrostatic ones). While hydrostatic atmospheres absorb mostly in an optically thick regime, we find that non-hydrostatic atmospheres (such as escaping atmospheres or exogenic sources) have significant absorption in an optically thin regime. This leads to a distinct shape of non-hydrostatic transit spectra: While such atmospheres are able to absorb as much flux as hydrostatic ones in the line cores, non-hydrostatic atmospheres produce only negligible absorption in the line wings. They furthermore have a D2/D1 line ratio which is close to two (compared to hydrostatic atmospheres where this ratio is close to one). We compare our findings to data from the hot Jupiter WASP-49b. We find that a non-hydrostatic atmosphere (namely an exogenic source) fits the observation significantly better than hydrostatic models. We conclude that current high-resolution observations of the sodium-/potassium doublet might contain signatures of escaping atmspheres or exogenic sources, and that the canonically used hydrostatic number density profile and transit spectra computations based thereon are no longer valid for such non-hydrostatic scenarios.
- Publication:
-
EPSC-DPS Joint Meeting 2019
- Pub Date:
- September 2019
- Bibcode:
- 2019EPSC...13.1795G