Expanding the inventory of spectral lines used to trace atmospheric escape in exoplanets

Abstract

Escaping exoplanet atmospheres have been observed as deep transit signatures in a few specific spectral lines. Detections have been made in the hydrogen Ly-$\alpha$ line, the metastable helium line at 10830 Å and some UV lines of metallic species. Observational challenges, unexpected non-detections and model degeneracies have generally made it difficult to draw definitive conclusions about the escape process for individual planets. Expanding on the suite of spectral tracers used may help to mitigate these challenges. We present a new framework for modeling the transmission spectrum of hydrodynamically escaping atmospheres. We predict FUV to NIR spectra for systems with different planet and stellar types and identify new lines that can potentially be used to study their upper atmospheres. Measuring the radius in the atmosphere at which the strongest lines form puts them into context within the upper atmospheric structure. Targeting a set of complementary spectral lines for the same planet will help us to better constrain the outflow properties.

Accepted for publication in A&A

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Cited by in corpus (6)

• The open-source sunbather code: modeling escaping planetary atmospheres and their transit spectra
• Using the helium triplet as a tracer of the physics of giant planet outflows
• sunset: A database of synthetic atmospheric-escape transmission spectra for nearly every transiting planet
• A new pathway to SO${}_2$: Revealing the NUV driven sulfur chemistry in hot gas giants
• A theory of transmission spectroscopy of hydrodynamic outflows from planetary atmospheres: Spectral-line saturation and limits on mass-loss constraints
• Probing the extent of WASP-52 b's atmosphere. High-resolution observations and 3D modeling insights