Exoplanets & Exomoons

Expanding The Inventory Of Spectral Lines Used To Trace Atmospheric Escape In Exoplanets

By Keith Cowing
Status Report
June 14, 2023
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Expanding The Inventory Of Spectral Lines Used To Trace Atmospheric Escape In Exoplanets
Transmission spectrum of the hot Jupiter planet around a G2 star, for a Parker wind profile with M˙ = 1010 g s−1 and T = 8000 K. The strongest line of each atomic/ionic species is marked if it exceeds our thresholds of 1% at λ < 4000 Å and 0.1% at λ > 4000 Å and its line-forming radius is shown in the top right panel of Fig. 3. — astro-ph.EP

Escaping exoplanet atmospheres have been observed as deep transit signatures in a few specific spectral lines. Detections have been made in the hydrogen Ly-α 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.

Dion Linssen, Antonija Oklopčić

Comments: Accepted for publication in A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2306.06971 [astro-ph.EP] (or arXiv:2306.06971v1 [astro-ph.EP] for this version)
Submission history
From: Dion Linssen
[v1] Mon, 12 Jun 2023 09:03:50 UTC (3,842 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻