Exoplanets & Exomoons

Cool Gaseous Exoplanets: Surveying The New Frontier With Twinkle

By Keith Cowing
Status Report
February 14, 2024
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Cool Gaseous Exoplanets: Surveying The New Frontier With Twinkle
Forward modelled spectrum for candidate HD 106315 c, binned to R=50 from 0.5-4.5 𝜇m. Molecular absorption components are shown at the binned resolution of the final spectrum. Also shown are the total contributions to the final spectrum from CIA (between H2-H2 and H2-He) and Rayleigh scattering (all atmospheric molecules), with the final spectrum shown in black. — astro-ph.EP

Cool gaseous exoplanets (1.75 R⊕<Rp<3 RJ, 200 K <Teq<1000~K) are an as-yet understudied population, with great potential to expand our understanding of planetary atmospheres and formation mechanisms.

In this paper, we outline the basis for a homogeneous survey of cool gaseous planets with Twinkle, a 0.45-m diameter space telescope with simultaneous spectral coverage from 0.5-4.5~μm, set to launch in 2025.

We find that Twinkle has the potential to characterise the atmospheres of 36 known cool gaseous exoplanets (11~sub-Neptunian, 11~Neptunian, 14~Jovian) at an SNR ≥ 5 during its 3-year primary mission, with the capability of detecting most major molecules predicted by equilibrium chemistry to > 5σ significance. We find that an injected mass-metallicity trend is well-recovered, demonstrating Twinkle’s ability to elucidate this fundamental relationship into cool regime.

We also find Twinkle will be able to detect cloud layers at 3σ or greater in all cool gaseous planets for clouds at ≤ 10 Pa pressure level, but will be insensitive to clouds deeper than 104 Pa in all cases. With these results we demonstrate the capability of the Twinkle mission to greatly expand the current knowledge of cool gaseous planets, enabling key insights and constraints to be obtained for this poorly-charted region of exoplanet parameter space.

Luke Booth, Subhajit Sarkar, Matt Griffin, Billy Edwards

Comments: 14 pages, 6 figures, 6 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2402.06488 [astro-ph.EP] (or arXiv:2402.06488v1 [astro-ph.EP] for this version)
Submission history
From: Luke Booth
[v1] Fri, 9 Feb 2024 15:45:06 UTC (1,006 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) 🖖🏻