Imaging & Spectroscopy

YunMa: Enabling Spectral Retrievals of Exoplanetary Clouds

By Keith Cowing
Status Report
January 31, 2023
Filed under , , , , , ,
YunMa: Enabling Spectral Retrievals of Exoplanetary Clouds
Simulated transit spectra of cloudy super-Earths using YunMa. Solid line: total transit depth with all contributions included; dot-dashed line: water ice clouds; faint-dotted line: water vapour. Blue, green and red lines: H2/He dominated, cloudy atmospheres with different pc (see legend). Purple and yellow lines: heavier cloudy atmospheres with 50% N2. — astro-ph.EP

In this paper, we present YunMa, a model which enables the study of cloud microphysics and radiative properties in exoplanetary atmospheres.

YunMa simulates the vertical distribution and sizes of cloud particles and their corresponding scattering signature in transit spectra. We validated YunMa against results from the literature.

When coupled to the TauREx 3 platform, an open Bayesian framework for spectral retrievals, YunMa enables the retrieval of the cloud properties and parameters from transit spectra of exoplanets. The sedimentation efficiency (fsed), which controls the cloud microphysics, is set as a free parameter in retrievals. We assess the retrieval performances of YunMa through 28 instances of a cloudy super-Earth’s atmosphere. This work also highlights the need for cloud radiative transfer and microphysics modelling to retrieve next-generation data of exoplanets.

Sketch of the A-M micophysical approach adopted in YunMa. Cloud particles may form when the mixing ratio of the condensable gas exceeds the saturation mixing ratio, which is derived from its saturation vapour pressure (SVP). The vertical distribution of the cloud particle sizes (VDCP) is derived from the balance between the sedimentation of the cloud particles and the atmospheric turbulent mixing.

Sushuang Ma, Yuichi Ito, Ahmed Faris Al-Refaie, Quentin Changeat, Billy Edwards, Giovanna Tinetti

Comments: 24 pages, 12 figures, submitted to ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2301.13708 [astro-ph.EP] (or arXiv:2301.13708v1 [astro-ph.EP] for this version)
Submission history
From: Sushuang Ma
[v1] Tue, 31 Jan 2023 15:35:37 UTC (3,387 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) 🖖🏻