Biosignatures & Paleobiology

Molecular Cross Sections for High Resolution Spectroscopy of Super Earths, Warm Neptunes and Hot Jupiters

By Keith Cowing
Press Release
April 9, 2020
Filed under
Molecular Cross Sections for High Resolution Spectroscopy of Super Earths, Warm Neptunes and Hot Jupiters
Molecular cross sections for the volatile species discussed in this work. These are shown at a representative temperature of 1000 K and a pressure of 0.1 bar in the 0.95-5 µm range. The line lists sources for these cross sections are given in Table 1.

High resolution spectroscopy (HRS) has been used to detect a number of species in the atmospheres of hot Jupiters. Key to such detections is accurately and precisely modelled spectra for cross-correlation against the R≳20,000 observations.

There is a need for the latest generation of opacities which form the basis for high signal-to-noise detections using such spectra. In this study we present and make publicly available cross sections for six molecular species, H2O, CO, HCN, CH4, NH3 and CO2 using the latest line lists most suitable for low- and high-resolution spectroscopy. We focus on the infrared (0.95-5~μm) and between 500-1500~K where these species have strong spectral signatures. We generate these cross sections on a grid of pressures and temperatures typical for the photospheres of super Earth, warm Neptunes and hot Jupiters using the latest H2 and He pressure broadening.

We highlight the most prominent infrared spectral features by modelling three representative exoplanets, GJ~1214~b, GJ~3470~b and HD~189733~b, which encompass a wide range in temperature, mass and radii. In addition, we verify the line lists for H2O, CO and HCN with previous high resolution observations of hot Jupiters. However, we are unable to detect CH4 with our new cross sections from HRS observations of HD~102195~b. These high accuracy opacities are critical for atmospheric detections with HRS and will be continually updated as new data becomes available.

Siddharth Gandhi, Matteo Brogi, Sergei N. Yurchenko, Jonathan Tennyson, Phillip A. Coles, Rebecca K. Webb, Jayne L. Birkby, Gloria Guilluy, George A. Hawker, Nikku Madhusudhan, Aldo S. Bonomo, Alessandro Sozzetti
(Submitted on 8 Apr 2020)
Comments: 16 pages, 11 figures, accepted for publication in MNRAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2004.04160 [astro-ph.EP] (or arXiv:2004.04160v1 [astro-ph.EP] for this version)
Submission history
From: Siddharth Gandhi
[v1] Wed, 8 Apr 2020 18:00:00 UTC (1,533 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) 🖖🏻