Spitzer IRS Observations of Titan as a Precursor to JWST MIRI Observations

In this work we present, for the first time, infrared spectra of Titan from the Spitzer Space Telescope (2004−2009).

The data are from both the short wavelength-low resolution (SL, 5.13−14.29μm,R∼60−127) and short wavelength-high resolution channels (SH, 9.89−19.51μm,R∼600) showing the emissions of CH4, C2H2, C2H4, C2H6, C3H4, C3H6, C3H8, C4H2, HCN, HC3N, and CO2. We compare the results obtained for Titan from Spitzer to those of the Cassini Composite Infrared Spectrometer (CIRS) for the same time period, focusing on the 16.35−19.35μm wavelength range observed by the SH channel but impacted by higher noise levels in CIRS observations. We use the SH data to provide estimated haze extinction cross-sections for the 16.67−17.54μm range that are missing in previous studies.

We conclude by identifying spectral features in the 16.35−19.35μm wavelength range, including two prominent emission features at 16.39 and 17.35μm, that could be analyzed further through upcoming James Webb Space Telescope Cycle 1 observations with the Mid-Infrared Instrument (5.0−28.3μm,R∼1500−3500). We also highlight gaps in current spectroscopic knowledge of molecular bands, including candidate trace species such as C60 and detected trace species such as C3H6, that could be addressed by theoretical and laboratory study.

Brandon Park Coy, Conor A. Nixon, Naomi Rowe-Gurney, Richard Achterberg, Nicholas A. Lombardo, Leigh N. Fletcher, Patrick Irwin

Comments: Accepted to Planetary Science Journal April 28, 2023Subjects: Earth and Planetary Astrophysics (astro-ph.EP)Cite as: arXiv:2305.13234 [astro-ph.EP] (or arXiv:2305.13234v1 [astro-ph.EP] for this version)Submission historyFrom: Brandon Park Coy[v1] Mon, 22 May 2023 17:06:27 UTC (707 KB)https://arxiv.org/abs/2305.13234

Astrobiology

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