Spitzer IRS observations of Titan as a precursor to JWST MIRI observations

Journal article

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; 5.13–14.29 μm, R ∼ 60–127) and short wavelength–high resolution (SH; 9.89–19.51 μm, R ∼ 600) channels 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 16.35–19.35 μm wavelength range observed by the SH channel but impacted by higher noise levels in the CIRS observations. We use the SH data to provide estimated haze extinction cross sections for the 16.67–17.54 μm range that are missing in previous studies. We conclude by identifying spectral features in the 16.35–19.35 μm wavelength range that could be analyzed further through upcoming James Webb Space Telescope Cycle 1 observations with the Mid-Infrared Instrument (5.0–28.3 μm, R ∼ 1500–3500). We also highlight gaps in the 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.

Authors: Coy, BP; Nixon, CA; Rowe-Gurney, N; Achterberg, R; Lombardo, NA

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IOP Publishing
• Journal: The Planetary Science Journal
• Volume: 4
• Issue: 6
• Article number: 114
• Publication date: 2023-06-27
• Acceptance date: 2023-04-26
• DOI: 10.3847/PSJ/acd10f
• EISSN: 2632-3338
• Language: English
• Keywords: radiative transfer; FFR; atmospheric composition; Saturnian satellites; Titan; infrared astronomy; natural satellite atmospheres; transmission spectroscopy
• Subjects: Physical sciences; Space sciences