Probing the geological setting of exoplanets through atmospheric analysis: using Mars as a test case

Abstract

One of the frontier research fields of exoplanetary science is the study of the composition and variability of exoplanetary atmospheres. This field is now moving from the gas giant planets towards the smaller and colder telluric planets, and future instruments like ANDES will focus on the observations of the atmosphere of telluric planets in the habitable zone in reflected light. These future observations will possibly find variable signals due to the view of different hemispheres of the planet. Particularly, the strength of the signal may be linked to the thickness of the atmospheric layer probed, and therefore to the average altitude variations of the planetary surface, that are related to the global geodynamic evolution of the planet. To better prepare for the interpretation and exploitation of these future data, we used Mars as a Solar System analog of a spatially resolved telluric exoplanet. We observed the reflected light of Mars with the high-resolution near-infrared (NIR) spectrograph GIANO-B (widely used in exoplanetary atmospheric studies) during a 3 month period: we studied the spatial and temporal variations of the Martian CO2 signal using the least-squared deconvolution technique (LSD), to mimic as closely as possible the standard exoplanetary atmospheric analysis. We linked the variations found to the well-known Martian geological surface characteristics: we found a clear dependence of the strength of the CO2 signal with the thickness of the Martian atmospheric layer by comparing the retrieved CO2 signal with the altitudes of our pointings. The proposed strategy is promising: it proved to be effective on Mars and may shed light on the variations in the strength of atmospheric signal of telluric exoplanets.

44 pages, 18 figures, accepted for publication on Icarus

References in corpus (14)

• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• petitRADTRANS: a Python radiative transfer package for exoplanet characterization and retrieval
• Molecfit: A general tool for telluric absorption correction II. Quantitative evaluation on ESO-VLT X-Shooter spectra
• The fast spin-rotation of a young extrasolar planet
• Spectrally resolved detection of sodium in the atmosphere of HD189733b with the HARPS spectrograph
• Five carbon- and nitrogen-bearing species in a hot giant planet's atmosphere
• Discovery of water at high spectral resolution in the atmosphere of 51 Peg b
• Atmospheric Rossiter-McLaughlin effect and transmission spectroscopy of WASP-121b with ESPRESSO
• Neutral Iron Emission Lines From The Day-side Of KELT-9b -- The GAPS Programme With HARPS-N At TNG XX
• On the Occurrence Rate of Hot Jupiters in Different Stellar Environments
• The GAPS Programme at TNG XXXVIII. Five molecules in the atmosphere of the warm giant planet WASP-69b detected at high spectral resolution
• The GAPS Programme at TNG XXXIX -- Multiple molecular species in the atmosphere of the warm giant planet WASP-80 b unveiled at high resolution with GIANO-B
• The GAPS Programme with HARPS-N at TNG. XXXI. The WASP-33 system revisited with HARPS-N
• Martian atmospheric disturbances from orbital images and surface pressure at Jezero Crater, Mars, during Martian Year 36