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Proxima Centauri b: A Strong Case for Including Cosmic-Ray-induced Chemistry in Atmospheric Biosignature Studies

Scheucher, M. and Herbst, K and Schmidt, V and Grenfell, John Lee and Schreier, Franz and Banjac, S and Heber, B and Rauer, H and Sinnhuber, M (2020) Proxima Centauri b: A Strong Case for Including Cosmic-Ray-induced Chemistry in Atmospheric Biosignature Studies. Astrophysical Journal, 893 (12), pp. 1-7. Institute of Physics (IOP) Publishing. doi: 10.3847/1538-4357/ab7b74. ISSN 0004-637X.

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Official URL: https://iopscience.iop.org/article/10.3847/1538-4357/ab7b74


Due to its Earth-like minimum mass of 1.27 M E and its close proximity to our solar system, Proxima Centauri b is one of the most interesting exoplanets for habitability studies. Its host star, Proxima Centauri, is however a strongly flaring star, which is expected to provide a very hostile environment for potentially habitable planets. We perform a habitability study of Proxima Centauri b assuming an Earth-like atmosphere under high stellar particle bombardment, with a focus on spectral transmission features. We employ our extensive model suite calculating energy spectra of stellar particles, their journey through the planetary magnetosphere, ionosphere, and atmosphere, ultimately providing planetary climate and spectral characteristics, as outlined in Herbst et al. Our results suggest that together with the incident stellar energy flux, high particle influxes can lead to efficient heating of the planet well into temperate climates, by limiting CH4 amounts, which would otherwise run into antigreenhouse for such planets around M stars. We identify some key spectral features relevant for future spectral observations: First, NO2 becomes the major absorber in the visible, which greatly impacts the Rayleigh slope. Second, H2O features can be masked by CH4 (near-infrared) and CO2 (mid- to far-infrared), making them nondetectable in transmission. Third, O3 is destroyed and instead HNO3 features become clearly visible in the mid- to far-infrared. Lastly, assuming a few percent of CO2 in the atmosphere, CO2 absorption at 5.3 μm becomes significant (for flare and nonflare cases), strongly overlapping with a flare related NO feature in Earth's atmosphere.

Item URL in elib:https://elib.dlr.de/137307/
Document Type:Article
Title:Proxima Centauri b: A Strong Case for Including Cosmic-Ray-induced Chemistry in Atmospheric Biosignature Studies
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Scheucher, M.markus.scheucher (at) dlr.deUNSPECIFIED
Herbst, KInstitut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, Kiel, GermanyUNSPECIFIED
Schmidt, VUni. KielUNSPECIFIED
Grenfell, John LeeLee.Grenfell (at) dlr.deUNSPECIFIED
Schreier, FranzFranz.Schreier (at) dlr.dehttps://orcid.org/0000-0001-7196-6599
Banjac, SChristian-Albrechts- Uni. zu KielUNSPECIFIED
Heber, BChristian-Albrechts- Uni. zu KielUNSPECIFIED
Rauer, Hheike.rauer (at) dlr.deUNSPECIFIED
Sinnhuber, MKarlsruhe Institute of Technology (KIT), Karlsruhe, GermanyUNSPECIFIED
Date:10 April 2020
Journal or Publication Title:Astrophysical Journal
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.3847/1538-4357/ab7b74
Page Range:pp. 1-7
Publisher:Institute of Physics (IOP) Publishing
Keywords:exoplanets; atmospheric; cosmic rays; composition
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Vorhaben Planetary Evolution and Life (old)
Location: Berlin-Adlershof , Oberpfaffenhofen
Institutes and Institutions:Institute of Planetary Research > Extrasolar Planets and Atmospheres
Institute of Planetary Research > Leitungsbereich PF
Remote Sensing Technology Institute > Atmospheric Processors
Deposited By: Grenfell, John Lee
Deposited On:09 Nov 2020 15:30
Last Modified:10 Nov 2020 16:05

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