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Detectability of biosignatures on LHS 1140 b

Wunderlich, Fabian and Scheucher, Markus and Grenfell, John Lee and Schreier, Franz and Sousa-Silva, Clara and Godolt, Mareike and Rauer, Heike (2021) Detectability of biosignatures on LHS 1140 b. Astronomy & Astrophysics, 647 (A48), pp. 1-19. EDP Sciences. doi: 10.1051/0004-6361/202039663. ISSN 0004-6361.

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Official URL: https://www.aanda.org/articles/aa/abs/2021/03/aa39663-20/aa39663-20.html

Abstract

Context. Terrestrial extrasolar planets around low-mass stars are prime targets when searching for atmospheric biosignatures with current and near-future telescopes. The habitable-zone super-Earth LHS 1140 b could hold a hydrogen-dominated atmosphere, and is an excellent candidate for detecting atmospheric features. Aims. In this study we investigate how the instellation and planetary parameters influence the atmospheric climate, chemistry, and spectral appearance of LHS 1140 b. We study the detectability of selected molecules, in particular potential biosignatures, with the upcoming James Webb Space Telescope (JWST) and Extremely Large Telescope (ELT). Methods. In the first step we used the coupled climate–chemistry model 1D-TERRA to simulate a range of assumed atmospheric chemical compositions dominated by molecular hydrogen (H2) and carbon dioxide (CO2). In addition, we varied the concentrations of methane (CH4) by several orders of magnitude. In the second step we calculated transmission spectra of the simulated atmospheres and compared them to recent transit observations. Finally, we determined the observation time required to detect spectral bands with low-resolution spectroscopy using JWST, and the cross-correlation technique using ELT. Results. In H2-dominated and CH4-rich atmospheres oxygen (O2) has strong chemical sinks, leading to low concentrations of O2 and ozone (O3). The potential biosignatures ammonia (NH3), phosphine (PH3), chloromethane (CH3Cl), and nitrous oxide (N2O) are less sensitive to the concentration of H2, CO2, and CH4 in the atmosphere. In the simulated H2-dominated atmosphere the detection of these gases might be feasible within 20 to 100 observation hours with ELT or JWST when assuming weak extinction by hazes. Conclusions. If further observations of LHS 1140 b suggest a thin, clear, hydrogen-dominated atmosphere, the planet would be one of the best known targets to detect biosignature gases in the atmosphere of a habitable-zone rocky exoplanet with upcoming telescopes.

Item URL in elib:https://elib.dlr.de/142429/
Document Type:Article
Title:Detectability of biosignatures on LHS 1140 b
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Wunderlich, Fabianfabian.wunderlich (at) dlr.dehttps://orcid.org/0000-0002-2238-5269
Scheucher, Markusmarkus.scheucher (at) dlr.deUNSPECIFIED
Grenfell, John LeeLee.Grenfell (at) dlr.dehttps://orcid.org/0000-0003-3646-5339
Schreier, FranzFranz.Schreier (at) dlr.dehttps://orcid.org/0000-0001-7196-6599
Sousa-Silva, ClaraCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USAUNSPECIFIED
Godolt, MareikeMareike.Godolt (at) dlr.deUNSPECIFIED
Rauer, Heikeheike.rauer (at) dlr.deUNSPECIFIED
Date:March 2021
Journal or Publication Title:Astronomy & Astrophysics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:647
DOI :10.1051/0004-6361/202039663
Page Range:pp. 1-19
Publisher:EDP Sciences
ISSN:0004-6361
Status:Published
Keywords:planets and satellites: terrestrial planets / planets and satellites: detection / planets and satellites: composition / planets and satellites: atmospheres / techniques: spectroscopic / astrochemistry
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 - Planetary Evolution and Life, R - Spectroscopic methods of the atmosphere
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:31 May 2021 16:23
Last Modified:09 Jun 2021 07:42

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