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Spectral features of Earth-like planets and their detectability at different orbital distances around F, G, and K-type stars

Hedelt, Pascal and von Paris, Philip and Godolt, Mareike and Gebauer, Stefanie and Grenfell, John Lee and Rauer, Heike and Schreier, Franz and Selsis, Franck and Trautmann, Thomas (2013) Spectral features of Earth-like planets and their detectability at different orbital distances around F, G, and K-type stars. Astronomy & Astrophysics, 553, pp. 1-14. EDP Sciences. doi: 10.1051/0004-6361/201117723. ISSN 0004-6361.

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Context. In recent years, more and more transiting terrestrial extrasolar planets have been found. Spectroscopy already yielded the detection of molecular absorption bands in the atmospheres of Jupiter and Neptune-sized exoplanets. Detecting spectral features in the atmosphere of terrestrial planets is the next great challenge for exoplanet characterization. Aims. We investigate the spectral appearance of Earth-like exoplanets in the habitable zone of different main sequence (F, G, and K-type) stars at different orbital distances. We furthermore discuss for which of these scenarios biomarker absorption bands and related compounds may be detected during primary or secondary transit with near-future telescopes and instruments. Methods. Atmospheric profiles from a 1D cloud-free atmospheric climate-photochemistry model were used to compute primary and secondary eclipse infrared spectra. The spectra were analyzed taking into account different filter bandpasses of two photometric instruments planned to be mounted to the James Webb Space Telescope (JWST). We analyzed in which filters and for which scenarios molecular absorption bands are detectable when using the space-borne JWST or the ground-based telescope European Extremely Large Telescope (E-ELT). Results. Absorption bands of carbon dioxide (CO2 ), water (H2 O), methane (CH4 ) and ozone (O3 ) are clearly visible in both high-resolution spectra as well as in the filters of photometric instruments. However, only during primary eclipse absorption bands of CO2 , H2 O and O3 are detectable for all scenarios when using photometric instruments and an E-ELT-like telescope setup. CH4 is only detectable at the outer HZ of the K-type star since here the atmospheric modeling results in very high abundances. Since the detectable CO2 and H2 O absorption bands overlap, separate bands need to be observed to prove their existence in the planetary atmosphere. In order to detect H2 O in a separate band, a S/N of S /N > 7 needs to be achieved for E-ELT observations, e.g. by co-adding at least 10 transit observations. Using a space-borne telescope like the JWST enables the detection of CO2 at 4.3 μm, which is not possible for ground-based observations due to the Earth’s atmospheric absorption. Hence combining observations of space-borne and ground-based telescopes might allow to detect the presence of the biomarker molecule O3 and the related compounds H2O and CO2 in a planetary atmosphere. Other absorption bands using the JWST can only be detected for much higher S/Ns, which is not achievable by just co-adding transit observations since this would be far beyond the planned mission time of JWST.

Item URL in elib:https://elib.dlr.de/82256/
Document Type:Article
Title:Spectral features of Earth-like planets and their detectability at different orbital distances around F, G, and K-type stars
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Gebauer, StefanieTU Berlin, Institut für Astronomie und AstrophysikUNSPECIFIEDUNSPECIFIED
Grenfell, John LeeTU Berlin, Institut für Astronomie und AstrophysikUNSPECIFIEDUNSPECIFIED
Schreier, FranzUNSPECIFIEDhttps://orcid.org/0000-0001-7196-6599UNSPECIFIED
Selsis, FranckLaboratoire d'Astrophysique de Bordeaux, FrankreichUNSPECIFIEDUNSPECIFIED
Date:May 2013
Journal or Publication Title:Astronomy & Astrophysics
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 1-14
Publisher:EDP Sciences
Series Name:EDP Sciences
Keywords:Exoplanets, Habitability, Spectroscopy, Photometry, Charactrerization, E-ELT, JWST
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Vorhaben Entwicklung von Atmosphärenprozessoren (old)
Location: Berlin-Adlershof , Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Atmospheric Processors
Institute of Planetary Research > Extrasolar Planets and Atmospheres
Deposited By: Hedelt, Pascal
Deposited On:06 May 2013 13:17
Last Modified:14 Nov 2023 13:18

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