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Changes in Atmospheric Chemistry over the Habitable Zone for Earthlike Planets Orbiting Main Sequence Stars

Grenfell, John Lee (2006) Changes in Atmospheric Chemistry over the Habitable Zone for Earthlike Planets Orbiting Main Sequence Stars. 4th Planetary Formation Workshop, 2006-03-01 - 2006-03-03, Heidelberg, Germany.

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Kurzfassung

We have used a coupled radiative-convective photochemical column model to calculate changes in atmospheric biomarkers on a planet having Earth's composition which we situated at the inner, mid, and outer Habitable Zone (HZ) for a solar, F2V and K2V star. The HZ was defined conservatively to be suitable for humans i.e. 0°C &lt; T <sub>surface</sub> &lt; 30°C which led to the model calculating a narrow HZ width of (0.95-1.09) Astronomical Units (AU) for the solar-type star, (1.59-1.80) AU for the F2V star and (0.51-0.59) AU for the K2V star. Despite the narrowness of the HZ the biomarkers H<sub>2</sub>O, CH<sub>4</sub> and CH<sub>3</sub>Cl varied by large amounts across the solar HZ, for example. Whereas H<sub>2</sub>O decreased moving outwards across the HZ due to enhanced condensation in the troposphere, CH<sub>4</sub> and CH<sub>3</sub>Cl increased associated with a slowing in H<sub>2</sub>O+O<sup>1</sup>D --&gt; 2OH, hence less OH, an important sink for these two compounds. Ozone changes were smaller across the HZ. A source-sink analysis suggested the important process was a slowing in the O<sub>3</sub>+hv sink. We also considered changes in species which impact ozone – the so-called family species (and their reservoirs) which can catalytically destroy ozone. HCl, for example is a chlorine reservoir (storage) molecule, which increased by a factor 5-10 on moving outwards over the solar HZ. For the F2V and K2V stars, similar sources and sinks dominated the chemical biomarker budget as for the solar case and columns trends were comparable across the HZ. Ratios of biomarkers are easier to detect than are absolute concentrations. Our results imply that ratios such as (O<sub>3</sub>/H<sub>2</sub>O) and (CH<sub>4</sub>/H<sub>2</sub>O) can vary by large amounts and still be consistent with habitability, even for a conservatively-defined HZ.

elib-URL des Eintrags:https://elib.dlr.de/22598/
Dokumentart:Konferenzbeitrag (Vortrag)
Titel:Changes in Atmospheric Chemistry over the Habitable Zone for Earthlike Planets Orbiting Main Sequence Stars
Autoren:
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID-iDORCID Put Code
Grenfell, John LeeNICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Datum:2006
Referierte Publikation:Nein
Open Access:Nein
Gold Open Access:Nein
In SCOPUS:Nein
In ISI Web of Science:Nein
Stichwörter:Habitable Zone, Exoplanets, Biomarkers
Veranstaltungstitel:4th Planetary Formation Workshop
Veranstaltungsort:Heidelberg, Germany
Veranstaltungsart:internationale Konferenz
Veranstaltungsdatum:2006-03-01 - 2006-03-03
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W EW - Erforschung des Weltraums
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W EW - Erforschung des Weltraums
DLR - Teilgebiet (Projekt, Vorhaben):W - Vorhaben Extrasolare Planeten (alt)
Standort: Berlin-Adlershof
Institute & Einrichtungen:Institut für Planetenforschung > Extrasolare Planeten und Atmosphären
Hinterlegt von: Hedelt, Pascal
Hinterlegt am:08 Mär 2006
Letzte Änderung:14 Jan 2010 21:00

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