Universität zu Köln

Rezac, L., Hartogh, P., Guesten, R., Wiesemeyer, H., Huebers, H. -W., Jarchow, C., Richter, H., Klein, B. and Honingh, N. (2015). First detection of the 63 mu m atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA. Astron. Astrophys., 580. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. The Stratospheric Observatory for Infrared Astronomy (SOFIA) with its 2.5 m telescope provides new science opportunities for spectroscopic observations of planetary atmospheres in the far-infrared wavelength range. Aims. This paper presents first results from the 14 May, 2014 observing campaign of the Martian atmosphere at 4.7 THz using the German REceiver for Astronomy at Terahertz frequencies (GREAT) instrument. Methods. The atomic oxygen 63 mu m transition, OI, was detected in absorption against the Mars continuum, with a high signal-to-noise ratio (similar to 35). A beam-averaged atomic oxygen from a global circulation model was used as input to the radiative transfer simulations of the observed line area and to obtain a new estimate on the column density using a grid-search method. Results. Minimizing differences between the calculated and observed line intensities in the least-square sense yields an atomic oxygen column density of (1.1 +/- 0.2) x 10(17) cm(2). This value is about twice as low as predicted by a modern photochemical model of Mars. The radiative transfer simulations indicate that the line forms in the upper atmospheric region over a rather extended altitude region of 70-120 km. Conclusions. For the first time, a far-infrared transition of the atomic oxygen line was detected in the atmosphere of Mars. The absorption depth provides an estimate on the column density, and this measurement provides additional means to constrain the photochemical models in global circulation models and airglow studies. The lack of other means for monitoring the atomic oxygen in the Martian upper atmosphere makes future observations with the SOFIA observatory highly desirable.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Rezac, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hartogh, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Guesten, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wiesemeyer, H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Huebers, H. -W. UNSPECIFIED UNSPECIFIED UNSPECIFIED Jarchow, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Richter, H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Klein, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Honingh, N. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-397201
DOI:	10.1051/0004-6361/201526377
Journal or Publication Title:	Astron. Astrophys.
Volume:	580
Date:	2015
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MARTIAN ATMOSPHERE; SPECTROMETER Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/39720