Universität zu Köln

Moultaka, J., Eckart, A., Tikare, K. and Bajat, A. (2019). High-spectral resolution M-band observations of CO Rot-Vib absorption lines towards the Galactic center. Astron. Astrophys., 626. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. In the near- to mid-infrared wavelength domain, bright continuum sources in the central parsec of the Galactic center (GC) are subject to foreground absorption. These sources therefore represent ideal probes of the intervening material that is responsible for the absorption along the line of sight. Aims. Our aim is to shed light on the location and physics of the absorbing clouds. We try to find out which of the gaseous absorbing materials is intimately associated with the GC and which one is associated with clouds at a much larger distance. Methods. We used the capabilities of CRIRES spectrograph located at ESO Very Large Telescope in Chile to obtain absorption spectra of individual lines at a high spectral resolution of R = 50 000, that is, 5 km s(-1). We observed the (CO)-C-12 R(0), P(1), P(2), P(3), P(4), P(5), P(6), P(7) and P(9) transition lines, applied standard data reduction, and compared the results with literature data. Results. We present the results of CRIRES observations of 13 infrared sources located in the central parsec of the Galaxy. The data provide direct evidence for a complex structure of the interstellar medium along the line of sight and in the close environment of the central sources. In particular we find four cold foreground clouds at radial velocities VLSR of the order of -145, -85, -60, and -40 +/- 15 km s(-1) that show absorption in the lower transition lines from R(0) to P(2) and in all the observed spectra. We also find in all sources an absorption in velocity range of 50-60 km s(-1), possibly associated with the so-called 50 km s(-1) cloud and suggesting an extension of this cloud in front of the GC. Finally, we detect individual absorption lines that are probably associated with material much closer to the center and with the sources themselves, suggesting the presence of cold gas in the local region.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Moultaka, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Eckart, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tikare, K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bajat, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-137964
DOI:	10.1051/0004-6361/201935102
Journal or Publication Title:	Astron. Astrophys.
Volume:	626
Date:	2019
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 DUST-EMBEDDED SOURCES; OF-SIGHT; FORMALDEHYDE ABSORPTION; APERTURE SYNTHESIS; RADIAL-VELOCITIES; STELLAR DYNAMICS; PROPER MOTIONS; CENTRAL PARSEC; NORTHERN ARM; GASEOUS CO Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/13796