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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 709848.0, MPI für Astronomie / Publikationen_mpia
Infrared H3+ and CO studies of the Galactic core: GCIRS 3 and GCIRS 1W
Authors:Goto, M.; Geballe, T. R.; Indriolo, N.; Yusef-Zadeh, F.; Usuda, T.; Henning, T.; Oka, T.
Date of Publication (YYYY-MM-DD):2014
Title of Journal:The Astrophysical Journal
Issue / Number:2
Start Page:id. 96 (15 pp)
Audience:Not Specified
Abstract / Description:We have obtained improved spectra of key fundamental band lines of H_3^+, R(1, 1) l , R(3, 3) l , and R(2, 2) l , and ro-vibrational transitions of CO on sightlines toward the luminous infrared sources GCIRS 3 and GCIRS 1W, each located in the Central Cluster of the Galactic center within several arcseconds of Sgr A*. The spectra reveal absorption occurring in three kinds of gaseous environments: (1) cold dense and diffuse gas associated with foreground spiral/lateral arms; (2) warm and diffuse gas absorbing over a wide and mostly negative velocity range, which appears to fill a significant fraction of the Galaxy's Central Molecular Zone (CMZ); and (3) warm, dense and compact clouds with velocities near +50 km s-1 probably within 1-2 pc of the center. The absorptions by the first two cloud types are nearly identical for all the sources in the Central Cluster, and are similar to those previously observed on sightlines from Sgr A* to 30 pc east of it. Cloud type (3), which has only been observed toward the Central Cluster, shows distinct differences between the sightlines to GCIRS 3 and GCIRS 1W, which are separated on the sky by only 0.33 pc in projection. We identify this material as part of an inward extension of the circumnuclear disk previously known from HCN mapping. Lower limits on the products of the hydrogen ionization rate zeta and the path length L are 2.3 × 105 cm s-1 and 1.5 × 103 cm s-1 for the warm and diffuse CMZ gas and for the warm and dense clouds in the core, respectively. The limits indicate that the ionization rates in these regions are well above 10-15 s-1. Based on data collected during the CRIRES Science Verification program (60.7A-9057) and open time program (079.C-0874) at the VLT on Cerro Paranal (Chile), which is operated by the European Southern Observatory (ESO). Based also on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based on data obtained from the ESO Science Archive Facility under request number MGOTO 43308.
Free Keywords:Galaxy: center; ISM: clouds; ISM: lines and bands; ISM: molecules; stars: individual: GCIRS 1W GCIRS 3
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-637X %R 10.1088/0004-637X/786/2/96
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