1998A&A...334..646H


Query : 1998A&A...334..646H

1998A&A...334..646H - Astronomy and Astrophysics, volume 334, 646-658 (1998/6-2)

Molecular gas in the Galactic center region. III. Probing shocks in molecular cores.

HUETTEMEISTER S., DAHMEN G., MAUERSBERGER R., HENKEL C., WILSON T.L. and MARTIN-PINTADO J.

Abstract (from CDS):

Multiline observations of C18O and SiO isotopomers toward 33 molecular peaks in the Galactic center region, taken at the SEST, JCMT and HHT telescopes, are presented. The C18O presumably traces the total H2 column density, while the SiO traces gas affected by shocks and high temperature chemistry. The J=2-1 line of SiO is seen only in few regions of the Galactic disk. This line is easily detected in all Galactic center sources observed. A comparison of the strength of the rare isotopomers 29SiO and 30SiO to the strength of the main isotopomer 28SiO implies that the J=2 -1 transition of 28SiO is optically thick. The 29Si/30Si isotope ratio of 1.6 in the Galactic center clouds is consistent with the terrestrial value. Large Velocity Gradient models show that the dense component (nH2≥104cm–3) in typical molecular cores in the Galactic center is cool (Tkin≃25K), contrary to what is usually found in Giant Molecular Clouds in the disk, where the densest cores are the hottest. High kinetic temperatures, >100K, known to exist from NH3 studies, are only present at lower gas densities of a few 103cm–3, where SiO is highly subthermally excited. Assuming that C18O traces all of the molecular gas, it is found that in all cases but one, SiO emission is compatible with arising in gas at higher density that is (presently) relatively cool. The relative abundance of SiO is typically 10–9, but differs significantly between individual sources. It shows a dependence on the position of the source within the Galactic center region. High abundances are found in those regions for which bar potential models predict a high likelihood for cloud-cloud collisions. These results can be used to relate the amount of gas that has encountered shocks within the last ∼106 years to the large scale kinematics in the inner ∼500pc of the Galaxy.

Abstract Copyright:

Journal keyword(s): ISM: clouds - ISM: molecules - ISM: structure - Galaxy: center - radio Lines: ISM

Simbad objects: 38

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Number of rows : 38
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 V* AH Sco s*r 17 11 17.0194487616 -32 19 30.714035556   10.03 8.10     M5Ia-Iab 127 0
2 NAME NGC 6334-I Cl* 17 20 53.35 -35 47 01.5           ~ 307 0
3 Bania Clump 1 MoC 17 31 11.6 -33 15 20           ~ 15 1
4 GCM -0.96 +0.13 MoC 17 42 48.3 -29 41 09           ~ 7 0
5 GCM -0.50 -0.03 MoC 17 44 32.5 -29 22 42           ~ 7 0
6 GCM -0.42 -0.01 MoC 17 44 35.2 -29 17 05           ~ 4 0
7 NAME Sgr C MoC 17 44 36.3 -29 28 13           ~ 334 0
8 GCM -0.39 +0.02 MoC 17 44 36.5 -29 15 30           ~ 2 0
9 GCM -0.33 -0.01 MoC 17 44 52.1 -29 13 22           ~ 2 0
10 GCM -0.45 -0.09 MoC 17 44 54.0 -29 31 01           ~ 2 0
11 GCM -0.30 +0.00 MoC 17 44 54.2 -29 11 31           ~ 2 0
12 GCM -0.44 -0.10 MoC 17 44 57.6 -29 21 49           ~ 2 0
13 GCM -0.51 -0.16 MoC 17 45 00.8 -29 27 32           ~ 2 0
14 GCM -0.50 -0.18 MoC 17 45 07.7 -29 27 24           ~ 2 0
15 NAME Sgr A Region reg 17 45 12 -28 48.3           ~ 931 0
16 GCM -0.48 -0.19 MoC 17 45 12.9 -29 26 42           ~ 2 0
17 GCM -0.38 -0.13 MoC 17 45 13.2 -29 19 42           ~ 2 0
18 GCM -0.45 -0.19 MoC 17 45 17.3 -29 25 09           ~ 2 0
19 GCM -0.43 -0.21 MoC 17 45 24.8 -29 24 46           ~ 2 0
20 GCM -0.15 -0.07 MoC 17 45 32.1 -29 06 02           ~ 7 0
21 GCM -0.32 -0.19 MoC 17 45 35.9 -29 18 30           ~ 8 0
22 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 12900 0
23 GCM +0.24 +0.02 MoC 17 46 08.0 -28 43 22           ~ 8 0
24 GCM +0.10 -0.12 MoC 17 46 19.8 -28 54 42           ~ 3 0
25 GCM +0.43 -0.05 MoC 17 46 26.1 -28 32 47           ~ 2 0
26 GCM +0.41 +0.03 MoC 17 46 28.0 -28 34 26           ~ 2 0
27 GCM +0.50 +0.00 MoC 17 46 48.3 -28 30 33           ~ 3 0
28 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 2092 1
29 GCM +0.68 -0.12 MoC 17 47 41.8 -28 25 02           ~ 2 0
30 GAL 000.83-00.18 MoC 17 48 16.6 -28 19 17           ~ 4 0
31 GAL 001.15-00.09 MoC 17 48 40.7 -28 00 00           ~ 2 0
32 NAME Sgr D HII HII 17 48 41.79 -28 01 41.3           ~ 64 1
33 NAME 1.3 Cloud complex MoC 17 49 12.2 -27 52 38           ~ 5 0
34 GCM +0.94 -0.36 MoC 17 49 13.2 -28 19 13           ~ 7 0
35 GCM +3.06 +0.40 MoC 17 51 11.4 -26 06 40           ~ 2 0
36 GCM +3.06 +0.34 MoC 17 51 26.5 -26 08 29           ~ 6 0
37 GCM +2.99 -0.06 MoC 17 52 47.6 -26 24 25           ~ 6 0
38 V* VX Sgr s*r 18 08 04.0442790744 -22 13 26.600899044 11.72 9.41 6.52 3.90 2.11 M8.5Ia 577 0

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2022.05.20-13:28:44

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