2019ApJ...883...54O


Query : 2019ApJ...883...54O

2019ApJ...883...54O - Astrophys. J., 883, 54-54 (2019/September-3)

The central 300 pc of the Galaxy probed by infrared spectra of H3+ and CO. I. Predominance of Warm and diffuse gas and high H2 ionization rate.

OKA T., GEBALLE T.R., GOTO M., USUDA T., McCALL B.J. and INDRIOLO N.

Abstract (from CDS):

The molecular gas in the central molecular zone (CMZ) of the Galaxy has been studied using infrared absorption spectra of H3+ lines at 3.5-4.0 µm and CO lines near 2.34 µm. In addition to the previously reported spectra of these lines toward eight stars located within 30 pc of Sgr A*, there are now spectra toward ∼30 bright stars located from 140 pc west to 120 pc east of Sgr A*. The spectra show the presence of warm (T ∼ 200 K) and diffuse (n < 100 cm–3) gas with N(H3+) ∼ 3 x 1015 cm–2 on the majority of sight lines. Instead of our previous analysis, in which only electrons from photoionization of carbon atoms were considered, we have developed a simple model calculation in which the cosmic-ray ionization of H2 and H is also taken into account. We conclude the following: (1) Warm and diffuse gas dominates the volume of the CMZ. The volume filling factor of dense gas must be much less than 0.1, and the CMZ is not as opaque as previously considered. The X-ray-emitting ultrahot 108 K plasma, which some thought to dominate the CMZ, does not exist over extended regions. (2) The cosmic-ray ionization rate is ζ ∼ 2 x 10–14 s–1, higher than in Galactic dense clouds and diffuse clouds by factors of ∼1000 and ∼100, respectively. If the equipartition law stands, this suggests a pervading magnetic field on the order of ∼100 µG.

Abstract Copyright: © 2019. The American Astronomical Society. All rights reserved.

Journal keyword(s): astrochemistry - cosmic rays - Galaxy: center - infrared: stars - ISM: lines and bands - ISM: molecules

Simbad objects: 58

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Number of rows : 58
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 M 77 GiP 02 42 40.771 -00 00 47.84 9.70 9.61 8.87 10.1 9.9 ~ 4224 2
2 * zet Per V* 03 54 07.9224751 +31 53 01.081262 2.19 2.97 2.85 2.71 2.62 B1Ib 821 0
3 V* X Per HXB 03 55 23.0778791365 +31 02 45.045745259 6.090 6.840 6.720     O9.5III 923 0
4 NAME Nor Arm PoG 16 00 -50.0           ~ 359 0
5 NAME Sgr E Rad 17 42 38 -29 48.2           ~ 46 0
6 2MASS J17432173-2951430 * 17 43 21.732 -29 51 43.04           ~ 7 0
7 2MASS J17432823-2952159 * 17 43 28.23456 -29 52 15.9456           ~ 3 0
8 IRAS 17403-2948 * 17 43 29.88168 -29 50 07.4040           ~ 7 0
9 NAME Sgr C MoC 17 44 36.3 -29 28 13           ~ 325 0
10 2MASS J17443734-2927557 NIR 17 44 37.34688 -29 27 55.7532           ~ 3 0
11 2MASS J17444083-2926550 * 17 44 40.83456 -29 26 55.0536           ~ 4 0
12 2MASS J17445895-2923259 Mi? 17 44 58.95288 -29 23 25.9008           ~ 2 0
13 ISOGAL-P J174504.9-291146 Y*? 17 45 04.837 -29 11 46.48           ~ 11 0
14 NAME Sgr A Region reg 17 45 12 -28 48.3           ~ 924 0
15 2MASS J17451618-2903156 WR* 17 45 16.1745721242 -29 03 15.693520110       22.31   Ofpe/WN9 17 0
16 GCM -0.13 -0.08 MoC 17 45 25.2 -29 05 30           ~ 113 1
17 NAME Sgr A H2 HII 17 45 28.61832 -28 56 04.9956           ~ 5 0
18 NAME Galactic Center gam 17 45 39.60213 -29 00 22.0000           ~ 12306 0
19 GCIRS 3 * 17 45 39.80 -29 00 23.9           ~ 142 0
20 GCIRS 16 Cl* 17 45 40.0 -29 00 28           ~ 320 0
21 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 3684 3
22 GCIRS 8 * 17 45 40.14 -28 59 58.7           O 72 0
23 GCIRS 21 WR* 17 45 40.222 -29 00 30.85           WC9 95 0
24 GCIRS 16NE WR* 17 45 40.26 -29 00 27.2           Ofpe/WN9 143 0
25 GCIRS 1W Em* 17 45 40.442 -29 00 27.51           Be? 99 0
26 GCIRS 10W * 17 45 40.5305 -29 00 23.001           ~ 45 0
27 AGAL G000.163+00.079 smm 17 45 42 -28 45.3           ~ 11 0
28 GCM -0.02 -0.07 MoC 17 45 50.4 -28 59 06           ~ 151 0
29 NAME Arches Cluster Cl* 17 45 50.5 -28 49 28           ~ 665 0
30 2MASS J17460215-2857235 * 17 46 02.15928 -28 57 23.5188           ~ 4 0
31 2MASS J17460433-2852492 NIR 17 46 04.33992 -28 52 49.2888           ~ 8 0
32 [NHS93] 22 WR* 17 46 05.625 -28 51 31.92           WN5b 25 0
33 BGPS G000.262+00.027 mm 17 46 08.2061 -28 41 53.749           ~ 4 0
34 2MASS J17460825-2849545 NIR 17 46 08.25120 -28 49 54.5628           ~ 8 0
35 [VB99] M0.25+0.01 P5 smm 17 46 10.3421 -28 42 44.541           ~ 6 0
36 NAME Quintuplet Cluster OpC 17 46 13.9 -28 49 48           ~ 474 0
37 LHO 75 WR* 17 46 14.11 -28 49 36.7           WC9?d 22 0
38 WR 102dc WR* 17 46 14.69 -28 49 40.7           WC9d+OB 51 0
39 LHO 84 WR* 17 46 14.77 -28 49 34.2           WC9d 27 0
40 [FMM95] 3 s*b 17 46 15.240 -28 50 03.58           LBV 142 1
41 WR 102ha WR* 17 46 15.86544 -28 49 45.6312           WC8/9d+OB 55 0
42 CXOGC J174617.7-285007 * 17 46 17.831 -28 50 07.47           ~ 10 0
43 [GMC99] D6 s*b 17 46 17.982 -28 49 03.46           LBV 59 0
44 2MASS J17463219-2844546 * 17 46 32.19864 -28 44 54.6252           ~ 4 0
45 MMB G000.475-00.010 Mas 17 46 47.07 -28 32 06.9           ~ 15 0
46 2MASS J17470137-2813006 * 17 47 01.37976 -28 13 00.6888           ~ 3 0
47 NAME Sgr B1 MoC 17 47 02.0 -28 31 57           ~ 137 0
48 NAME Sgr B MoC 17 47 02 -28 25.4           ~ 201 0
49 2MASS J17470898-2829561 * 17 47 08.982 -28 29 56.13           ~ 12 0
50 NAME Sgr B2 (North) Rad 17 47 20.2 -28 22 21           ~ 566 1
51 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 2020 1
52 NAME Large Molecule Heimat MoC 17 47 20.4943 -28 22 11.656           ~ 114 0
53 NAME Sgr B2 Main Rad 17 47 20.5 -28 23 06           ~ 352 1
54 BGPS G000.656-00.045 mm 17 47 20.8414 -28 23 55.390           ~ 4 0
55 IRAS 17452-2823 cor 17 48 24.72672 -28 24 31.3380           ~ 11 0
56 NAME Sgr D MoC 17 48 41.75 -28 01 45.0           ~ 125 1
57 NAME Local Arm reg ~ ~           ~ 406 0
58 NAME Galactic Ridge ? ~ ~           ~ 450 1

    Equat.    Gal    SGal    Ecl

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2021.07.27-20:12:39

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