2009ApJ...699.1092H

Query : 2009ApJ...699.1092H

2009ApJ...699.1092H - Astrophys. J., 699, 1092-1103 (2009/July-2)

Re-examining Larson's scaling relationships in Galactic molecular clouds.

HEYER M., KRAWCZYK C., DUVAL J. and JACKSON J.M.

Abstract (from CDS):

The properties of Galactic molecular clouds tabulated by Solomon et al. (SRBY) are re-examined using the Boston University-FCRAO Galactic Ring Survey of 13CO J = 1-0 emission. These new data provide a lower opacity tracer of molecular clouds and improved angular and spectral resolution compared with previous surveys of molecular line emission along the Galactic Plane. We calculate giant molecular cloud (GMC) masses within the SRBY cloud boundaries assuming local thermodynamic equilibrium (LTE) conditions throughout the cloud and a constant H2 to 13CO abundance, while accounting for the variation of the 12C/13C with galactocentric radius. The LTE-derived masses are typically five times smaller than the SRBY virial masses. The corresponding median mass surface density of molecular hydrogen for this sample is 42 M ☉/pc2, which is significantly lower than the value derived by SRBY (median 206 M☉/pc2) that has been widely adopted by most models of cloud evolution and star formation. This discrepancy arises from both the extrapolation by SRBY of velocity dispersion, size, and CO luminosity to the 1 K antenna temperature isophote that likely overestimates the GMC masses and our assumption of constant 13CO abundance over the projected area of each cloud. Owing to the uncertainty of molecular abundances in the envelopes of clouds, the mass surface density of GMCs could be larger than the values derived from our 13CO measurements. From velocity dispersions derived from the 13CO data, we find that the coefficient of the cloud structure functions, v°= σv/R 1/2, is not constant, as required to satisfy Larson's scaling relationships, but rather systematically varies with the surface density of the cloud as ~Σ0.5 as expected for clouds in self-gravitational equilibrium.

Abstract Copyright: ∼

Journal keyword(s): ISM: clouds - ISM: kinematics and dynamics

VizieR on-line data: <Available at CDS (J/ApJ/699/1092): table1.dat>

Simbad objects: 163

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Number of rows : 163
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4416 0
2 NGC 2024 Cl* 05 41 43 -01 50.5           ~ 1154 1
3 NGC 2264 OpC 06 40 52.1 +09 52 37           ~ 1793 0
4 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3631 1
5 SRBY 64 MoC 18 25.4 -12 30           ~ 2 0
6 SRBY 68 MoC 18 26.1 -12 05           ~ 2 0
7 SRBY 72 MoC 18 26.5 -11 44           ~ 2 0
8 SRBY 67 MoC 18 26.9 -12 17           ~ 2 0
9 SRBY 70 MoC 18 27.1 -11 52           ~ 2 0
10 SRBY 74 MoC 18 28.6 -11 50           ~ 2 0
11 SRBY 80 MoC 18 28.6 -10 47           ~ 4 0
12 SRBY 71 MoC 18 29.2 -12 07           ~ 2 0
13 SRBY 81 MoC 18 29.2 -10 44           ~ 2 0
14 SRBY 79 MoC 18 29.3 -10 51           ~ 4 0
15 SRBY 73 MoC 18 29.4 -11 59           ~ 2 0
16 SRBY 87 MoC 18 29.5 -10 01           ~ 2 0
17 SRBY 75 MoC 18 29.6 -11 52           ~ 3 0
18 SRBY 78 MoC 18 30.0 -11 02           ~ 2 0
19 SRBY 77 MoC 18 30.1 -11 10           ~ 2 0
20 SRBY 86 MoC 18 30.1 -10 17           ~ 2 0
21 SRBY 82 MoC 18 30.4 -10 50           ~ 2 0
22 SRBY 89 MoC 18 30.7 -09 35           ~ 4 0
23 SRBY 85 MoC 18 30.8 -09 56           ~ 4 0
24 SRBY 91 MoC 18 30.9 -09 12           ~ 2 0
25 SRBY 99 MoC 18 31.0 -08 28           ~ 2 0
26 SRBY 95 MoC 18 31.4 -08 49           ~ 2 0
27 SRBY 96 MoC 18 31.5 -08 46           ~ 2 0
28 SRBY 90 MoC 18 31.7 -09 23           ~ 2 0
29 SRBY 88 MoC 18 32.4 -10 00           ~ 2 0
30 SRBY 92 MoC 18 32.5 -09 15           ~ 2 0
31 SRBY 103 MoC 18 32.6 -07 59           ~ 2 0
32 SRBY 84 MoC 18 32.7 -10 25           ~ 2 0
33 SRBY 93 MoC 18 33.1 -09 19           ~ 2 0
34 SRBY 98 MoC 18 33.2 -08 52           ~ 2 0
35 SRBY 102 MoC 18 33.5 -08 15           ~ 2 0
36 SRBY 94 MoC 18 33.6 -09 10           ~ 2 0
37 SRBY 97 MoC 18 34.5 -09 00           ~ 3 0
38 SRBY 105 MoC 18 34.5 -07 55           ~ 3 0
39 SRBY 100 MoC 18 34.7 -08 35           ~ 3 0
40 SRBY 109 MoC 18 35.2 -07 25           ~ 2 0
41 SRBY 101 MoC 18 35.6 -08 34           ~ 2 0
42 SRBY 106 MoC 18 35.6 -07 46           ~ 4 0
43 SRBY 119 MoC 18 36.2 -06 40           ~ 2 0
44 SRBY 124 MoC 18 36.4 -06 06           ~ 2 0
45 SRBY 111 MoC 18 36.5 -07 34           ~ 2 0
46 SRBY 117 MoC 18 36.5 -07 22           ~ 3 0
47 SRBY 110 MoC 18 36.6 -07 42           ~ 2 0
48 SRBY 131 MoC 18 36.6 -05 30           ~ 2 0
49 SRBY 116 MoC 18 36.7 -07 29           ~ 5 0
50 SRBY 118 MoC 18 36.7 -06 49           ~ 4 0
51 SRBY 114 MoC 18 36.8 -07 36           ~ 2 0
52 SRBY 112 MoC 18 37.3 -07 45           ~ 2 0
53 SRBY 125 MoC 18 37.4 -06 18           ~ 3 0
54 SRBY 115 MoC 18 37.8 -07 42           ~ 2 0
55 SRBY 126 MoC 18 37.8 -06 09           ~ 2 0
56 SRBY 136 MoC 18 38.1 -05 19           ~ 2 0
57 SRBY 113 MoC 18 38.5 -07 50           ~ 2 0
58 SRBY 121 MoC 18 38.5 -06 49           ~ 3 0
59 SRBY 122 MoC 18 38.5 -06 31           ~ 4 0
60 SRBY 123 MoC 18 38.6 -06 40           ~ 2 0
61 SRBY 130 MoC 18 38.6 -05 57           ~ 2 0
62 SRBY 107 MoC 18 38.7 -07 55           ~ 2 0
63 SRBY 127 MoC 18 38.7 -06 30           ~ 2 0
64 SRBY 128 MoC 18 39.1 -06 19           ~ 5 0
65 SRBY 120 MoC 18 39.3 -06 45           ~ 3 0
66 SRBY 134 MoC 18 39.8 -05 38           ~ 2 0
67 SRBY 135 MoC 18 39.9 -05 35           ~ 2 0
68 SRBY 137 MoC 18 40.0 -05 33           ~ 2 0
69 SRBY 138 MoC 18 40.0 -05 17           ~ 2 0
70 SRBY 142 MoC 18 40.5 -05 00           ~ 2 0
71 SRBY 129 MoC 18 40.7 -06 28           ~ 2 0
72 SRBY 140 MoC 18 40.8 -05 25           ~ 2 0
73 SRBY 145 MoC 18 40.8 -04 43           ~ 2 0
74 SRBY 133 MoC 18 40.9 -05 49           ~ 2 0
75 SRBY 146 MoC 18 41.0 -04 46           ~ 2 0
76 SRBY 141 MoC 18 41.2 -05 19           ~ 3 0
77 SRBY 147 MoC 18 41.4 -04 40           ~ 2 0
78 SRBY 148 MoC 18 41.6 -04 35           ~ 2 0
79 SRBY 144 MoC 18 41.8 -05 02           ~ 2 0
80 SRBY 139 MoC 18 42.0 -05 27           ~ 2 0
81 SRBY 143 MoC 18 42.2 -05 07           ~ 2 0
82 SRBY 149 MoC 18 42.9 -04 14           ~ 2 0
83 SRBY 153 MoC 18 43.2 -03 36           ~ 2 0
84 SRBY 151 MoC 18 43.3 -04 10           ~ 4 0
85 SRBY 152 MoC 18 43.3 -03 50           ~ 5 0
86 SRBY 158 MoC 18 44.1 -03 29           ~ 4 0
87 SRBY 150 MoC 18 44.2 -04 21           ~ 2 0
88 SRBY 160 MoC 18 44.6 -02 59           ~ 2 0
89 SRBY 154 MoC 18 44.8 -03 48           ~ 3 0
90 SRBY 155 MoC 18 45.2 -03 38           ~ 2 0
91 SRBY 165 MoC 18 45.2 -02 02           ~ 3 0
92 SRBY 163 MoC 18 45.5 -02 39           ~ 2 0
93 SRBY 167 MoC 18 46.0 -01 58           ~ 2 0
94 SRBY 162 Mas 18 46 03.6 -02 39 26           ~ 31 1
95 SRBY 175 MoC 18 46.4 -01 34           ~ 2 0
96 SRBY 157 MoC 18 46.5 -03 24           ~ 2 0
97 SRBY 156 MoC 18 46.6 -03 49           ~ 2 0
98 SRBY 159 MoC 18 46.9 -03 28           ~ 2 0
99 SRBY 168 MoC 18 47.2 -02 07           ~ 3 0
100 SRBY 161 MoC 18 47.5 -03 14           ~ 2 0
101 SRBY 174 MoC 18 47.5 -01 43           ~ 2 0
102 SNR G030.8-00.0 SNR 18 47 32 -01 56.5           ~ 531 0
103 SRBY 170 MoC 18 47.6 -02 08           ~ 2 0
104 SRBY 172 MoC 18 48.2 -01 57           ~ 2 0
105 SRBY 177 MoC 18 48.4 -01 28           ~ 2 0
106 SRBY 180 MoC 18 48.4 -01 17           ~ 2 0
107 SRBY 178 MoC 18 48.6 -01 27           ~ 2 0
108 SRBY 164 MoC 18 48.7 -03 02           ~ 2 0
109 SRBY 169 MoC 18 48.8 -02 16           ~ 2 0
110 SRBY 179 MoC 18 49.6 -01 29           ~ 2 0
111 SRBY 182 MoC 18 49.6 -00 47           ~ 3 0
112 SRBY 173 MoC 18 49.8 -02 05           ~ 2 0
113 SRBY 183 MoC 18 49.8 -00 19           ~ 2 0
114 SRBY 181 MoC 18 50.7 -00 58           ~ 3 0
115 SRBY 184 MoC 18 51.7 -00 17           ~ 2 0
116 SRBY 189 MoC 18 52.0 +00 45           ~ 2 0
117 SRBY 186 MoC 18 52.2 +00 23           ~ 2 0
118 SRBY 187 MoC 18 52.6 +00 25           ~ 2 0
119 SRBY 191 MoC 18 52.8 +00 54           ~ 4 0
120 SRBY 190 MoC 18 53.1 +00 49           ~ 2 0
121 SRBY 193 MoC 18 53.5 +01 13           ~ 4 0
122 SRBY 188 MoC 18 53.6 +00 41           ~ 2 0
123 SRBY 192 MoC 18 54.0 +01 03           ~ 2 0
124 SRBY 198 MoC 18 54.0 +01 59           ~ 2 0
125 SRBY 185 MoC 18 54.1 +00 09           ~ 3 0
126 SRBY 195 MoC 18 54.7 +01 11           ~ 2 0
127 SRBY 205 MoC 18 54.9 +03 09           ~ 2 0
128 SRBY 196 MoC 18 55.2 +01 34           ~ 2 0
129 SRBY 202 MoC 18 55.9 +02 30           ~ 2 0
130 SRBY 203 MoC 18 57.2 +02 28           ~ 2 0
131 SRBY 206 MoC 18 58.1 +03 02           ~ 4 0
132 SRBY 207 MoC 18 58.3 +03 07           ~ 2 0
133 SRBY 204 MoC 18 58.7 +02 29           ~ 2 0
134 SRBY 208 MoC 18 58.9 +03 30           ~ 2 0
135 SRBY 209 MoC 18 59.0 +04 02           ~ 2 0
136 SRBY 210 MoC 18 59.5 +04 06           ~ 2 0
137 SRBY 211 MoC 19 01.0 +04 12           ~ 3 0
138 SRBY 212 MoC 19 01.7 +04 39           ~ 2 0
139 SRBY 213 MoC 19 04.0 +05 08           ~ 3 0
140 SRBY 214 MoC 19 04.8 +06 04           ~ 4 0
141 SRBY 215 MoC 19 06.5 +06 23           ~ 2 0
142 SRBY 216 MoC 19 06.9 +07 09           ~ 2 0
143 SRBY 217 MoC 19 07.2 +07 13           ~ 4 0
144 SRBY 219 MoC 19 09.0 +08 20           ~ 2 0
145 SRBY 218 MoC 19 09.3 +07 47           ~ 2 0
146 SRBY 220 MoC 19 10.5 +07 55           ~ 2 0
147 SRBY 221 MoC 19 10.7 +08 32           ~ 2 0
148 SRBY 223 MoC 19 12.1 +08 52           ~ 2 0
149 SRBY 224 MoC 19 13.3 +10 04           ~ 2 0
150 SRBY 225 MoC 19 14.3 +11 09           ~ 3 0
151 SRBY 227 MoC 19 16.7 +12 40           ~ 2 0
152 SRBY 226 MoC 19 16.9 +11 48           ~ 2 0
153 SRBY 229 MoC 19 20.5 +12 44           ~ 2 0
154 SRBY 232 MoC 19 20.5 +14 11           ~ 2 0
155 SRBY 236 MoC 19 24.0 +16 00           ~ 2 0
156 SRBY 234 MoC 19 24.7 +14 40           ~ 3 0
157 SRBY 237 MoC 19 26.1 +16 18           ~ 2 0
158 SRBY 238 MoC 19 28.1 +17 08           ~ 2 0
159 SRBY 243 MoC 19 29.6 +19 38           ~ 2 0
160 SRBY 241 MoC 19 29.9 +18 12           ~ 3 0
161 SRBY 240 MoC 19 30.5 +17 49           ~ 2 0
162 SRBY 242 MoC 19 31.8 +18 44           ~ 2 0
163 NAME Local Group GrG ~ ~           ~ 8389 0

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