2010A&A...518A..45L

Query : 2010A&A...518A..45L

2010A&A...518A..45L - Astronomy and Astrophysics, volume 518A45-45 (2010/7-2)

The CO luminosity and CO-H2 conversion factor of diffuse ISM: does CO emission trace dense molecular gas?

LISZT H.S., PETY J. and LUCAS R.

Abstract (from CDS):

We wish to separate and quantify the CO luminosity and CO-H2 conversion factor applicable to diffuse but partially-molecular ISM when H2 and CO are present but C+ is the dominant form of gas-phase carbon. We discuss galactic lines of sight observed in HI, HCO+ and CO where CO emission is present but the intervening clouds are diffuse (locally A_V≲1mag) with relatively small CO column densities NCO≲2x1016cm–2. We separate the atomic and molecular fractions statistically using EB–V as a gauge of the total gas column density and compare NH2 to the observed CO brightness. Although there are H2-bearing regions where CO emission is too faint to be detected, the mean ratio of integrated CO brightness to NH2 for diffuse ISM does not differ from the usual value of 1Kkm/s of integrated CO brightness per 2x1020 H2cm–2. Moreover, the luminosity of diffuse CO viewed perpendicular to the galactic plane is 2/3 that seen at the Solar galactic radius in surveys of CO emission near the galactic plane. Commonality of the CO-H2 conversion factors in diffuse and dark clouds can be understood from considerations of radiative transfer and CO chemistry. There is unavoidable confusion between CO emission from diffuse and dark gas and misattribution of CO emission from diffuse to dark or giant molecular clouds. The character of the ISM is different from what has been believed if CO and H2 that have been attributed to molecular clouds on the verge of star formation are actually in more tenuous, gravitationally-unbound diffuse gas.

Abstract Copyright: ∼

Journal keyword(s): ISM: molecules - ISM: clouds

Simbad objects: 103

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Number of rows : 103
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 4C 55.42 Rad 00 00 20.447 +55 39 08.51           ~ 8 1
2 NVSS J000833+683721 rG 00 08 33.47278559 +68 37 22.0488632           ~ 17 1
3 4C 60.01 Rad 00 14 48.79214510 +61 17 43.5424331           ~ 41 1
4 QSO B0016+73 Bla 00 19 45.78637230 +73 27 30.0176020     19.00 18.26   ~ 313 1
5 4C 66.02 Rad 00 44 41.3 +66 18 41           ~ 11 1
6 8C 0052+681 Sy2 00 56 01.122 +68 22 29.53           ~ 74 1
7 4C 66.03 Rad 01 00 03.9274093560 +66 50 57.201768060           ~ 8 1
8 7C 0059+5808 Bla 01 02 45.76237340 +58 24 11.1366164   20.09 19.22 18.57 17.90 ~ 262 1
9 4C 56.02 BLL 01 10 57.55296762 +56 32 16.9490748           ~ 25 1
10 ICRF J012830.5+630629 AG? 01 28 30.56507620 +63 06 29.8820490           ~ 23 1
11 4C 61.04 Rad 02 09 38.3 +61 41 15           ~ 16 1
12 6C 021252+733537 BLL 02 17 30.81335327 +73 49 32.6217355     19.00 18.97   ~ 485 1
13 4C 67.05 Bla 02 28 50.05148365 +67 21 03.0293322   19.5 19.50 18.1   ~ 264 1
14 QSO B0235+1624 BLL 02 38 38.93010450 +16 36 59.2745528   16.46 15.50 15.92   ~ 1614 2
15 ICRF J024457.6+622806 Sy1 02 44 57.6967097952 +62 28 06.517098084   12.15 12.19     ~ 310 2
16 4C 47.08 BLL 03 03 35.24221958 +47 16 16.2754726   17.54 16.95 16.2   ~ 292 1
17 NGC 1275 Bla 03 19 48.1599902040 +41 30 42.108850836   13.10 12.48 11.09   ~ 4243 3
18 4C 53.07 Rad 03 36 27.9 +53 38 52           ~ 18 1
19 1RXS J033739.9+504551 QSO 03 37 43.0496630448 +50 45 47.850441912           ~ 53 1
20 6C 035545+504923 Bla 03 59 29.74727351 +50 57 50.1618607           ~ 480 1
21 3C 103 rG 04 08 03.343 +43 00 24.42   19       ~ 78 1
22 4C 38.13 Rad 04 09 22.422 +38 48 32.91           ~ 14 1
23 3C 111 Sy1 04 18 21.2772425736 +38 01 35.801359968   19.75 18.05     ~ 1002 2
24 NVSS J042355+415003 BLL 04 23 56.00979158 +41 50 02.7129362   19   19.2   ~ 123 1
25 2C 396 QSO 04 32 36.50262174 +41 38 28.4497778     20.0     ~ 231 1
26 4C 58.11 Rad 04 34 56.762 +58 46 38.60           ~ 4 1
27 4C 48.13 BLL 04 38 59.1 +48 48 47           ~ 25 1
28 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4971 0
29 NVSS J044646+503737 Rad 04 46 46.41918 +50 37 39.1315           ~ 23 1
30 4C 47.15 BLL 05 02 25.88525 +47 46 04.5393           ~ 15 1
31 6C 050923+403809 BLL 05 12 52.54284173 +40 41 43.6203455           ~ 68 1
32 QSO J0530+13 Bla 05 30 56.41674741 +13 31 55.1494688     20.00 19.35   ~ 1004 1
33 NAME Ori A MoC 05 38 -07.1           ~ 3187 0
34 7C 055201.39+394824.00 Bla 05 55 30.80561419 +39 48 49.1649683     18.30 17.5   ~ 527 2
35 3C 152 Rad 06 04 28.628 +20 21 21.72           ~ 59 1
36 QSO B0605-0834 BLL 06 07 59.69924014 -08 34 49.9783246     17.60 17.70   ~ 487 1
37 QSO B0607-157 Bla 06 09 40.94954062 -15 42 40.6727537   18.47 18.00 19.90   ~ 330 1
38 4C 14.18 BLL 06 25 45.9222413976 +14 40 19.738875648           ~ 47 2
39 2C 553 QSO 06 27 10.125 -05 53 06.21           ~ 165 1
40 4C 10.20 Rad 06 32 15.302 +10 22 02.17           ~ 37 1
41 NVSS J063243+155957 Rad 06 32 43.13551833 +15 59 57.6200445           ~ 21 1
42 4C 08.21 Rad 06 33 12.995 +08 13 19.97           ~ 20 1
43 PKS 0704-23 rG 07 06 33.5180238240 -23 11 37.853088900           ~ 37 1
44 PKS 0709-20 Rad 07 11 47.270 -20 43 14.07           ~ 21 1
45 QSO J0730-116 Bla 07 30 19.11247452 -11 41 12.6006642     20.30 20.3   ~ 323 1
46 PKS 0733-17 Rad 07 35 45.81247503 -17 35 48.5024157           ~ 65 1
47 QSO B0736+01 Bla 07 39 18.03389906 +01 37 04.6177501   16.90 16.47 16.19   ~ 738 1
48 4C 39.25 Bla 09 27 03.01394144 +39 02 20.8518067   17.17 17.00 16.486   ~ 1036 1
49 6C 095456+654857 BLL 09 58 47.2451872176 +65 33 54.819354600     17.0 15.75   ~ 771 1
50 4C 01.28 BLL 10 58 29.60520810 +01 33 58.8237454   18.74 18.28 16.68   ~ 828 2
51 NAME Polaris Flare MoC 11 00 14.8 +86 10 52           ~ 215 1
52 3C 273 BLL 12 29 06.6998257176 +02 03 08.597629980   13.05 14.830 14.11   ~ 6022 1
53 3C 279 Bla 12 56 11.16657958 -05 47 21.5251510   18.01 17.75 15.87   ~ 3205 2
54 QSO B1334-127 Bla 13 37 39.78278132 -12 57 24.6933925   18.5 19.00 16.22   ~ 540 1
55 NAME zet Oph Cloud Cld 16 37 09 -10 34.0           ~ 114 0
56 3C 345 Bla 16 42 58.80997043 +39 48 36.9939552   16.81 16.59 16.84   ~ 1808 3
57 LDN 204 DNe 16 47 47.3 -12 05 16           ~ 55 0
58 NVSS J170918-352521 Rad 17 09 18.66637647 -35 25 22.2024527           ~ 17 1
59 PMN J1714-2836 Rad 17 14 27.702 -28 36 27.46           ~ 4 1
60 ICRF J171736.0-334208 BLL 17 17 36.02929270 -33 42 08.8296186   20.93   17.3   ~ 136 1
61 ICRF J171738.6-394852 Rad 17 17 38.59990175 -39 48 52.6653049           ~ 16 0
62 QSO B1730-130 Bla 17 33 02.70578907 -13 04 49.5482119   18 19.50 18.78 17.39 ~ 1198 1
63 QSO B1741-038 Bla 17 43 58.85613537 -03 50 04.6167326     20.40 17.98   ~ 583 1
64 4C 09.57 BLL 17 51 32.81857326 +09 39 00.7284066   17.46 16.78 15.57   ~ 1007 1
65 PMN J1751-2524 Rad 17 51 51.26253123 -25 24 00.0635706           ~ 91 1
66 PMN J1820-0947 Rad 18 20 38.161 -09 47 17.15           ~ 9 1
67 PMN J1822-1309 Rad 18 22 10.8 -13 09 45           ~ 11 1
68 PMN J1822-0939 Rad 18 22 28.792 -09 38 57.03           ~ 49 1
69 4C 56.27 BLL 18 24 07.06837171 +56 51 01.4908155   18.9 19.30 16.48   ~ 510 1
70 PMN J1832-1035 rG 18 32 20.83647 -10 35 11.1968           ~ 107 1
71 2C 1590 BLL 18 45 37.622 +09 53 44.74           ~ 82 1
72 QSO J1851+005 QSO 18 51 46.72295 +00 35 32.3649           ~ 138 1
73 3C 395 Bla 19 02 55.93889653 +31 59 41.7016439     17.5     ~ 281 2
74 PMN J1908-1855 Rad 19 08 15.257 -18 55 52.86           ~ 4 1
75 SS 433 HXB 19 11 49.5647697480 +04 58 57.827127648   16.854 14.643     A7Ib 2253 4
76 [VV2006] J191154.1-210244 Bla 19 11 53.9382469416 -21 02 43.797069420     17.00 17.9   ~ 32 1
77 ICRF J191158.2+161146 Bz? 19 11 58.25740170 +16 11 46.8652526           ~ 48 1
78 NVSS J191254+051801 Rad 19 12 54.25766259 +05 18 00.4214827           ~ 16 1
79 EQ 1915+062 Rad 19 17 48.8 +06 21 16           ~ 5 0
80 ICRF J192559.6+210626 BLL 19 25 59.60535459 +21 06 26.1620257           ~ 212 1
81 4C 73.18 BLL 19 27 48.4947009120 +73 58 01.572558816     16.06 15.11   ~ 562 2
82 ICRF J195248.2+252653 BLL 19 52 48.29397693 +25 26 53.4842452           ~ 13 0
83 QSO B1954+513 Bla 19 55 42.73825546 +51 31 48.5461173     18.5 17.34   ~ 247 1
84 QSO B2005+40 Bla 20 07 44.9449261536 +40 29 48.603352020   18.5 19.00 20.3   ~ 319 1
85 4C 24.48 Rad 20 09 25.197 +25 05 47.03           ~ 12 1
86 QSO J2015+371 BLL 20 15 28.72978661 +37 10 59.5147372     21.82 21.4   ~ 324 2
87 4C 31.56 QSO 20 23 19.01734326 +31 53 02.3060318           ~ 125 1
88 ICRF J202355.8+542735 QSO 20 23 55.84397746 +54 27 35.8291002           ~ 40 1
89 QSO B2023+336 BLL 20 25 10.84210426 +33 43 00.2143556           ~ 188 1
90 4C 54.42 QSO 20 31 47.9586852408 +54 55 03.138662316   18.7       ~ 48 1
91 3C 418.0 Bla 20 38 37.03472279 +51 19 12.6624988   21.30 21.00 18.9   ~ 333 1
92 5C 8.146 Bla 20 50 51.13146726 +31 27 27.3741323     19.7 15.9   ~ 92 1
93 4C 50.53 Rad 20 57 20.117 +50 58 15.86           ~ 8 1
94 HVABG 27 Rad 21 08 56.47 +49 41 56.1           ~ 2 0
95 4C 62.33 Rad 21 12 48.799 +62 15 00.82           ~ 25 1
96 4C 06.69 Bla 21 48 05.45866779 +06 57 38.6041877   16.85 16.47 15.06   ~ 703 1
97 4C 60.32 Rad 21 48 16.04229551 +61 07 05.7939686           ~ 31 1
98 3C 439 Rad 21 56 37.839 +48 30 28.36           ~ 10 1
99 NAME BL Lac BLL 22 02 43.2913536816 +42 16 39.979416792   15.66 14.72     ~ 2397 1
100 3C 454.3 Bla 22 53 57.7480438728 +16 08 53.561508864   16.57 16.10 15.22   ~ 3004 2
101 NVSS J225705+702839 BLL 22 57 05.6606406997 +70 28 40.074050061           ~ 9 1
102 4C 53.53 Rad 23 43 48.435 +53 48 39.95           ~ 10 1
103 3C 468.1 rG 23 50 54.845 +64 40 19.59           ~ 73 1

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