2000A&A...358.1069L


Query : 2000A&A...358.1069L

2000A&A...358.1069L - Astronomy and Astrophysics, volume 358, 1069-1076 (2000/6-3)

Comparative chemistry of diffuse clouds. I. C2H and C3H2.

LUCAS R. and LISZT H.S.

Abstract (from CDS):

Using the Plateau de Bure interferometer, we searched for λ3mm absorption lines of C2H, 3h2, C3H, and C4H from the diffuse and very marginally translucent clouds which lie toward a sample of compact extragalactic mm-wave continuum sources. The C2H survey in particular is nearly the equivalent of our earlier, exhaustive study of HCO+ absorption, albeit with lower signal/noise. C2H lines are found corresponding to all components detected in HCO+ which places C2H in a small group of the most ubiquitous molecules we have studied - OH, HCO+ and, from this work, C2H and 3h2. But the relationship between N(C2H) and N(HCO+) is highly non-linear, as seems to be the case for all species beside OH. N(C2H)/N(HCO+) is actually relatively high at small N(HCO+), 20-40, and declines at higher column density despite a typically steep increase of N(C2H) around N(HCO+)≃1012cm–2. On the whole we find a mean over all features of <N(C2H)/N(HCO+)≥14.5±6.7 or <N(C2H)/N(H2)≥∼2.9±1.3x10–8. By contrast, C2H and ortho cyclic-3h2 vary in nearly fixed proportion, <N(C2H)/N(3h2-(o))≥27.7±8.0, leading to a total 3h2 abundance N(3h2)/N(H2)≃1.4±0.7x10–9 and (<N(3h2)/N(HCO+)≥∼0.7. Our observations of the high-lying C4H lines at 95GHz do not place sensitive limits on N(C4H)/N(HCO+). The C3H data are somewhat more restrictive, and we find N(C3H)/N(HCO+)<0.065 in one direction but more generally we have only that N(C3H)/N(HCO+)<4. The linewidths of C2H, 3h2, and HCO+ are sensibly identical. In comparing the abundances of many simple species in diffuse, translucent, and dark gas, we see that the relative abundances of OH, HCO+, CH, and C2H are relatively constant, but those of 3h2 and C3H are noticeably larger in TMC-1.

Abstract Copyright:

Journal keyword(s): ISM: abundances - ISM: clouds - ISM: molecules - ISM: structure - radio lines: ISM

Simbad objects: 29

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Number of rows : 29
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 6C 021252+733537 BLL 02 17 30.8129232696 +73 49 32.622815712     19.0 18.97   ~ 425 1
2 4C 67.05 QSO 02 28 50.0509728096 +67 21 03.034681488   19.5   18.1   ~ 240 1
3 3C 84 Sy2 03 19 48.1599902040 +41 30 42.108850836   13.10 12.48 11.09   ~ 3778 3
4 4C 50.11 QSO 03 59 29.7469819512 +50 57 50.159106936           ~ 416 1
5 3C 111 Sy1 04 18 21.2772425736 +38 01 35.801359968   19.75 18.05     ~ 897 1
6 QSO B0420-0127 QSO 04 23 15.8007747432 -01 20 33.063518580   17.50 17.00 16.28   ~ 1129 3
7 TMC-1 MoC 04 41 45.9 +25 41 27           ~ 1525 0
8 QSO J0530+13 Bla 05 30 56.4168902136 +13 31 55.151893344     20.0 19.35   ~ 914 1
9 7C 055201.39+394824.00 QSO 05 55 30.8055972888 +39 48 49.166341920     18.0 17.5   ~ 487 2
10 QSO B0607-157 QSO 06 09 40.9493089944 -15 42 40.667570496   18.47 18.0 19.90   ~ 299 1
11 QSO B0736+01 QSO 07 39 18.0339358560 +01 37 04.618841340   16.90 16.47 16.19   ~ 648 1
12 ICRF J092703.0+390220 Sy1 09 27 03.0138528936 +39 02 20.850343332   17.17 17.00 16.486   ~ 959 1
13 6C 095456+654857 BLL 09 58 47.2451872176 +65 33 54.819354600     17.0 15.75   ~ 653 1
14 4C 01.28 BLL 10 58 29.6054370384 +01 33 58.820502924   18.74 18.28 16.68   ~ 711 2
15 3C 273 BLL 12 29 06.6998257176 +02 03 08.597629980   13.05 14.830 14.11   ~ 5569 1
16 3C 279 Bla 12 56 11.1663795384 -05 47 21.528432492   18.01 17.75 15.87   ~ 2870 2
17 QSO B1334-127 QSO 13 37 39.7829208840 -12 57 24.693846264   18.5 18.5 16.22   ~ 457 1
18 3C 345 QSO 16 42 58.8102993888 +39 48 37.002763188   16.81 16.59 16.84   ~ 1624 2
19 QSO B1730-130 QSO 17 33 02.7055087032 -13 04 49.545516612   18 18.5 18.78 17.39 ~ 1059 1
20 QSO B1741-038 QSO 17 43 58.8561752304 -03 50 04.618401684     18.5 17.98   ~ 508 1
21 4C 09.57 BLL 17 51 32.8186120872 +09 39 00.728629416   17.46 16.78 15.57   ~ 880 1
22 4C 56.27 BLL 18 24 07.0679485560 +56 51 01.479645612   18.9 18.4 16.48   ~ 453 1
23 QSO B1908-202 QSO 19 11 09.6526857480 -20 06 55.109271780   18.21   18.14   ~ 252 0
24 4C 73.18 BLL 19 27 48.4947009120 +73 58 01.572558816     15.5 15.11   ~ 507 2
25 QSO B1954+513 QSO 19 55 42.7384954488 +51 31 48.542394936     18.5 17.34   ~ 227 1
26 3C 418.0 QSO 20 38 37.0347144096 +51 19 12.660083976   21.30 20.00 18.9   ~ 286 0
27 4C 06.69 QSO 21 48 05.4586454304 +06 57 38.602799388   16.85 16.47 15.06   ~ 628 1
28 NAME BL Lac BLL 22 02 43.2913536816 +42 16 39.979416792   15.66 14.72     ~ 2130 1
29 3C 454.3 Bla 22 53 57.7480438728 +16 08 53.561508864   16.57 16.10 15.22   ~ 2673 2

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2022.06.27-04:44:22

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