2002A&A...389..993G


Query : 2002A&A...389..993G

2002A&A...389..993G - Astronomy and Astrophysics, volume 389, 993-1014 (2002/7-3)

Interstellar CN toward CH+-forming regions.

GREDEL R., PINEAU DES FORETS G. and FEDERMAN S.R.

Abstract (from CDS):

Measurements on interstellar CN absorption are presented for stars in three southern OB associations, NGC 2439, Vela OB1, and CenOB1. CN is detected in 21 out of 31 stars observed. The doublet ratio for the R(1) and P(1) lines of the (0, 0) band of the B 2Σ+-X 2Σ+ violet system and a comparison of violet system data with measurements of the (1, 0) and (2, 0) bands of the A 2Π-X 2Σ+ red system are used to derive Doppler parameters and total column densities. Inferred CN column densities vary by more than an order of magnitude for lines of sight with similar CH column densities. Observations of the (0, 0) band of the CH B 2Σ-X 2Π system are used to revise previously published CH column densities toward the lines of sight studied in CN. Together with earlier results on CH, CH+, and C2, the CN data presented here provide a homogeneous set of column densities and radial velocities of diatomic molecules in three individual translucent clouds. We use these data to study CN production via chemical models. Gas densities are inferred from models based on production via CH and C2 in cool gas. Most sightlines in our sample test densities typical for diffuse molecular gas (a few hundred cm–3) when the ultraviolet flux permeating the gas is between 1 and 5 times the average interstellar flux. A few lines of sight indicate that CN is produced under dark cloud conditions because relatively large densities are obtained or because this simple chemical scheme is unable to reproduce the observed CN columns. Low densities are indicated for directions with upper limits on CN. We add an ad hoc component of a number of low-velocity (<10km/s) criss-crossing MHD shocks to explain observed column densities of interstellar CH+. These shocks also produce about 10 to 30% of the total CH column along the line of sight.

Abstract Copyright:

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

Simbad objects: 36

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Number of rows : 36
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 HD 52382 * 07 00 39.3386037216 -09 12 10.678042594 6.07 6.76 6.57 6.29 6.19 B0.5Ia 103 0
2 V* V569 Mon bC* 07 05 49.63971 -10 39 36.2907 5.55 6.44 6.49 7.55   B1II/III 104 0
3 HD 53975 SB* 07 06 35.9656022838 -12 23 38.216531612 5.38 6.40 6.50 6.51   O7.5Vz 183 0
4 NAME CMa OB1 As* 07 07.0 -10 28           ~ 129 0
5 HD 54662 SB* 07 09 20.2488124291 -10 20 47.627880802 5.35 6.24 6.21 7.23   O6.5Vz(n)+O7.5Vz 325 2
6 HD 55879 * 07 14 28.2530122374 -10 18 58.483790697 4.88 5.85 6.03 7.35   O9.7III 158 0
7 HD 61827 * 07 39 49.3379128922 -32 34 42.131834519 7.91 9.52 8.20 8.19   O8/9(Ib) 74 0
8 NGC 2439 OpC 07 40 45 -31 41.6   7.31 6.9     ~ 131 0
9 HD 62150 s*b 07 41 13.3242733866 -32 38 38.210267489 7.88 8.20 7.67 8.48   B3Iab 63 0
10 CD-32 4348 s*b 07 44 26.4304067171 -33 13 18.598740308 10.11 10.05 9.19 9.30   B3Ia 37 0
11 HD 62844 * 07 44 34.9042781883 -32 14 19.776611460 8.45 9.06 9.05 8.65   B2Ia 36 0
12 CD-33 4141 * 07 47 13.1506716324 -33 20 30.035514281 11.11 11.15 9.88 9.72   B2.5I: 19 0
13 HD 63423 Be* 07 47 35.3976466639 -30 32 55.041350559 7.55 8.87 8.67 8.63   B1Ib/II 39 0
14 HD 73882 EB* 08 39 09.53412 -40 25 09.2608 7.07 7.59 7.19 6.67 6.30 O8.5IV 225 2
15 HD 74371 s*b 08 41 56.9095084143 -45 24 38.559171310 4.94 5.378 5.227 6.75   B6Iab/b 86 0
16 HD 75149 s*b 08 46 30.5468343288 -45 54 45.012400213 5.25 5.677 5.459 6.77   B5Iab 101 0
17 HD 75211 * 08 47 01.5923441172 -44 04 28.844578224 7.35 7.90 7.50 8.28   O8.5II((f)) 82 0
18 Ass Vel OB 1 As* 08 49.9 -45 00           ~ 94 0
19 CD-44 4865 * 08 50 02.2861134697 -44 34 39.913243836 9.88 10.16 9.63 9.67   B0III 49 0
20 CD-45 4676 Be* 08 53 22.009 -46 02 08.78 9.54 9.93 9.17 9.39   O9.5II 37 0
21 HD 76556 * 08 55 07.1450998466 -47 36 27.155801455 8.03 8.61 8.20 8.90   O6IV(n)((f))p 71 1
22 CD-46 4786 * 08 56 55.8415999071 -47 02 45.523035446 9.71 9.95 9.49 9.47   B1Ib 37 0
23 HD 78344 * 09 05 51.3293958719 -47 46 06.830657900 10.10 10.12 9.00 8.55 8.16 O9.5/B0(Ib) 72 0
24 HD 110639 * 12 44 17.0842708574 -61 23 40.696922138 8.90 9.15 8.46 9.01   B1II-III 42 0
25 HD 111904 V* 12 53 21.8939526500 -60 19 42.561485784 5.75 6.05 5.77 7.09   B9Iab 102 0
26 NGC 4755 OpC 12 53 39 -60 21.7           ~ 270 0
27 V* CC Cru El* 12 53 47.2743079060 -60 19 55.346496967 7.44 8.00 7.83 7.68   B2III 29 0
28 * kap Cru SB* 12 53 48.9195114429 -60 22 34.468234629 5.62 6.12 5.94 7.12   B2/3Ia 122 0
29 HD 111990 * 12 53 59.7990827718 -60 20 07.505578149 6.46 6.95 6.77 7.68   B1/2Ib 78 1
30 Ass Cen OB 1 As* 13 02 -61.4           ~ 104 0
31 HD 113422 * 13 04 36.8519896213 -61 42 37.013684933 8.87 9.07 8.24 9.04   B1/2Ia/ab 62 0
32 HD 113432 Em* 13 04 49.3230284151 -63 29 29.247253988 9.4 9.70 9.19 9.40   B1Ib 39 0
33 HD 114011 * 13 08 43.0544949595 -61 11 10.965832008 9.8 10.08 9.36 9.59   B3/5Ib/II 47 0
34 HD 114213 * 13 10 21.3700451292 -61 28 20.892945879 9.86 9.88 8.96 9.40   B1Ib 72 0
35 HD 114886 ** 13 14 44.38260 -63 34 51.8077 6.15 6.98 6.89 7.76   O9-B0V 93 0
36 HD 115704 * 13 20 12.4026297479 -62 00 22.450542752 8.06 8.62 8.19 8.93   B0.5Iab 40 0

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2021.08.04-14:43:04

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