2006A&A...450..569P


Query : 2006A&A...450..569P

2006A&A...450..569P - Astronomy and Astrophysics, volume 450, 569-583 (2006/5-1)

Ammonia in infrared dark clouds.

PILLAI T., WYROWSKI F., CAREY S.J. and MENTEN K.M.

Abstract (from CDS):

While low mass clouds have been relatively well studied, our picture of high-mass star formation remains unclear. Infrared Dark Clouds appear to be the long sought population of cold and dense aggregations with the potential of harbouring the earliest stages of massive star formation. Up to now there has been no systematic study on the temperature distribution, velocity fields, chemical and physical state toward this new cloud population. Knowing these properties is crucial for understanding the presence, absence and the very potential of star formation. The present paper aims at addressing these questions. We analyse temperature structures and velocity fields and gain information on their chemical evolution. We mapped the (J,K)=(1,1) and (2,2) inversion transitions of ammonia in 9 infrared dark clouds. Our observations allow the most reliable determination of gas temperatures in IRDCs to date. The gas emission is remarkably coextensive with the extinction seen at infrared wavelengths and with the submillimeter dust emission. Our results show that IRDCs are on average cold (T<20K) and have variations among the different cores. IRDC cores are in virial equilibrium, are massive (M>100M), highly turbulent (1-3km/s) and exhibit significant velocity structure (variations around 1-2km/s over the cloud). We find an increasing trend in temperature from IRDCs with high ammonia column density to high mass protostellar objects and Ultracompact Hii regions, stages of early warm high-mass star formation. The linewidths of IRDCs are smaller than those observed in high mass protostellar objects and hot core/Ultracompact Hii regions. On basis of this sample, and by comparison of the ammonia gas properties within a cloud and between different clouds, we infer that while active star formation is not yet pervasive in most IRDCs, local condensations might collapse in the future or have already begun forming stars.

Abstract Copyright:

Journal keyword(s): stars: formation - ISM: molecules - radio lines: ISM - ISM: kinematics and dynamics

Nomenclature: Table 1: [PWC2006] NH3 GLL.ll+B.bb N=7. Table 3: [PWC2006] NH3 GLL.ll+B.bb PN N=18.

Simbad objects: 42

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Number of rows : 42
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 Perseus Cloud SFR 03 35.0 +31 13           ~ 1363 0
2 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4412 0
3 M 42 HII 05 35 17 -05 23.4           ~ 4071 0
4 NAME Ori A MoC 05 38 -07.1           ~ 3007 0
5 Ass Gem OB 1 As* 06 09.8 +21 35           ~ 191 0
6 IC 443 SNR 06 17 00.0000000 +22 34 11.998901           ~ 1234 1
7 NAME NGC 6334-I Cl* 17 20 53.35 -35 47 01.5           ~ 342 0
8 QSO B1741-038 QSO 17 43 58.85613537 -03 50 04.6167326     20.40 17.98   ~ 548 1
9 PSR B1806-19.3 Psr 18 09 43.147 -19 17 38.10           ~ 100 1
10 SNR G011.0+00.0 SNR 18 10.1 -19 25           ~ 35 1
11 GAL 010.61-00.38 HII 18 10 25.77 -19 56 04.5           ~ 5 0
12 MMB G011.109-00.114 Y*O 18 10 28.25 -19 22 29.1           ~ 56 0
13 [CCE98b] 011.11-0.12 Cld 18 10.5 -19 23           ~ 99 2
14 AGAL G019.286+00.082 Y*O 18 25 52.11528 -12 04 49.8900           ~ 28 0
15 [CCE98b] 019.30+0.07 Cld 18 25 56.78 -12 04 25.0           ~ 13 0
16 [PWC2006] NH3 G19.30+0.07 P1 cor 18 25 58.5 -12 03 59           ~ 7 0
17 [PWC2006] NH3 G24.63+0.15 Cld 18 35 40.44 -07 18 42.3           ~ 4 0
18 [PWC2006] NH3 G24.72-0.75 Cld 18 36 21.07 -07 41 37.7           ~ 1 0
19 AGAL G028.344+00.061 cor 18 42 50.45 -04 03 17.7           ~ 85 0
20 AGAL G028.398+00.081 cor 18 42 51.86 -03 59 43.3           ~ 52 0
21 IRAS 18402-0403 IR 18 42 54.9 -04 00 13           ~ 12 0
22 SNR G033.6+00.1 SNR 18 52 29.000 +00 38 42.00           ~ 285 1
23 [PWC2006] NH3 G33.71-0.01 Cld 18 52 53.81 +00 41 06.4           ~ 4 0
24 RAFGL 2271 SFR 18 53 18.54 +01 14 57.9           ~ 504 0
25 NAME W51 IR Dark Cloud cor 19 21 45.3 +13 49 22           ~ 21 0
26 [PWC2006] NH3 G79.27+0.38 Cld 20 31 59.61 +40 18 26.4           ~ 11 0
27 [PWC2006] NH3 G79.34+0.33 Cld 20 32 21.803 +40 20 08.00           ~ 13 0
28 [PWC2006] NH3 G81.50+0.14 Cld 20 40 08.29 +41 56 26.4           ~ 2 0
29 NGC 7027 PN 21 07 01.571952 +42 14 10.47120   10.358 8.831 10.157   ~ 2456 1
30 [PWC2006] NH3 G11.11-0.12 P3 smm ~ ~           ~ 4 0
31 [PWC2006] NH3 G28.34+0.06 P5 Cld ~ ~           ~ 1 0
32 [PWC2006] NH3 G33.71-0.01 P2 Cld ~ ~           ~ 1 0
33 [PWC2006] NH3 G79.27+0.38 P3 Cld ~ ~           ~ 1 0
34 [PWC2006] NH3 G11.11-0.12 P2 smm ~ ~           ~ 4 0
35 [PWC2006] NH3 G24.72-0.17 P1 Cld ~ ~           ~ 1 0
36 [PWC2006] NH3 G28.34+0.06 P4 Cld ~ ~           ~ 1 0
37 [PWC2006] NH3 G33.71-0.01 P1 Cld ~ ~           ~ 1 0
38 [PWC2006] NH3 G79.27+0.38 P2 Cld ~ ~           ~ 1 0
39 [PWC2006] NH3 G79.27+0.38 P1 Cld ~ ~           ~ 1 0
40 [PWC2006] NH3 G79.34+0.33 P1 Cld ~ ~           ~ 1 0
41 [PWC2006] NH3 G11.11-0.12 P4 smm ~ ~           ~ 3 0
42 [PWC2006] NH3 G28.34+0.06 P3 Cld ~ ~           ~ 2 0

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