# 2010A&A...520A..49S

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 Query : 2010A&A...520A..49S

2010A&A...520A..49S - Astronomy and Astrophysics, volume 520, A49-49 (2010/9-2)

Dynamic star formation in the massive DR21 filament.

SCHNEIDER N., CSENGERI T., BONTEMPS S., MOTTE F., SIMON R., HENNEBELLE P., FEDERRATH C. and KLESSEN R.

Abstract (from CDS):

The formation of massive stars is a highly complex process in which it is unclear whether the star-forming gas is in global gravitational collapse or an equilibrium state supported by turbulence and/or magnetic fields. In addition, magnetic fields may play a decisive role in the star-formation process since they influence the efficiency of gas infall onto the protostar. By studying one of the most massive and dense star-forming regions in the Galaxy at a distance of less than 3 kpc, i.e. the filament containing the well-known sources DR21 and DR21(OH), we attempt to obtain observational evidence to help us to discriminate between these two views. We use molecular line data from our 13CO 1-0, CS 2-1, and N2H+ 1-0 survey of the Cygnus X region obtained with the FCRAO and high-angular resolution observations in isotopomeric lines of CO, CS, HCO+, N2H+, and H2CO, obtained with the IRAM 30 m telescope, to investigate the distribution of the different phases of molecular gas. Gravitational infall is identified by the presence of inverse P Cygni profiles that are detected in optically thick lines, while the optically thinner isotopomers are found to reach a peak in the self-absorption gap. We observe a complex velocity field and velocity dispersion in the DR21 filament in which regions of the highest column-density, i.e., dense cores, have a lower velocity dispersion than the surrounding gas and velocity gradients that are not (only) due to rotation. Infall signatures in optically thick line profiles of HCO+ and 12CO are observed along and across the whole DR21 filament. By modelling the observed spectra, we obtain a typical infall speed of ∼0.6km/s and mass accretion rates of the order of a few 10–3M/yr for the two main clumps constituting the filament. These massive clumps (4900 and 3300M at densities of around 105cm–3 within 1pc diameter) are both gravitationally contracting (with free-fall times much shorter than sound crossing times and low virial parameter α). The more massive of the clumps, DR21(OH), is connected to a sub-filament, apparently falling'' onto the clump. This filament runs parallel to the magnetic field. All observed kinematic features in the DR21 filament (velocity field, velocity dispersion, and infall), its filamentary morphology, and the existence of (a) sub-filament(s) can be explained if the DR21 filament was formed by the convergence of flows on large scales and is now in a state of global gravitational collapse. Whether this convergence of flows originated from self-gravity on larger scales or from other processes cannot be determined by the present study. The observed velocity field and velocity dispersion are consistent with results from (magneto)-hydrodynamic simulations where the cores lie at the stagnation points of convergent turbulent flows.

Journal keyword(s): ISM: clouds - ISM: individual objects: Cygnus X - ISM: molecules - ISM: kinematics and dynamics - radio lines: ISM - submillimeter: ISM

Nomenclature: Fig. 3, Text: [SCB2010] FN (Nos F1-F3).

Full paper

 Number of rows : 23
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 V* R Leo Mi* 09 47 33.4839808805 +11 25 43.823283729 9.22 8.94 7.53 3.39 0.12 M7-9e 897 1
2 SNR G030.8-00.0 SNR 18 47 32 -01 56.5           ~ 502 0
3 * chi Cyg S* 19 50 33.9213430345 +32 54 50.575531294 7.02 6.06 4.24 1.81 -0.01 S6-9/1-2e 686 0
4 NAME Northern Coalsack DNe 20 21 +37.0           ~ 111 0
5 SH 2-106 HII 20 27 26.8 +37 22 49           ~ 432 2
6 NAME Cyg X Cld 20 28 41 +41 10.2           ~ 765 1
7 RAFGL 2591 Y*O 20 29 24.8230 +40 11 19.590           ~ 607 0
8 Ass Cyg OB 2 As* 20 33.2 +41 19           ~ 894 0
9 18P 64 Rad 20 35 08.4 +41 13 20           ~ 23 0
10 DR 17 HII 20 35.2 +42 25           ~ 41 0
11 IRAS 20346+4031 IR 20 36 28.5 +40 41 44           ~ 9 0
12 18P 73 Rad 20 36 55.9 +41 36 29           ~ 45 0
13 NAME Cyg X FIR 33 Y*O 20 38 35.9 +42 37 22           B1.5 384 1
14 [DKS2007] B 3-1 IR 20 38 59.9 +42 20 51           ~ 2 0
15 NAME DR 21(OH) MM 2 Mas 20 39 00.4 +42 22 44           ~ 40 0
16 [MBS2007c] CygX-N44 Rad 20 39 01.01 +42 22 50.2           ~ 389 0
17 GRS G081.70 +00.50 SFR 20 39 01.6 +42 19 38           O4.5 1019 0
18 DR 22 HII 20 39 16.67 +41 18 44.7           ~ 47 1
19 2MASS J20391672+4216090 Y*O 20 39 16.72824 +42 16 09.0912           ~ 16 0
20 [DKS2007] A 3-1 IR 20 39 19.2 +42 14 53           ~ 2 0
21 DR 23 Rad 20 40.8 +41 54           ~ 39 0
22 V* T Cep Mi* 21 09 31.7834766408 +68 29 27.231070884 9.15 8.82 7.33     M6-9e 377 0
23 NAME Great Rift reg ~ ~           ~ 18 0

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2023.03.27-06:16:14