2009MNRAS.395.1805D


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.29CET01:09:14

2009MNRAS.395.1805D - Mon. Not. R. Astron. Soc., 395, 1805-1821 (2009/June-1)

A large-scale CO survey of the Rosette molecular cloud: assessing the effects of O stars on surrounding molecular gas.

DENT W.R.F., HOVEY G.J., DEWDNEY P.E., BURGESS T.A., WILLIS A.G., LIGHTFOOT J.F., JENNESS T., LEECH J., MATTHEWS H.E., HEYER M. and POULTON C.J.

Abstract (from CDS):

We present a new large-scale survey of the J = 3-2 12CO emission covering 4.8 deg2 around the Rosette Nebula. The results reveal the complex dynamics of the molecular gas in this region. We identify about 2000 compact gas clumps having a mass distribution given by dN/dMM–1.8, with no dependence of the power-law index on distance from the central O stars. A detailed study of a number of the clumps in the inner region shows that most exhibit velocity gradients in the range 1-3km/s/pc, generally directed away from the exciting nebula. The magnitude of the velocity gradient decreases with distance from the central O stars, and we compare the apparent clump acceleration with a photoionized gas acceleration model. For most clumps outside the central nebula, the model predicts lifetimes of a few 105yr. In one of the most extended of these clumps, however, a near-constant velocity gradient can be measured over 1.7pc, which is difficult to explain with radiatively driven models of clump acceleration.

As well as the individual accelerated clumps, an unresolved limb-brightened rim lies at the interface between the central nebular cavity and the Rosette Molecular Cloud. Extending over 4pc along the edge of the nebula, this region is thought to be at an earlier phase of disruption than the accelerating compact globules.

Blueshifted gas clumps around the nebula are in all cases associated with dark absorbing optical globules, indicating that this material lies in front of the nebula and has been accelerated towards us. Redshifted gas shows little evidence of associated line-of-sight dark clouds, indicating that the dominant bulk molecular gas motion throughout the region is expansion away from the O stars. In addition, we find evidence that many of the clumps lie in a molecular ring, having an expansion velocity of 30km/s and radius 11pc. The dynamical time-scale derived for this structure (∼106yr) is similar to the age of the nebula as a whole (2x106yr).

The J = 3-2/1-0 12CO line ratio in the clumps decreases with radial distance from the exciting O stars, from 1.6 at ∼8pc distance to 0.8 at 20pc. This can be explained by a gradient in the surface temperature of the clumps with distance, and we compare the results with a simple model of surface heating by the central luminous stars.

We identify seven high-velocity molecular flows in the region, with a close correspondence between these flows and embedded young clusters or known young luminous stars. These flows are sufficiently energetic to drive gas turbulence within each cluster, but fall short of the turbulent energy of the Rosette giant molecular cloud by two orders of magnitude.

We find 14 clear examples of association between an embedded young star (as seen by Spitzer at 24µm) and a CO clump in the molecular cloud facing the nebular. The CO morphology indicates that these are photoevaporating circumstellar envelopes. CO clumps without evidence of embedded stars tend to have lower gas velocity gradients. It is suggested that the presence of the young star may extend the lifespan of the externally photoevaporating envelope.


Abstract Copyright: © 2009 The Authors. Journal compilation © 2009 RAS

Journal keyword(s): stars: formation - ISM: globules - ISM: individual: NGC2244

CDS comments: In table 1 : designation ROFN (1 to 7) not used in Simbad.

Simbad objects: 24

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Number of rows : 24

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 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2021 1
2 NAME NGC 2071 IR SFR 05 47 04.4 +00 21 49           ~ 62 0
3 NGC 2071 RNe 05 47 10 +00 18.0           ~ 611 1
4 IRAS 06270+0457 IR 06 29 41.34 +04 55 40.3           ~ 3 0
5 NAME Rosette Nebula HII 06 31 40 +04 57.8           ~ 451 1
6 [PL97] 1 Cl* 06 31 48.1 +04 19 01           ~ 17 2
7 IRAS 06291+0421 IR 06 31 48.48 +04 19 30.7           ~ 27 1
8 NGC 2244 OpC 06 31 55 +04 56.5   5.26 4.8     ~ 566 4
9 HD 46150 Em* 06 31 55.5205503719 +04 56 34.302522479 6.03 6.86 6.73 6.50 6.41 O5V((f))z 375 0
10 HH 871 HH 06 31 57.7 +04 19 12           ~ 3 0
11 HD 46223 Y*O 06 32 09.3066083011 +04 49 24.707398183 6.73 7.50 7.28 6.95 6.79 O4V((f)) 357 0
12 IRAS 06306+0437 IR 06 33 16.212 +04 34 53.04           ~ 26 1
13 [PL97] 2 Cl* 06 33 16.4 +04 34 57           ~ 15 1
14 IRAS 06308+0402 Y*O 06 33 31.1 +04 00 07           ~ 47 1
15 [PL97] 3 OpC 06 33 32.1 +04 00 25           ~ 20 1
16 IRAS 06314+0427 IR 06 34 04.92 +04 25 00.1           ~ 22 1
17 [PL97] 4 Cl* 06 34 05.5 +04 24 54           ~ 16 1
18 RAFGL 961 Y*O 06 34 37.741 +04 12 44.20           ~ 236 1
19 [PL97] 6 Cl* 06 34 38.0 +04 12 44           ~ 18 0
20 NAME Rosette Molecular Cloud MoC 06 34.7 +04 02           ~ 229 0
21 [PL97] 7 Cl* 06 35 30.550 +03 59 00.60           ~ 15 1
22 IRAS 06329+0401 IR 06 35 32.26 +03 58 52.3           ~ 7 1
23 M 16 OpC 18 18 48 -13 48.4   6.58 6.0     ~ 947 2
24 IC 1396 OpC 21 39 00 +57 29.4           ~ 447 1

    Equat.    Gal    SGal    Ecl

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2020.11.29-01:09:14

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