2020A&A...639A..93F


Query : 2020A&A...639A..93F

2020A&A...639A..93F - Astronomy and Astrophysics, volume 639A, 93-93 (2020/7-1)

APEX CO observations towards the photodissociation region of RCW 120.

FIGUEIRA M., ZAVAGNO A., BRONFMAN L., RUSSEIL D., FINGER R. and SCHULLER F.

Abstract (from CDS):


Context. The edges of ionized (HII) regions are important sites for the formation of (high-mass) stars. Indeed, at least 30% of the Galactic high-mass-star formation is observed there. The radiative and compressive impact of the HII region could induce star formation at the border following different mechanisms such as the collect and collapse or the radiation-driven implosion (RDI) models and change their properties.
Aims. We aim to study the properties of two zones located in the photo dissociation region (PDR) of the Galactic HII region RCW 120 and discuss them as a function of the physical conditions and young star contents found in both clumps.
Methods. Using the APEX telescope, we mapped two regions of size 1.5'x1.5' toward the most massive clump of RCW 120 hosting young massive sources and toward a clump showing a protrusion inside the HII region and hosting more evolved low-mass sources. The 12CO (J=3-2), 13CO (J=3-2) and C18O (J=3-2) lines observed, together with Herschel data, are used to derive the properties and dynamics of these clumps. We discuss their relation with the hosted star formation.
Results. Assuming local thermodynamic equilibrium, the increase of velocity dispersion and Tex are found toward the center of the maps, where star-formation is observed with Herschel. Furthermore, both regions show supersonic Mach numbers (7 and 17 in average). No substantial information has been gathered about the impact of far ultraviolet radiation on C18O photodissociation at the edges of RCW 120. The fragmentation time needed for CC to be at work is equivalent to the dynamical age of RCW 120 and the properties of region B are in agreement with bright-rimmed clouds.
Conclusions. Although conclusions from this fragmentation model should be taken with caution, it strengthens the fact that, together with evidence of compression, CC might be at work at the edges of RCW 120. Additionally, the clump located at the eastern part of the PDR is a good candidate pre-existing clump where star-formation may be induced by the RDI mechanism.

Abstract Copyright: © ESO 2020

Journal keyword(s): stars: formation - ISM: bubbles - photon-dominated region - ISM: individual objects: RCW 120

Simbad objects: 14

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Number of rows : 14
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 SH 2-212 HII 04 40 37.8 +50 27 40           ~ 98 2
2 NAME Ori A MoC 05 38 -07.1           ~ 2989 0
3 SH 2-233 HII 05 38 31.5 +35 51 19           ~ 66 1
4 NAME Ori B MoC 05 41 43.0 -01 54 44           ~ 1363 0
5 IC 2599 HII 10 37.7 -58 39           ~ 45 2
6 Shk 217 GrG 14 32.3 +31 04           ~ 3 0
7 LBN 005.01+30.90 HII 16 11 00.7 -07 01 36           ~ 8 0
8 V* RT Sco S* 17 03 32.5593710616 -36 55 13.694502792       13.973   S7,2 71 0
9 SH 2-3 HII 17 12.4 -38 28           ~ 204 1
10 NGC 6302 PN 17 13 44.5 -37 06 11           O-rich 794 1
11 SH 2-44 HII 18 16.5 -16 44           ~ 13 0
12 SH 2-39 HII 18 16 52.5 -18 41 50           ~ 15 0
13 SH 2-104 HII 20 17 52.5 +36 49 24           ~ 97 0
14 [RHT2014] GMF G038.1-32.4a ISM 20 57 -10.2           ~ 7 0

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