2013A&A...559A..31B


Query : 2013A&A...559A..31B

2013A&A...559A..31B - Astronomy and Astrophysics, volume 559A, 31-31 (2013/11-1)

High-resolution radio emission from RCW 49/Westerlund 2.

BENAGLIA P., KORIBALSKI B., PERI C.S., MARTI J., SANCHEZ-SUTIL J.R., DOUGHERTY S.M. and NORIEGA-CRESPO A.

Abstract (from CDS):

The HII region RCW 49 and its ionizing cluster form an extensive, complex region that has been widely studied at infrared (IR) and optical wavelengths. The Molonglo 843MHz and Australia Telescope Compact Array data at 1.4 and 2.4GHz showed two shells. Recent high-resolution IR imaging revealed a complex dust structure and ongoing star formation. New high-bandwidth and high-resolution data of the RCW 49 field have been obtained to survey the radio emission at arcsec scale and investigate the small-scale features and nature of the HII region. Radio observations were collected with the new 2-GHz bandwidth receivers and the CABB correlator of the Australia Telescope Compact Array [ATCA], at 5.5 and 9.0GHz. In addition, archival observations at 1.4 and 2.4GHz have been re-reduced and re-analyzed in conjunction with observations in the optical, IR, X-ray, and gamma-ray regimes. The new 2-GHz bandwidth data result in the most detailed radio continuum images of RCW 49 to date. The radio emission closely mimics the near-IR emission observed by Spitzer, showing pillars and filaments. The brightest continuum emission comes from the region known as the bridge. The overall flattish spectral index is typically consistent with a free-free emission mechanism. However, hints of nonthermal components are also present in the bridge. An interesting jet-like structure surrounded by a bubble feature whose nature is still unclear has been discovered close to the Westerlund 2 core. Two apparent bow shocks and a number of discrete sources have been detected as well in the surroundings of RCW 49. In addition, we also report on and discuss the possible detection of a hydrogen recombination line. The radio results support an association between the cm continuum and molecular emission. The detection of the radio recombination line kinematically favors a RCW 49 distance of 6-7kpc. If the negative spectral indices measured at the bridge should be confirmed to be caused by synchrotron emission, we propose a scenario where high-energy emission could be produced. Finally, the newly discovered jet-like structure appears to be an intriguing source that deserves a detailed study by itself.

Abstract Copyright:

Journal keyword(s): stars: winds, outflows - ISM: individual objects: RCW 49 - open clusters and associations: individual: Westerlund 2 - radio continuum: ISM - gamma rays: stars

Nomenclature: Fig. 4, Table 2: [BKP2013] a (Nos a-c, e-f), [BKP2013] ddN (Nos dd, dd1-dd2).

Simbad objects: 30

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Number of rows : 30
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 TYC 8608-1017-1 * 10 22 21.4365506472 -57 35 57.061928148   11.25 10.48     ~ 1 0
2 SSTGLMC G284.0764-00.4322 * 10 22 23.0523381648 -57 44 28.084235424           O6V(~)~ 8 0
3 [BKP2013] c Rad 10 22 28.36 -57 35 30.9           ~ 1 0
4 [BKP2013] f Rad 10 22 33.58 -57 56 20.9           ~ 1 0
5 TYC 8608-366-1 * 10 22 35.2144448688 -57 56 03.655603176   12.50 12.74     ~ 1 0
6 [BKP2013] e Rad 10 22 53.82 -57 50 46.1           ~ 1 0
7 TYC 8608-1463-1 * 10 22 58.7334472272 -57 50 49.432673328   12.35 12.07     ~ 1 0
8 PSR J1023-5746 Psr 10 23 02.388 -57 46 09.86           ~ 54 0
9 FGES J1023.3-5747 gam 10 23 15.18313 -57 46 34.7840           ~ 56 0
10 [BKP2013] b Rad 10 23 17.70 -57 36 12.4           ~ 1 0
11 2E 1021.5-5720 X 10 23 22.5 -57 35 42           ~ 4 0
12 CXO J102323.3-573749 X 10 23 23.3 -57 37 49           ~ 1 0
13 V* V712 Car EB* 10 23 58.0126366512 -57 45 48.937268268 15.466 15.473 13.5 12.6   O3If*/WN6+O3If*/WN6 163 1
14 Cl Westerlund 2 OpC 10 23 58.1 -57 45 49           ~ 329 0
15 Cl* Westerlund 2 MSP 188 * 10 24 01.258 -57 45 30.86   14.60 13.32     O3V+O5.5 11 0
16 Cl Westerlund 2 5 * 10 24 02.4404730984 -57 44 36.147162768 14.149 14.514 13.155 12.2   O5/5.5V/III(f) 26 0
17 2MASS J10240306-5748356 * 10 24 03.0657646440 -57 48 35.645154660           O9V 8 0
18 [KC97c] G284.3-00.3 HII 10 24 08.91360 -57 47 14.9820           ~ 7 0
19 GUM 29 HII 10 24 14.6 -57 46 58           ~ 204 0
20 WR 20b WR* 10 24 18.3978418584 -57 48 29.776921704     13.7 12.0   WN6ha 54 0
21 2FGL J1023.5-5749c Bz? 10 24 20 -57 57.1           ~ 14 0
22 UCAC2 6537809 Em* 10 24 39.1832377656 -57 45 21.247877520       14.2   OB 10 0
23 [BKP2013] dd2 Rad 10 24 53.89 -57 48 52.2           ~ 1 0
24 [TFT2007] 463 Y*? 10 24 54.56 -57 48 42.9           ~ 2 0
25 [BKP2013] dd1 Rad 10 24 54.61 +57 48 42.9           ~ 1 0
26 [BKP2013] a Rad 10 25 20.40 -57 40 43.3           ~ 1 0
27 IRAS 10236-5723 IR 10 25 28.6 -57 39 09           ~ 1 0
28 [KC97c] G284.6-00.2 HII 10 26 23.3 -57 48 01           ~ 4 0
29 ICRF J104742.9-621714 QSO 10 47 42.95229991 -62 17 14.6339246   19.99       ~ 38 0
30 ICRF J193925.0-634245 Sy2 19 39 25.0245304992 -63 42 45.640373400   18.87 18.37 17.64   ~ 1137 1

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2023.01.27-18:39:47

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