Volume 547, November 2012
|Number of page(s)||7|
|Section||Interstellar and circumstellar matter|
|Published online||29 October 2012|
The molecular clump towards the eastern border of SNR G18.8+0.3
Instituto de Astronomía y Física del Espacio (IAFE),
CC 67, Suc. 28,
2 FADU – Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
3 CBC – Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
4 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
Received: 5 July 2012
Accepted: 7 September 2012
Aims. The eastern border of the SNR G18.8+0.3, close to an HII regions complex, is a very interesting region for studying the molecular gas that it is probably in contact with the supernova remnant (SNR) shock front.
Methods. We observed this region using the Atacama Submillimeter Telescope Experiment (ASTE) in the 12CO J = 3–2, 13CO J = 3–2, HCO + J = 4–3, and CS J = 7–6 lines with an angular resolution of 22′′. To complement these observations, we analyzed infrared, submillimeter, and radio continuum archival data.
Results. In this work, we clearly show that the radio continuum “protrusion” that was earlier thought to belong to the SNR is an HII region complex that is deeply embedded in a molecular clump. The new molecular observations reveal that this dense clump, belonging to an extended molecular cloud that surrounds the SNR’s southeast border, is not physically in contact with SNR G18.8+0.3, suggesting that the SNR shock front has not yet reached it or that they may be located at different distances. We found some young stellar objects embedded in the molecular clump, suggesting that their formation should be approximately coeval with the SN explosion.
Key words: ISM: clouds / ISM: supernova remnants / stars: formation
© ESO, 2012
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