eCite Digital Repository

Class I methanol masers in the outflow of IRAS 16 547-4247


Voronkov, MA and Brooks, DJ and Sobolev, AM and Ellingsen, SP and Ostrovskii, AB and Caswell, JL, Class I methanol masers in the outflow of IRAS 16 547-4247, Monthly Notices of the Royal Astronomical Society, 373, (1) pp. 411-424. ISSN 0035-8711 (2006) [Refereed Article]

DOI: doi:10.1111/j.1365-2966.2006.11047.x


The Australia Telescope Compact Array (ATCA) has been used to image class I methanol masers at 9.9, 25 (a series from J = 2 to 9), 84, 95 and 104 GHz located in the vicinity of IRAS 16 547-4247 (G343.12-0.06), a luminous young stellar object known to harbour a radio jet. The detected maser emission consists of a cluster of six spots spread over an area of 30 arcsec. Five spots were detected in only the 84- and 95-GHz transitions (for two spots the 84-GHz detection is marginal), while the sixth spot shows activity in all 12 observed transitions. We report the first interferometric observations of the rare 9.9- and 104-GHz masers. It is shown that the spectra contain a very narrow spike (< 0.03 km s -1) and the brightness temperature in these two transitions exceeds 5.3 × 10 7 and 2.0 × 10 4K, respectively. The three most southern maser spots show a clear association with the shocked gas traced by the H 2 2.12-μm emission associated with the radio jet and their velocities are close to that of the molecular core within which the jet is embedded. This fact supports the idea that the class I masers reside in the interface regions of outflows. Comparison with OH masers and infrared data reveals a potential discrepancy in the expected evolutionary state. The presence of the OH masers usually means that the source is evolved, but the infrared data suggest otherwise. The lack of any class II methanol maser emission at 6.7 GHz in the source raises an additional question, Is this source too young or too old to have a 6.7-GHz maser? We argue that both cases are possible and suggest that the evolutionary stage where the class I masers are active, may last longer and start earlier than when the class II masers are active. However, it is currently not possible to reveal the exact evolutionary status of IRAS 16 547-4247. © 2006 RAS.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Ellingsen, SP (Professor Simon Ellingsen)
ID Code:40849
Year Published:2006
Funding Support:Australian Research Council (DP0342478)
Web of Science® Times Cited:72
Deposited By:Physics
Deposited On:2006-08-01
Last Modified:2007-03-21

Repository Staff Only: item control page