期刊
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF AUSTRALIA
卷 25, 期 3, 页码 129-137出版社
CSIRO PUBLISHING
DOI: 10.1071/AS07054
关键词
ISM : evolution; ISM : molecules; galaxies : ISM; galaxies : individual (Large magellanic cloud); radio lines : ISM; galaxies : magellanic clouds
资金
- Commonwealth of Australia
With the ATNF Mopra telescope we are performing a survey in the (CO)-C-12(1-0) line to map the molecular gas in the Large Magellanic Cloud. For some regions we also obtained interferometric maps of the high density gas tracers HCO+ and HCN with the Australia Telescope Compact Array. Here we discuss the properties of the elongated molecular complex that stretches about 2 kpc southward from 30 Doradus. Our data suggest that the complex, which we refer to as the 'molecular ridge', is not a coherent feature but consists of many smaller clumps that share the same formation history. Likely triggers of molecular-cloud formation are shocks and shearing forces that are present in the surrounding south-eastern HI overdensity region, a region influenced by strong ram pressure and tidal forces. The molecular ridge is at the western edge of the the overdensity region where a bifurcated velocity structure transitions into a single disk velocity component. We find that the (CO)-C-12(1-0) and HIemission peaks in the molecular ridge are typically near each other but never coincide. A likely explanation is the conversion of warmer, low-opacity HI to colder, high-opacity HI from which H-2 subsequently forms. On smaller scales we find that very dense molecular gas, as traced by interferometric HCO+ and HCN maps, is associated with star formation along shocked filaments and with rims of expanding shell-like structures, both created by feedback from massive stars.
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