From Gas to Stars in Energetic Environments: Chemistry of Clumps in Giant Molecular Clouds Within the Large Magellanic Cloud
Abstract
We present parsec scale interferometric maps of HCN and HCO^{+} emission from dense gas in the star-forming region 30 Doradus, obtained using the Australia Telescope Compact Array (ATCA). This extreme star-forming region, located in the Large Magellanic Cloud (LMC), is characterized by a very intense ultraviolet ionizing radiation field and sub-solar metallicity, both of which are expected to impact molecular cloud structure. We detect 13 bright, dense clumps within the 30 Doradus-10 giant molecular cloud. Some of the clumps are aligned along a filamentary structure with a characteristic spacing that is consistent with formation via the varicose fluid instability. Our analysis shows that the filament is gravitationally unstable and collapsing to form stars. There is a good correlation between HCO^{+} emission in the filament and signatures of recent star formation activity including H_{2}O masers and young stellar objects (YSOs). We present detailed comparisons of clump properties (masses, linewidths, sizes) in 30Dor-10 to those in other star forming regions of the LMC (N159, N113, N105, N44). Our analysis shows that the 30 Doradus-10 clumps have similar mass but wider linewidths and similar HCN/HCO^{+} (1-0) line ratios as clumps detected in other LMC star-forming regions. Our results suggest that the dense molecular gas clumps in the interior of 30Dor-10 are well-shielded against the intense ionizing field that is present in the 30 Doradus region. We also present preliminary results from follow up observations with the ATCA of a several molecular lines detected from the brightest clumps in 30 Doradus-10, N113 and N159W. The maps cover the following dense gas, photo-dominated regions (PDRs), and shock tracers: HCN, HCO^{+}, C_{2}H, SiO, HNCO, SiS, N_{2}H^{+}, CS, CH_{3}H, CH_{3}CN, {13}^CS, OCS, H_{2}, {34}^CS. These giant molecular clouds have varying radiation fields and energetics. We compare the chemistry within these giant molecular clouds to one another to obtain a detailed understanding on how the changing energetics and radiation fields affect star formation within the LMC.
- Publication:
-
American Astronomical Society Meeting Abstracts #225
- Pub Date:
- January 2015
- Bibcode:
- 2015AAS...22514131A