Astronomy and Astrophysics Seminars
ALMA reveals molecular cloud N55 in the Large Magellanic Cloud as a site of massive star formation
by Dr. Naslim Neelamkodan (ALMA Regional Center, NAOJ, Japan)
Friday, March 24, 2017
from
to
(Asia/Kolkata)
at DAA ( A269 )
at DAA ( A269 )
TIFR
Description |
The star-forming region, N55, in the Large Magellanic Cloud galaxy is observed with Atacama Large Millimeter Array (ALMA) in band 3 and band 6 receivers, at spectral windows centered at 12CO(1-0), 13CO(1-0), 12CO(2-1) and 13CO(2-1). We examine the molecular clump properties such as size, velocity dispersion, mass, and their association to star formation. This region is less extreme than the well studied 30Doradus or N159 environments. We choose this cloud based on our infrared spectroscopic and photometric observations with Spitzer and Hershel space telescopes. With infrared spectrograph on Spitzer, we have detected the H2 rotational transitions at 28.2 and 17.1 micron in N55. The clumpy and filamentary structures of H2 emission in N55 spatially resemble the distribution of polycyclic aromatic hydrocarbon (PAH) emission traced by Spitzer InfraRed Array Camera (IRAC) 8.0 micron as well as the dust emission traced by Herschel Photodetector Array Camera and Spectrometer (PACS) 100 micron. Our goal is to determine how (dis-)similar the N55 clumps are from Milky Way clouds and 30Doradus. We find that massive clumps are associated with high and intermediate-mass YSOs. The size-linewidth relation of N55 shows a similar trend as in many Milky Way quiescent clouds. The trend shows a power law relation with the index of 0.5+/-0.05. This result suggests that N55 clouds are gravitationally bound and the effect of any external pressure may be negligible. We derive a CO-to-H2 conversion factor, Xco, twice the value of Galactic Clouds. The clump mass function in N55 shows a similar trend as that found in Milky Way clouds and 30Doradus in the LMC. Our studies show that the mass spectrum index is not dependent on the environments sampled. This study confirms a universal behavior of the clump mass function at smaller spatial scales in a sub-solar metallicity galaxy. |