| Abstract : | Star formation process is highly driven by the physical and chemical compositions of its environment, and these conditions vary as a function of Galactocentric distance. The outer part of the Milky Way (lies beyond the Solar circle), the place with negative metallicity gradients, lower gas surface density, and lower interstellar radiation field, is an excellent laboratory to understand the effects of the environment on star formation. Due to presence of low metal abundances the efficiency of gas cooling and dust shielding process decrease significantly, which in turn affects the physical and chemical processes of star-formation. As a result, the star-formation rate and efficiencies are expected to be different in the outer Milky Way. The studies in Outer Milky Way Galaxy bridge the gaps between the galactic and extragalactic star formation studies.
We are leading a large-scale observational survey of star-forming regions in the Outer Galaxy using the 13.7-m telescope from Taeduk Radio Astronomy Observatory, KASI. We intend to understand the role of environmental conditions (such as metallicity and Galactocentric distance) on the outcome of the star formation process such as star formation rate (SFR), star formation efficiency (SFE), and initial mass function (IMF). We are probing these regions with dense molecular line tracers (HCN, HCO+) along with other gas and dust tracers (like extinction from 13CO, 1.1 mm continuum data, far-infrared data from Herschel). We measure the fraction of total line luminosity that arises from the diffuse part of the cloud and the correlations between different tracers of dense gas. A comparative analysis with the same properties of the inner Galaxy clouds will be presented. We will also present the relation between dense gas and star formation activities in the outer Galaxy star forming regions.
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