Nov. 18, 2014, 4 p.m.

LGRT 1033 Lecture Area

Riwaj Pokhrel

Title: A HERSCHEL-SPIRE SURVEY OF THE MON R2 GIANT MOLECULAR CLOUD Abstract: We present a far-IR survey of the entire Mon R2 GMC covering 4.30 deg by 4.36 deg, obtained with SPIRE and cross-calibrated with Planck-HFI data for absolute off- set and zero point correction. As the best representation of cold dusty molecular clouds, we fit the far-IR SEDs of each pixel with modified blackbody function. We fixed the dust emissivity, \beta, across all fits with the help of the flux ratio plot and found the most optimal value as 1.8. We studied the nature of distribution of column densities. We found that below 7 × 10^{20} cm^{−2} , the distribution is log-normal in nature whereas above this value, the distribution takes the power-law form. We performed an algorithmic extraction of nested structures from the col- umn density map using the python software package, astrodendro, and found the presence of structures with a variety of aspect ratios. We examined the impact of different fundamental gas configurations (sphere, sheet, filament) on the critical mass and free-fall times derived from our data. We studied the radial profile of filaments and found that the outer density profile takes a power-law form with a shallower slope than for an isothermal filament in equilibrium, suggesting that these filaments are unstable to further collapse.