M.Sc. project

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Jes Jørgensenhttp://youngstars.nbi.dk/http://www.nbi.dk/~jeskjshapeimage_2_link_0

The formation processes of low- and high-mass star formation are different in several aspects. Despite much still being unknown about the formation of low- and high-mass stars, this is relatively well-understood when comparing to the formation of the often overlooked intermediate-mass stars (M~10 M_sun). Still, understanding their formation provides an important connection between low- and high-mass star formation.

In this project, focus will be put on understanding the contribution from UV radiation fields caused by nearby massive stars, which can increase the temperature significantly in the outer regions of the protostellar envelopes, largely affecting the chemical processes. By combining data from the Submillimeter Array (SMA) and the Atacama Pathfinder Experiment (APEX), the emission from three isotopologues of carbon monoxide (CO) can be studied, which can be used to constrain extents of the molecular envelope, molecular outflow and external heating regions. These protostars have already been studied in single-dish observations using the James Clerk Maxwell Telescope (JCMT; see Johnstone et al., 2003, A&A, 412, 157), but the interferometric SMA observations will provide high-resolution data, allowing for much more detailed studies of the distribution of the molecular gas. Combining the SMA data with APEX observations will give high-resolution observations also showing the large-scale structures.

The student will learn how to reduce both single-dish and interferometry millimetre data, and acquire a good knowledge of several commonly used data reduction packages. Depending on the interest of the student, the data can also be used in modelling of the heated molecular gas to better establish the physical properties in the protostellar environment (see Jørgensen et al., 2006, A&A, 449, 609).

Formation of protostars in regions of strong UV radiation

Keywords: submillimeter observations and radiation transfer modeling