A new method to derive kinetic temperatures in Molecular Clouds
Supervisor: Alvaro Hacar
Contact information: alvaro.hacar@univie.ac.at
Expected duration: 9 months
Project description & Goals:
Characterizing the thermal structure in Molecular Clouds is one of the current challenges in ISM studies. In recent times, Herschel has provided detailed maps of the (effective) dust temperatures Tdust in the solar neighbourhood. However, these dust temperatures Tdust may differ from the gas kinetic temperatures TK due to the density dependence of the gas-to-dust thermal coupling. Obtaining a direct measurement of these TK values is essential to derive fundamental properties of the ISM such as its thermal pressure or chemical composition. Traditionally, these measurements have been based on traces such as NH3. However, the use of these classical tracers is limited into a small density and temperature ranges. Our group has developed a new observational technique to determine the gas temperatures using the temperature sensitive HCN/HNC line ratio (Hacar et al 2020). Applying this novel technique this project will characterize the different gas and dust temperatures in different star-forming regions with different environmental conditions (e.g. w/o feedback). Our goal is to investigate the physical conditions for the gas-to-dust coupling.
Working plan & Milestones (including final thesis):
- Literature and introduction to the methodology
- Obtain HCN/HNC TK maps in different SF regions
- Compare these HCN/HNC temperature maps with their corresponding Herschel Tdust maps
- Investigate the gas-to-dust thermal coupling in MCs
- Compare with externally irradiated + PDR models (optional)
- Write Master Thesis
Requirements / special skills: Basic background in star formation is preferred
References:
Goldsmith 2001: https://ui.adsabs.harvard.edu/abs/2001ApJ...557..736G/abstract
Hacar, Bosman, & van Dischoeck 2020: https://ui.adsabs.harvard.edu/abs/2020A%26A...635A...4H/abstract