Star-gas correlations


Correlation between the mass surface densities of star and gas in the Mon R2 GMC. For stars, entire population of class 1 and class 2 young stellar objects are taken into account.

The star formation laws in molecular clouds have been studied for over half a century now. However, there is still no precise answer. The rate of star formation depends on the availability of dense gas in clouds. Thus, a relation is expected between natal gas and the rate of star formation. Studies in nearby galaxies report different values for this dependence. However, those galaxies are so far away that directly forming protostars can’t be probed and indirect measures are used to study star formation. The big advantage of studying this in nearby molecular clouds is that we can directly probe the forming protostars. I study such correlations in nearby molecular clouds to understand better the dependence of star formation on available gas mass. For the clouds where all the stars are formed around the same time (e.g. Mon R2), I find that the correlation between star and gas densities is very tight, suggesting more clustered stars are formed in the regions with higher gas density, and vice versa. For the clouds where stars are formed in different epochs of time (e.g. Cygnus X), there is a high scatter in the relation. However, I still find a tight correlation if I include only recently formed protostars, suggesting that the evolution of stars play a huge role in constraining star-gas correlations.