Simulations Involving Spherical Collapse in Star Forming Regions of Molecular Gas Clouds
Mentor 1
Phil Chang
Location
Union Wisconsin Room
Start Date
24-4-2015 10:30 AM
End Date
24-4-2015 11:45 AM
Description
The formation of stars remains an outstanding unsolved problem in astrophysics. Central to this problem is that the rate of star formation that is observed in galaxies is much slower than one would naively expect. In addition, observation of star forming regions in our galaxy show that the rate of star formation varies wildly from environment to environment. To help understand the relation between star formation on small scales and star formation on a galactic scale, we focus on understanding how gas collapses under its own self-gravity. Recent work by Murray and Chang (2015) suggests that the collapse on small scales is driven by the competition between turbulent pressure and gravity. They showed that their analytic results match those of large-scale numerical simulations. To check some of the predictions of the Murray and Chang (2015) model, we use the adaptive mesh refinement code FLASH version 4.0.1 (Fryxell et al. 2000; Dubey et al. 2008) to model the collapse of gas on very small scales. Starting with a root grid of 128^3, we use as many as 10 levels of refinement to achieve an effective resolution of 128000^3, nearly three orders of magnitude better linear resolution. We find that the predictions of Murray and Chang (2015) are reproduced for some collapsing regions, but not all. In particular, the radial infall and turbulent velocities show signs of the aforementioned competition between turbulence and gravity. At very small scales, we find the emergence of Keplerian disks support by angular momentum, a result that was overlooked by Murray and Chang (2015). We discuss the implications of this work for star formation studies.
Simulations Involving Spherical Collapse in Star Forming Regions of Molecular Gas Clouds
Union Wisconsin Room
The formation of stars remains an outstanding unsolved problem in astrophysics. Central to this problem is that the rate of star formation that is observed in galaxies is much slower than one would naively expect. In addition, observation of star forming regions in our galaxy show that the rate of star formation varies wildly from environment to environment. To help understand the relation between star formation on small scales and star formation on a galactic scale, we focus on understanding how gas collapses under its own self-gravity. Recent work by Murray and Chang (2015) suggests that the collapse on small scales is driven by the competition between turbulent pressure and gravity. They showed that their analytic results match those of large-scale numerical simulations. To check some of the predictions of the Murray and Chang (2015) model, we use the adaptive mesh refinement code FLASH version 4.0.1 (Fryxell et al. 2000; Dubey et al. 2008) to model the collapse of gas on very small scales. Starting with a root grid of 128^3, we use as many as 10 levels of refinement to achieve an effective resolution of 128000^3, nearly three orders of magnitude better linear resolution. We find that the predictions of Murray and Chang (2015) are reproduced for some collapsing regions, but not all. In particular, the radial infall and turbulent velocities show signs of the aforementioned competition between turbulence and gravity. At very small scales, we find the emergence of Keplerian disks support by angular momentum, a result that was overlooked by Murray and Chang (2015). We discuss the implications of this work for star formation studies.
