Event Title

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.

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Apr 24th, 10:30 AM Apr 24th, 11:45 AM

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.