Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2009-09-11
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
10 pages; to appear in ApJ
Scientific paper
The timescale for star formation, a measure of how quickly neutral gas is being converted to stars, is considerably longer than typical dynamical timescales associated with a galactic disk. For purposes of modeling galaxy evolution, however, it would be extremely attractive if the star formation timescale were proportional to an easily derived dynamical timescale. We compare estimates of the star formation timescale within nearby galaxies, based on the work of Leroy et al. (2008) and existing BIMA SONG CO data, with three simple forms of the dynamical time: the orbital time, the free-fall time at the midplane density, and the disk Jeans time (the growth time for gravitational instabilities in a disk). When taking into account the gravity of the stellar disk in an approximate way, all three timescales show correlations with the star formation timescale, though none of the correlations can be accurately described as linear. Systematic errors in estimating appropriate gas masses and the stellar velocity dispersion may obscure an underlying correlation, but we focus instead on a model where the timescale for H_2 formation from HI is decoupled from the timescale for star formation from H_2. The Jeans time correlates well with the first of these timescales, but the relationship is still non-linear, and requires a characteristic GMC lifetime that increases toward galaxy centers.
No associations
LandOfFree
On the Timescale for Star Formation in Galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with On the Timescale for Star Formation in Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the Timescale for Star Formation in Galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-428654