The Jeans mass and the origin of the knee in the IMF

Astronomy and Astrophysics – Astrophysics

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

6 pages, 4 figures, MNRAS in press

Scientific paper

10.1111/j.1365-2966.2006.10214.x

We use numerical simulations of the fragmentation of a 1000 solar mass molecular cloud and the formation of a stellar cluster to study how the initial conditions for star formation affect the resulting initial mass function (IMF). In particular, we are interested in the relation between the thermal Jeans mass in a cloud and the knee of the initial mass function, i.e. the mass separating the region with a flat IMF slope from that typified by a steeper, Salpeter-like, slope. In three isothermal simulations with M_J=1 solar mass, M_J=2 solar masses and M_J=5 solar masses, the number of stars formed, at comparable dynamical times, scales roughly with the number of initial Jeans masses in the cloud. The mean stellar mass also increases (though less than linearly) with the initial Jeans mass in the cloud. It is found that the IMF in each case displays a prominent knee, located roughly at the mass scale of the initial Jeans mass. Thus clouds with higher initial Jeans masses produce IMFs which are shallow to higher masses. This implies that a universal IMF requires a physical mechanism that sets the Jeans mass to be near 1 solar mass. Simulations including a barotropic equation of state as suggested by Larson, with cooling at low densities followed by gentle heating at higher densities, are able to produce realistic IMFs with the knee located at approximately 1 solar mass, even with an initial M_J=5 solar masses. We therefore suggest that the observed universality of the IMF in the local Universe does not require any fine tuning of the initial conditions in star forming clouds but is instead imprinted by details of the cooling physics of the collapsing gas.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

The Jeans mass and the origin of the knee in the IMF 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 The Jeans mass and the origin of the knee in the IMF, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Jeans mass and the origin of the knee in the IMF will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-79740

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.