Astronomy and Astrophysics – Astrophysics
Scientific paper
2001-02-07
Mon.Not.Roy.Astron.Soc. 324 (2001) 573
Astronomy and Astrophysics
Astrophysics
8 pages, 4 figures, MNRAS in press
Scientific paper
10.1046/j.1365-8711.2001.04311.x
We present a simple physical mechanism that can account for the observed stellar mass spectrum for masses $\ms \simgreat 0.5 \solm$. The model depends solely on the competitive accretion that occurs in stellar clusters where each star's accretion rate depends on the local gas density and the square of the accretion radius. In a stellar cluster, there are two different regimes depending on whether the gas or the stars dominate the gravitational potential. When the cluster is dominated by cold gas, the accretion radius is given by a tidal-lobe radius. This occurs as the cluster collapses towards a $\rho\propto R^{-2}$ distribution. Accretion in this regime results in a mass spectrum with an asymptotic limit of $\gamma=-3/2$ (where Salpeter is $\gamma=-2.35$). Once the stars dominate the potential and are virialised, which occurs first in the cluster core, the accretion radius is the Bondi-Hoyle radius. The resultant mass spectrum has an asymptotic limit of $\gamma=-2$ with slightly steeper slopes ($\gamma\approx-2.5$) if the stars are already mass-segr egated. Simulations of accretion onto clusters containing 1000 stars show that as expected, the low-mass stars accumulate the majority of their masses during the gas dominated phase whereas the high-mass stars accumulate the majority of their massed during the stellar dominated phase. This results in a mass spectrum with a relatively shallow $\gamma\approx 3/2$ power-law for low-mass stars and a steeper, power-law for high-mass stars $ -2.5\simless\gamma\le -2$. This competitive accretion model also results in a mass segregated cluster.
Bate Matthew R.
Bonnell Ian A.
Clarke Catherine J.
Pringle James E.
No associations
LandOfFree
Accretion in stellar clusters and 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 Accretion in stellar clusters and the IMF, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Accretion in stellar clusters and the IMF will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-461370