Astronomy and Astrophysics – Astrophysics
Scientific paper
2003-11-15
Mon.Not.Roy.Astron.Soc. 348 (2004) 1019
Astronomy and Astrophysics
Astrophysics
17 pages, 9 figures; accepted for publication in MNRAS
Scientific paper
10.1111/j.1365-2966.2004.07422.x
The mechanisms which could lead to chemo-thermal instabilities and fragmentation during the formation of primordial protostars are investigated analytically. We introduce approximations for H2 cooling rates bridging the optically thin and thick regimes. These allow us to discuss instabilities up to densities when protostars become optically thick to continuum radiation (n~10^16 cm^-3). During the collapse, instability arises at two different stages: at low density (n~10^8-10^11 cm^-3), it is due to fast 3-body reactions converting H into H2; at high density (n>10^13 cm^-3), it is due to Collisional Induced Emission (CIE). In agreement with the 3D simulations, we find that the instability at low densities cannot lead to fragmentation, because fluctuations do not survive turbulent mixing, and because their growth is slow. The situation at high density is similar. The CIE-induced instability is as weak as the low density one, with similar ratios of growth and dynamical time scales. Fluctuation growth time is longer than free fall time, and fragmentation seems unlikely. One then expects the first stars to be massive, not to form binaries nor harbour planets. Nevertheless, full 3D simulations are required. They could become possible using simplified estimates of radiative transfer effects, which we show to work very well in the 1D case. This indicates that the effects of radiative transfer during the initial stages of formation of primordial protostars can be treated as local corrections to cooling. (Abridged)
Abel Tom
Ripamonti Emanuele
No associations
LandOfFree
Fragmentation and the formation of primordial protostars: the possible role of Collision Induced Emission 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 Fragmentation and the formation of primordial protostars: the possible role of Collision Induced Emission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fragmentation and the formation of primordial protostars: the possible role of Collision Induced Emission will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-586158