Formation Process of the Circumstellar Disk: Long-term Simulations in the Main Accretion Phase of Star Formation

Details Formation Process of the Circumstellar Disk: Long-term Simulations in the Main Accretion Phase of Star Formation Formation Process of the Circumstellar Disk: Long-term Simulations in the Main Accretion Phase of Star Formation

2010-01-09

arxiv.org/abs/1001.1404v1

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

32 pages, 11 figures, Submitted to ApJ. For high resolution figures see http://www2-tap.scphys.kyoto-u.ac.jp/~machidam/astro

Scientific paper

The formation and evolution of the circumstellar disk in unmagnetized molecular clouds is investigated using three-dimensional hydrodynamic simulations from the prestellar core until the end of the main accretion phase. In collapsing clouds, the first (adiabatic) core with a size of ~10AU forms prior to the formation of the protostar. At its formation, the first core has a thick disk-like structure, and is mainly supported by the thermal pressure. After the protostar formation, it decreases the thickness gradually, and becomes supported by the centrifugal force. We found that the first core is a precursor of the circumstellar disk. This indicates that the circumstellar disk is formed before the protostar formation with a size of ~10AU, which means that no protoplanetary disk smaller than <10AU exists. Reflecting the thermodynamics of the collapsing gas, at the protostar formation epoch, the circumstellar disk has a mass of ~0.01-0.1 solar mass, while the protostar has a mass of ~10^-3 solar mass. Thus, just after the protostar formation, the circumstellar disk is about 10-100 times more massive than the protostar. Even in the main accretion phase that lasts for ~10^5yr, the circumstellar disk mass dominates the protostellar mass. Such a massive disk is unstable to gravitational instability, and tends to show fragmentation. Our calculations indicate that the planet or brown-dwarf mass object may form in the circumstellar disk in the main accretion phase. In addition, the mass accretion rate onto the protostar shows strong time variability that is caused by the perturbation of proto-planets and/or the spiral arms in the circumstellar disk. Such variability provides a useful signature for detecting the planet-sized companion in the circumstellar disk around very young protostars.

Affiliated with

Also associated with

No associations

Rating

Formation Process of the Circumstellar Disk: Long-term Simulations in the Main Accretion Phase of Star Formation 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 Formation Process of the Circumstellar Disk: Long-term Simulations in the Main Accretion Phase of Star Formation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Formation Process of the Circumstellar Disk: Long-term Simulations in the Main Accretion Phase of Star Formation will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-580380