Protostars and Planets VI, Heidelberg, July 15-20, 2013
Zooming in on the Formation of Protoplanetary Disks
Nordlund, Åke (Niels Bohr Institute and Centre for Star and Planet Formation, Univ. of Copenhagen)
Küffmeier, Michael (Niels Bohr Institute and Centre for Star and Planet Formation, Univ. of Copenhagen)
Haugbølle, Troels (Centre for Star and Planet Formation, Univ. of Copenhagen)
Padoan, Paolo (ICREA, & ICCC, Univ. of Barcelona)
We use the adaptive mesh refinement computer code RAMSES to model the formation of protoplanetary disks in realistic star formation environments, with resolution scaling over 30 powers of two (about 9 powers of ten), covering a range from outer scales of about 50 pc to inner scales of about 0.01 AU. The simulations are done in three steps, with the first step covering 16 powers of two, following individual star formation in a 50 pc GMC model. In the 2nd step, the neighborhoods of stars with a final system mass of about two solar masses are followed during the accretion process, with a smallest mesh size of 2.5 AU, sufficient to follow the development of the large scale structure of their accretion disks. Finally, a selection of these disks are studied over shorter time intervals, with cell sizes ranging down to 0.01 AU, sufficient to resolve the vertical structure of a significant radius fraction of the disks.
The purpose of this procedure is to characterize the typical properties of accretion disks around solar mass protostars, with as few free parameters as possible, and to gather a statistical sample of such conditions, to quantify the extent of statistical variation of properties. This is a vast improvement over models where initial and boundary conditions have to be chosen arbitrarily. Here, the initial and boundary conditions follow instead from the statistical properties of the interstellar medium, which are reasonably well established, as per for example the “Larson relations” and the “B-n” relation, which provide typical values for the velocity and magnetic field RMS values on different scales.
As a byproduct of this type of modeling, which starts out from a supernova driven interstellar medium, we can follow the transport of short-lived radioactive nuclides (SLRs), from the time of ejection from supernovae and until they become part of the proto-planetary disks. As shown in a recent paper (arXiv: astro-ph/1302.0843) the transport time is on average short enough to be consistent with initial abundance of 26Al in the Solar System derived from cosmochemistry. Of particular interest is to characterize the amount of variation with time of the SLR abundance during the lifetime of PP-disks surrounding solar mass stars.
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