Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 2B001

THE FORMATION AND DYNAMICS OF SELF-GRAVITATING HIGH-DENSITY AREAS IN MASSIVE CIRCUMSTELLAR DISCS

Snytnikov, Valeriy (Boreskov Institute of Catalysis SBRAS, Novosibirsk State University)
Stoyanovskya, Olga (Boreskov Institute of Catalysis SBRAS, Novosibirsk State University)
Stadnichenko, Olga (Boreskov Institute of Catalysis SBRAS, Novosibirsk State University)
Markelova, Tamara (Boreskov Institute of Catalysis SBRAS, Novosibirsk State University)

Abstract:
Planetary formation processes are commonly considered for low-massive and medium massive protoplanetary discs. We investigate processes in massive discs, being motivated by the following statements. In chemical composition of gas-dust disc medium after hydrogen, helium and water the organic compounds form the large portion. Presence of the organic compounds changes collision dynamics of the solids in the discs and their upper size defined by aggregation. The inorganic compounds of the solids are active in chemical reactions of Fisher-Tropsh synthesis, which decreases under favorable conditions the concentration of CO, so the ratio CO/H2 can be decreased for the circumstellar discs with respect to molecular cloud. So when the mass of the disc is estimated by means of CO concentration, it can be underestimated. Massive self-gravitating disc where gravitational instability development could take place can be formed as a result of Jeans instability in molecular cloud and following fragment collapse. We simulated gas flow and dynamics of metre-sized solid clusters in massive circumstellar disc. Our computer simulations demonstrated that solitary clumps of gas and boulders can be formed due to the development of a two-phase gravitational instability. This instability revealed a so-called ímutual influence effectí in the protoplanetary disc, where the dynamics of the system were determined by the collisionless collective motion of a low-mass subdisc composed of primary solids. In the regimes when global structure formation is determined by the gaseous component of the disc such structures can capture boulders. We found that the efficiency of such solidís capturing correlate with initial velocity dispersion of solids: the less initial dispersion is, the more proportion of solids is kept during the movement of the density peak. Possible role of such self-gravitating objects in planetary formation scenarios will be discussed in the report.

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