Formation, orbital and thermal evolution, and survival of planetary-mass clumps in the early phase of circumstellar disc evolution

Yusuke Tsukamoto, Masahiro N. Machida, Shu Ichiro Inutsuka

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)

Abstract

We report the results of our three-dimensional radiation hydrodynamics simulation of collapsing unmagnetized molecular cloud cores. We investigate the formation and evolution of the circumstellar disc and the clumps formed by disc fragmentation. Our simulation shows that disc fragmentation occurs in the early phase of circumstellar disc evolution and many clumps form. The clump can be represented by a polytrope sphere of index n~3 and n ≳ 4 at central temperature Tc ≲ 100K and Tc ≳ 100 K, respectively.We demonstrate, numerically and theoretically, that the maximum mass of the clump, beyond which it inevitably collapses, is~0.03M. The entropy of the clump increases during its evolution, implying that evolution is chiefly determined by mass accretion from the disc rather than by radiative cooling. Although most of the clumps rapidly migrate inward and finally fall on to the protostar, a few clumps remain in the disc. The central density and temperature of the surviving clump rapidly increase and the clump undergoes a second collapse within 1000-2000 years after its formation. In our simulation, three second cores of masses 0.2M, 0.15M and 0.06M formed. These are protostars or brown dwarfs rather than protoplanets. For the clumps to survive as planetary-mass objects, the rapid mass accretion should be prevented by some mechanisms.

Original languageEnglish
Pages (from-to)1667-1673
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume436
Issue number2
DOIs
Publication statusPublished - Dec 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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