Effects of Ohmic and ambipolar diffusion on formation and evolution of first cores, protostars, and circumstellar discs

Y. Tsukamoto, K. Iwasaki, S. Okuzumi, M. N. Machida, S. Inutsuka

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49 Citations (Scopus)


We investigate the formation and evolution of a first core, protostar, and circumstellar disc with a three-dimensional non-ideal (including both Ohmic and ambipolar diffusion) radiation magnetohydrodynamics simulation. We found that the magnetic flux is largely removed by magnetic diffusion in the first-core phase and that the plasma β of the centre of the first core becomes large, β > 104. Thus, proper treatment of first-core phase is crucial in investigating the formation of protostar and disc. On the other hand, in an ideal simulation, β ~ 10 at the centre of the first core. The simulations with magnetic diffusion show that the circumstellar disc forms at almost the same time of protostar formation even with a relatively strong initial magnetic field (the value for the initial mass-to-flux ratio of the cloud core relative to the critical value is μ = 4). The disc has a radius of r ~ 1 AU at the protostar formation epoch. We confirm that the disc is rotationally supported. We also show that the disc is massive (Q ~ 1) and that gravitational instability may play an important role in the subsequent disc evolution.

Original languageEnglish
Pages (from-to)278-288
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - Apr 28 2015


All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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