2008/03/08 by Masahiro N. Machida, Tomoaki Matsumoto, Shu-ichiro Inutsuka +1 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/591074
37 pages, 10 figures, Submitted to ApJ, For high resolution figures, see http://astro3.sci.hokudai.ac.jp/~machida/astro-ph.pdf
arxiv created 2008/03/08 · openalex publication_date 2008/09/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Jet-driving and fragmentation processes in a collapsing primordial cloud are studied using three-dimensional MHD nested grid simulations. Starting from a rotating magnetized spherical cloud with a number density of n c ≃ 10 3 cm −3 , we follow the evolution of the cloud until the adiabatic core (or protostar) formation epoch, n c ≃ 10 22 cm −3 . We calculate 36 models parameterizing the initial magnetic γ 0 and rotational β 0 energies. The evolution of collapsing primordial clouds is characterized by the ratio of the initial rotational energy to the magnetic energy, γ 0 /β 0 . The Lorentz force significantly affects cloud evolution when γ 0 > β 0 , while the centrifugal force dominates the Lorentz force when β 0 > γ 0 . When the cloud rotates rapidly with an angular velocity of Ω 0 > 10 −17 ( n c /10 3 cm −3 ) 2/3 s −1 and β 0 > γ 0 , fragmentation occurs before protostar formation, but no jet appears after protostar formation. On the other hand, when the initial cloud has a magnetic field of B 0 > 10 −9 ( n c /10 3 cm −3 ) 2/3 G and γ 0 > β 0 , a strong jet appears after protostar formation without fragmentation. Our results indicate that Population III protostars frequently show fragmentation and protostellar jets. Population III stars are therefore born as binary or multiple stellar systems; as in present-day star formation, they can drive strong jets that disturb the interstellar medium significantly, and thus they may induce the formation of next-generation stars.