Protostellar Jet and Outflow in the Collapsing Cloud Core

Masahiro N. Machida, Shu ichiro Inutsuka, Tomoaki Matsumoto

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)


Using three-dimensional resistive MHD nested grid simulations, we investigate the driving mechanism of outflows and jets in star formation process. Starting with a Bonnor-Ebert isothermal cloud rotating in a uniform magnetic field, we calculated cloud evolution from the molecular cloud core (nc = 104 cm − 3, r = 4. 6 ×104 AU) to the stellar core (nc = 1022 cm − 3, r ∼ 1R), where nc and r denote the central density and radius of each object, respectively. In the collapsing cloud core, we found two distinct flows: Low-velocity outflows (∼ 5 km) with a wide opening angle, driven from the adiabatic core, and high-velocity jets (∼ 30 km) with good collimation, driven from the protostar. High-velocity jets are enclosed by low-velocity outflow. The difference in the degree of collimation between the two flows is caused by the strength of the magnetic field and configuration of the magnetic field lines. The magnetic field around an adiabatic core is strong and has an hourglass configuration; therefore, the low-velocity outflow from the adiabatic core are driven mainly by the magnetocentrifugal mechanism and guided by the hourglass-like field lines. In contrast, the magnetic field around the protostar is weak and has a straight configuration owing to Ohmic dissipation in the high-density gas region. Therefore, high-velocity jet from the protostar are driven mainly by the magnetic pressure gradient force and guided by straight field lines. Differing depth of the gravitational potential between the adiabatic core and the protostar cause the difference of the flow speed. Low-velocity outflows correspond to the observed molecular outflows, while high-velocity jets correspond to the observed optical jets. We suggest that the protostellar outflow and the jet are driven by different cores, rather than that the outflow being entrained by the jet.

Original languageEnglish
Title of host publicationProtostellar Jets in Context
EditorsKanaris Tsinganos, Tom Ray, Matthias Stute
PublisherSpringer Science and Business Media B.V.
Number of pages6
ISBN (Print)9783642005756
Publication statusPublished - 2009
Externally publishedYes
EventConference on Protostellar Jets in Context, 2008 - Island of Rhodes, Greece
Duration: Jul 7 2008Jul 12 2008

Publication series

NameAstrophysics and Space Science Proceedings
ISSN (Print)1570-6591
ISSN (Electronic)1570-6605


ConferenceConference on Protostellar Jets in Context, 2008
CityIsland of Rhodes

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy
  • Computer Science Applications
  • Spectroscopy
  • Space and Planetary Science
  • Nuclear and High Energy Physics


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