Second core formation and high-speed jets

Resistive magnetohydrodynamic nested grid simulations

Masahiro Machida, Shu Ichiro Inutsuka, Tomoaki Matsumoto

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

The stellar core formation and high-speed jets driven by the formed core are studied using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud rotating in a uniform magnetic field, we calculate the cloud evolution from the molecular cloud core (n c = 106 cm-3) to the stellar core (nc = 10 23 cm-3), where nc denotes the central density. For comparison, we calculate two models: resistive and ideal MHD models. Both the resistive and ideal models have the same initial condition, but the former includes the dissipation process of magnetic field while the latter does not. The magnetic fluxes in the resistive MHD model are extracted from the first core during 1012 cm-3 < nc < 1016 cm-3 by ohmic dissipation. Magnetic flux density of the formed stellar core (nc = 1020 cm-3) in the resistive MHD model is 2 orders of magnitude smaller than that in ideal MHD model. Since magnetic braking is less effective in the resistive MHD model, a rapidly rotating stellar core (the second core) is formed. After stellar core formation, the magnetic field of the core is largely amplified, and high-speed (≃45 km s-1) jets are driven by the second core, which results in strong mass ejection. A cocoon-like structure around the second core also forms with clear bow shocks.

Original languageEnglish
JournalAstrophysical Journal
Volume647
Issue number2 II
DOIs
Publication statusPublished - Aug 20 2006

Fingerprint

magnetohydrodynamics
stellar cores
grids
high speed
simulation
magnetic field
magnetic flux
dissipation
magnetic fields
ohmic dissipation
braking
cocoon
bows
speed
molecular clouds
ejection
flux density
shock

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Second core formation and high-speed jets : Resistive magnetohydrodynamic nested grid simulations. / Machida, Masahiro; Inutsuka, Shu Ichiro; Matsumoto, Tomoaki.

In: Astrophysical Journal, Vol. 647, No. 2 II, 20.08.2006.

Research output: Contribution to journalArticle

@article{0ceadd8a2dea47129e2bb8b5c019bb46,
title = "Second core formation and high-speed jets: Resistive magnetohydrodynamic nested grid simulations",
abstract = "The stellar core formation and high-speed jets driven by the formed core are studied using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud rotating in a uniform magnetic field, we calculate the cloud evolution from the molecular cloud core (n c = 106 cm-3) to the stellar core (nc = 10 23 cm-3), where nc denotes the central density. For comparison, we calculate two models: resistive and ideal MHD models. Both the resistive and ideal models have the same initial condition, but the former includes the dissipation process of magnetic field while the latter does not. The magnetic fluxes in the resistive MHD model are extracted from the first core during 1012 cm-3 < nc < 1016 cm-3 by ohmic dissipation. Magnetic flux density of the formed stellar core (nc = 1020 cm-3) in the resistive MHD model is 2 orders of magnitude smaller than that in ideal MHD model. Since magnetic braking is less effective in the resistive MHD model, a rapidly rotating stellar core (the second core) is formed. After stellar core formation, the magnetic field of the core is largely amplified, and high-speed (≃45 km s-1) jets are driven by the second core, which results in strong mass ejection. A cocoon-like structure around the second core also forms with clear bow shocks.",
author = "Masahiro Machida and Inutsuka, {Shu Ichiro} and Tomoaki Matsumoto",
year = "2006",
month = "8",
day = "20",
doi = "10.1086/507179",
language = "English",
volume = "647",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2 II",

}

TY - JOUR

T1 - Second core formation and high-speed jets

T2 - Resistive magnetohydrodynamic nested grid simulations

AU - Machida, Masahiro

AU - Inutsuka, Shu Ichiro

AU - Matsumoto, Tomoaki

PY - 2006/8/20

Y1 - 2006/8/20

N2 - The stellar core formation and high-speed jets driven by the formed core are studied using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud rotating in a uniform magnetic field, we calculate the cloud evolution from the molecular cloud core (n c = 106 cm-3) to the stellar core (nc = 10 23 cm-3), where nc denotes the central density. For comparison, we calculate two models: resistive and ideal MHD models. Both the resistive and ideal models have the same initial condition, but the former includes the dissipation process of magnetic field while the latter does not. The magnetic fluxes in the resistive MHD model are extracted from the first core during 1012 cm-3 < nc < 1016 cm-3 by ohmic dissipation. Magnetic flux density of the formed stellar core (nc = 1020 cm-3) in the resistive MHD model is 2 orders of magnitude smaller than that in ideal MHD model. Since magnetic braking is less effective in the resistive MHD model, a rapidly rotating stellar core (the second core) is formed. After stellar core formation, the magnetic field of the core is largely amplified, and high-speed (≃45 km s-1) jets are driven by the second core, which results in strong mass ejection. A cocoon-like structure around the second core also forms with clear bow shocks.

AB - The stellar core formation and high-speed jets driven by the formed core are studied using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud rotating in a uniform magnetic field, we calculate the cloud evolution from the molecular cloud core (n c = 106 cm-3) to the stellar core (nc = 10 23 cm-3), where nc denotes the central density. For comparison, we calculate two models: resistive and ideal MHD models. Both the resistive and ideal models have the same initial condition, but the former includes the dissipation process of magnetic field while the latter does not. The magnetic fluxes in the resistive MHD model are extracted from the first core during 1012 cm-3 < nc < 1016 cm-3 by ohmic dissipation. Magnetic flux density of the formed stellar core (nc = 1020 cm-3) in the resistive MHD model is 2 orders of magnitude smaller than that in ideal MHD model. Since magnetic braking is less effective in the resistive MHD model, a rapidly rotating stellar core (the second core) is formed. After stellar core formation, the magnetic field of the core is largely amplified, and high-speed (≃45 km s-1) jets are driven by the second core, which results in strong mass ejection. A cocoon-like structure around the second core also forms with clear bow shocks.

UR - http://www.scopus.com/inward/record.url?scp=33748543221&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33748543221&partnerID=8YFLogxK

U2 - 10.1086/507179

DO - 10.1086/507179

M3 - Article

VL - 647

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 II

ER -