Massive outflows driven by magnetic effects in star-forming clouds with high mass accretion rates
Massive outflows driven by magnetic effects in star-forming clouds with high mass accretion rates
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DOI：
10.1093/mnras/stx893
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发表时间：
2017-04
影响因子：
4.8
通讯作者：
Yuko Matsushita;M. Machida;Y. Sakurai;T. Hosokawa
中科院分区：
文献类型：
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作者：
Yuko Matsushita;M. Machida;Y. Sakurai;T. Hosokawa
用三维磁流体力学模拟方法研究了磁力驱动风作用下的质量吸积率与质量抛射率之间的关系。用一个热能与引力能之比不同的球状云核来定义初始条件，然后计算几个云核在原恒星形成后约10^4年的流出传播。只有当初始云核的磁能与引力能相当时，质量抛射率和吸积率才是可比的。因此，在强磁化的星云中，较高的质量吸积率自然会产生大量原恒星和大量流出恒星。模拟的流出质量、动量、动能和动量通量与观测结果吻合得很好，表明大质量恒星的形成机制与低质量恒星相同，但需要一个非常强的磁场才能启动大质量外流。
The relation between the mass accretion rate onto the circumstellar disc and the rate of mass ejection by magnetically driven winds is investigated using three-dimensional magnetohydrodynamics simulations. Using a spherical cloud core with a varying ratio of thermal to gravitational energy, which determines the mass accretion rate onto the disc, to define the initial conditions, the outflow propagation for approximately 10^4 yr after protostar formation is then calculated for several cloud cores. The mass ejection rate and accretion rate are comparable only when the magnetic energy of the initial cloud core is comparable to the gravitational energy. Consequently, in strongly magnetised clouds a higher mass accretion rate naturally produces both massive protostars and massive outflows. The simulated outflow mass, momentum, kinetic energy and momentum flux agree well with observations, indicating that massive stars form through the same mechanism as low-mass stars but require a significantly strong magnetic field to launch massive outflows.