论文标题
质量较高的质量积聚率失败和延迟的原恒星流出
Failed and delayed protostellar outflows with high mass accretion rates
论文作者
论文摘要
在不同的质量积聚率下，研究了原始流出的演变，$ \ sim10^{ - 5} -10^{ - 2} {\ rm m} _ \ odot $ yr $^{ - 1} $，带有三维磁磁性磁性动态模拟。强大的流出总是出现在用$ b_0 \ gtrsim b _ {\ rm 0，cr} $ = 10^{ - 4}（m _ {\ rm cl}/100 {\ rm m m} _ \ odot）{\ rm g} $ cl cll cl clly中，总是出现强大的流出流。当云的磁场较弱时，流出不会以较高的质量积聚速率迅速发展。在某些情况下，中等磁场的$ B_0 $略小于$ b _ {\ rm 0，Cr} $，流出生长被抑制或延迟，直到插入信封消散，而Protostellar系统周围的RAM压力大大降低。在这样的环境中，仅在后期积聚阶段，流出开始增长并达到较大距离。另一方面，ProtoStellar流出无法发展，并且当巨大的$（\ gtrsim 100 {\ rm m} _ \ odot）$ jinital云被$ b_0 \ b_0 \ sillsim100μ{\ rm g} $忽略时，最终被强RAM压力崩溃。失败的流出产生了一个环形结构，该结构由磁性压力支持并封闭了原恒星和磁盘系统。我们的结果表明，如果所有高质量原恒星都有清晰的流出，则仅在强磁性云中形成高质量恒星。如果我们观察到非常弱或没有在进化的质恒星周围流出，则意味着不一定需要强磁场来形成高质量恒星。在任何情况下，我们都可以从外流的观察结果中限制高质量星形成过程。
The evolution of protostellar outflows is investigated under different mass accretion rates in the range $\sim10^{-5}-10^{-2} {\rm M}_\odot$ yr$^{-1}$ with three-dimensional magnetohydrodynamic simulations. A powerful outflow always appears in strongly magnetized clouds with $B_0 \gtrsim B_{\rm 0, cr}$ $=10^{-4} (M_{\rm cl}/100 {\rm M}_\odot){\rm G}$, where $M_{\rm cl}$ is the cloud mass. When a cloud has a weaker magnetic field, the outflow does not evolve promptly with a high mass accretion rate. In some cases with moderate magnetic fields $B_0$ slightly smaller than $B_{\rm 0,cr}$, the outflow growth is suppressed or delayed until the infalling envelope dissipates and the ram pressure around the protostellar system is significantly reduced. In such an environment, the outflow begins to grow and reaches a large distance only during the late accretion phase. On the other hand, the protostellar outflow fails to evolve and is finally collapsed by the strong ram pressure when a massive $(\gtrsim 100 {\rm M}_\odot)$ initial cloud is weakly magnetized with $B_0 \lesssim 100 μ{\rm G}$. The failed outflow creates a toroidal structure that is supported by magnetic pressure and encloses the protostar and disk system. Our results indicate that high-mass stars form only in strongly magnetized clouds, if all high-mass protostars possess a clear outflow. If we would observe either very weak or no outflow around evolved protostars, it means that strong magnetic fields are not necessarily required for high-mass star formation. In any case, we can constrain the high-mass star formation process from observations of outflows.
