时变动态恒星形成率
Time Varying Dynamical Star Formation Rate
摘要：
我们提出了动态恒星形成的数值证据，其中吸积的恒星质量随时间超线性增长，大致为$t^2$。我们进行模拟恒星形成的自引力流体动力学和磁流体动力学湍流是连续驱动的。通过在模拟中打开或关闭气体的自引力，我们证明了自引力是在反馈效应接管之前的早期设定质量吸积速率的主要物理效应，这与顺磁性调节的恒星形成理论相反。我们发现，引力坍缩使恒星周围的密度分布变陡，在对数正态密度概率分布函数上产生幂律尾。此外，我们发现湍流的速度分布扁平内崩溃的区域，改变的尺寸线宽的关系。这种局部平坦化反映了湍流速度在小尺度上的增强，正如速度功率谱的变化所证实的那样。我们的研究结果表明，气体自引力动态地改变了云的密度和速度结构，从而产生了随时间变化的恒星形成率。我们发现，形成恒星的气体中有很大一部分是通过低密度流到达的，而不是通过高密度细丝吸积的。
英文摘要：
We present numerical evidence of dynamic star formation in which the accreted stellar mass grows superlinearly with time, roughly as $t^2$. We perform simulations of star formation in self-gravitating hydrodynamic and magneto-hydrodynamic turbulence that is continuously driven. By turning the self-gravity of the gas in the simulations on or off, we demonstrate that self-gravity is the dominant physical effect setting the mass accretion rate at early times before feedback effects take over, contrary to theories of turbulence-regulated star formation. We find that gravitational collapse steepens the density profile around stars, generating the power-law tail on what is otherwise a lognormal density probability distribution function. Furthermore, we find turbulent velocity profiles to flatten inside collapsing regions, altering the size-linewidth relation. This local flattening reflects enhancements of turbulent velocity on small scales, as verified by changes to the velocity power spectra. Our results indicate that gas self-gravity dynamically alters both density and velocity structures in clouds, giving rise to a time-varying star formation rate. We find that a substantial fraction of the gas that forms stars arrives via low density flows, as opposed to accreting through high density filaments.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
