arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新，休息一下吧，周末愉快~~
arXiv 2405.08271astro-ph.SRastro-ph.GA
收藏

恒星形成晚期的云消散与盘风

Cloud Dissipation and Disk Wind in the Late Phase of Star Formation

Masahiro N. Machida, Shantanu Basu

备注：
Accepted for publication in ApJ
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

AI总结：

本研究通过三维非理想磁流体动力学模拟恒星形成晚期过程，揭示了云消散阶段盘风复兴的机制，并估算出盘的消散时标约为10^6年。

摘要：

我们采用三维非理想磁流体动力学开展了恒星与盘形成的长期模拟。该模拟从一颗前恒星云出发，历经星周盘的长期演化，直至原恒星形成后约1.5×10^5年。在主吸积阶段，由于磁制动和磁驱动外流移除角动量的作用，盘的大小≲50 au且几乎没有子结构。当外流冲破云团，导致包层质量迅速下降时，主吸积阶段结束。随后，随着质量吸积率减弱，外流也逐渐变弱。在包层向盘的吸积持续进行的同时，盘逐渐增长，并因引力不稳定性形成瞬时旋臂结构。当包层向盘的吸积终止时，盘趋于稳定，大小达到≳300 au。此外，初始云团质量中约有30%已被外流抛射出去。本研究的一项重要发现是，在包层消散后，风会出现复兴现象，且存在从盘表面持续到模拟结束的质量抛射。这种质量抛射（即盘风）的产生，是因为在这一阶段，盘上下方的磁压显著主导了冲压和热压。利用由盘风估算得到的角动量通量和质量损失率，盘的消散时标约为10^6年。

英文摘要：

We perform a long-term simulation of star and disk formation using three-dimensional non-ideal magnetohydrodynamics. The simulation starts from a prestellar cloud and proceeds through the long-term evolution of the circumstellar disk until $\sim 1.5\times10^5$ yr after protostar formation. The disk has size $\lesssim 50$ au and little substructure in the main accretion phase because of the action of magnetic braking and the magnetically-driven outflow to remove angular momentum. The main accretion phase ends when the outflow breaks out of the cloud, causing the envelope mass to decrease rapidly. The outflow subsequently weakens as the mass accretion rate also weakens. While the envelope-to-disk accretion continues, the disk grows gradually and develops transient spiral structures due to gravitational instability. When the envelope-to-disk accretion ends, the disk becomes stable and reaches a size $\gtrsim 300$ au. In addition, about 30% of the initial cloud mass has been ejected by the outflow. A significant finding of this work is that after the envelope dissipates, a revitalization of the wind occurs, and there is mass ejection from the disk surface that lasts until the end of the simulation. This mass ejection (or disk wind) is generated since the magnetic pressure significantly dominates both the ram pressure and thermal pressure above and below the disk at this stage. Using the angular momentum flux and mass loss rate estimated from the disk wind, the disk dissipation timescale is estimated to be $\sim10^6$ yr.

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。

↑