标题： HL Tau中多重环结构和隐藏行星的起源：由长期引力不稳定性统一图景 显示英文标题

标题： An Origin of Multiple Ring Structure and Hidden Planets in HL Tau: A Unified Picture by Secular Gravitational Instability

摘要： 近期的 ALMA 观测揭示了在 HL Tau 周围的原行星盘中形成了多个环状结构。 在 HL Tau 的 ALMA 观测之前，对长期引力不稳定性（GI）的理论分析描述了在某些条件下，原行星盘中半径约 100 AU 处可能存在间距为 13 AU 的多个环状结构的可能性。 本文中，我们采用从观测推断出的物理值重新分析了长期 GI 的可行性。 我们得出了长期 GI 最不稳定波长和增长时间尺度的径向分布，并验证了长期 GI 可以形成 HL Tau 中观测到的环状结构。 当盘内区的湍流粘性系数 $\alpha$ 较小时，长期 GI 在整个盘中生长。 因此，在非线性增长之后，由于引力碎裂，行星质量天体应该首先在盘内区形成。 在这种情况下，形成的天体会在 $r$ ~ 10 AU 和 ~ 30 AU 处产生间隙。 因此，HL Tau 中的所有环状结构都可以由长期 GI 形成。 如果这种情景在 HL Tau 中实现，外区对应于长期 GI 最不稳定模式的早期增长阶段，而内区则对应于长期 GI 非线性增长的结果。 因此，这种解释表明我们可能正在见证 HL Tau 中行星形成的开始和结束。 显示英文摘要

摘要： Recent ALMA observation has revealed multiple ring structures formed in a protoplanetary disk around HL Tau. Prior to the ALMA observation of HL Tau, theoretical analysis of secular gravitational instability (GI) described a possible formation of multiple ring structures with separations of 13 AU around a radius of 100 AU in protoplanetary disks under certain conditions. In this article, we reanalyze the viability of secular GI by adopting the physical values inferred from the observations. We derive the radial distributions of the most unstable wavelength and the growth timescale of secular GI and verify that secular GI can form the ring structures observed in HL Tau. When a turbulent viscosity coefficient $\alpha$ remains small in inner region of the disk, secular GI grows in the whole disk. Thus, the formation of planetary mass objects should occur first in the inner region as a result of gravitational fragmentation after the non-linear growth of secular GI. In this case, resulting objects are expected to create the gaps at $r$ ~ 10 AU and ~ 30 AU. As a result, all ring structures in HL Tau can be created by secular GI. If this scenario is realized in HL Tau, the outer region corresponds to the earlier growth phase of the most unstable mode of secular GI, and the inner region corresponds to the outcome of the non-linear growth of secular GI. Therefore, this interpretation suggests that we are possibly witnessing both the beginning and end of planet formation in HL Tau.