The Thermal Regulation of Gravitational Instabilities in Protoplanetary Disks. II. Extended Simulations with Varied Cooling Rates
The Thermal Regulation of Gravitational Instabilities in Protoplanetary Disks. II. Extended Simulations with Varied Cooling Rates
复制标题
原行星盘中引力不稳定性的热调节。
DOI：
10.1086/426707
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
K. Cai
中科院分区：
文献类型：
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作者：
A. C. Mejía;R. Durisen;M. K. Pickett;K. Cai
为了研究质量传输和行星形成通过引力不稳定性（GI），我们已经扩展了我们的三维流体动力学模拟的原行星盘从以前的文件。我们的目标是确定地理标志的渐近行为，以及它是如何受到不同的恒定冷却时间。最初，Rdisk = 40 Au，Mdisk = 0.07 M偏转，M* = 0.5 M偏转，Qmin = 1.5。持续冷却，tcool = 2 ORP（外旋转周期; 1 ORP = 250年），驱动磁盘不稳定约4 ORP。根据该计算，ORP为23.5。经过12个ORP后，盘进入准稳态，具有持续的非线性不稳定性，外盘的平均Q = 1.44，明确的幂律r（r），以及大致稳定的1.5 × 10-7 M yr-1。输运由全局低阶螺旋模驱动。我们在tcool = 1且ORP为11.2的ORP处重新开始计算。后一种情况也以高方位角分辨率运行。我们发现，较短的冷却时间导致增加的值，更密集和更薄的螺旋结构，和更暴力的动态行为。渐近总内能和方位平均Q（r）对tcool不敏感。碎裂只发生在高分辨率tcool = ORP的情况下;然而，没有碎片存活甚至四分之一的轨道。在GI活跃区和GI不活跃区之间的边界附近出现并生长环状密度增强。我们讨论了这些环的气体巨行星形成的可能影响。
In order to investigate mass transport and planet formation through gravitational instabilities (GIs), we have extended our three-dimensional hydrodynamic simulations of protoplanetary disks from a previous paper. Our goal is to determine the asymptotic behavior of GIs and how it is affected by different constant cooling times. Initially, Rdisk = 40 AU, Mdisk = 0.07 M☉, M* = 0.5 M☉, and Qmin = 1.5. Sustained cooling, with tcool = 2 ORPs (outer rotation periods; 1 ORP ≈ 250 yr), drives the disk to instability in about 4 ORPs. This calculation is followed for 23.5 ORPs. After 12 ORPs, the disk settles into a quasi-steady state with sustained nonlinear instabilities, an average Q = 1.44 over the outer disk, a well-defined power law Σ(r), and a roughly steady ≈ 5 × 10-7 M☉ yr-1. The transport is driven by global low-order spiral modes. We restart the calculation at 11.2 ORPs with tcool = 1 and ORPs. The latter case is also run at high azimuthal resolution. We find that shorter cooling times lead to increased -values, denser and thinner spiral structures, and more violent dynamic behavior. The asymptotic total internal energy and the azimuthally averaged Q(r) are insensitive to tcool. Fragmentation occurs only in the high-resolution tcool = ORP case; however, none of the fragments survive for even a quarter of an orbit. Ringlike density enhancements appear and grow near the boundary between GI-active and GI-inactive regions. We discuss the possible implications of these rings for gas giant planet formation.