由CO谱线观测得到的气盘尺寸：Angular Momentum演化的检验
Gas Disk Sizes from CO Line Observations: A Test of Angular Momentum Evolution
摘要：
磁盘的大小编码了有关其演化的重要信息。结合新的亚毫米波阵列（SMA）观测和阿塔卡马大毫米波阵列（ALMA）的存档数据，我们分析了几个邻近恒星形成区中质量为0.15- 2\，$M_{\odot}$的44颗恒星周围原行星盘的毫米波连续谱和CO发射谱线尺寸。从$^{12}$ CO谱线发射测量的尺寸范围为50至1000 μ m。这个范围可以用具有不同$α$值（主要是$10^{-4}-10^{-3}$）的粘性演化模型和/或初始条件的扩展来解释。大多数盘的CO尺寸也与直接去除盘角动量的MHD风模型一致，但是需要非常大的初始盘尺寸来解释样品中非常扩展的CO盘。由于在该样品中没有观测到恒星年龄在0.5- 20.00万年之间的CO尺寸演化，因此确定盘演化的主导机制将需要更完整的样品，用于更年轻和更演化的系统。我们发现，CO发射普遍更延长比连续发射的平均因子为$2.9\pm1.2$。CO与连续谱的比值与恒星质量、毫米连续谱光度或子结构的性质无关。在该样品中，GO Tau盘具有最长的CO发射，具有7.6的极端CO与连续体尺寸比。另外7个样品中的磁盘显示高尺寸比（$\gtrsim4$），我们解释为明显的迹象，大量的径向漂移。
英文摘要：
The size of a disk encodes important information about its evolution. Combining new Submillimeter Array (SMA) observations with archival Atacama Large Millimeter Array (ALMA) data, we analyze mm continuum and CO emission line sizes for a sample of 44 protoplanetary disks around stars with masses of 0.15--2\,$M_{\odot}$ in several nearby star-forming regions. Sizes measured from $^{12}$CO line emission span from 50 to 1000\,au. This range could be explained by viscous evolution models with different $α$ values (mostly of $10^{-4}-10^{-3}$) and/or a spread of initial conditions. The CO sizes for most disks are also consistent with MHD wind models that directly remove disk angular momentum, but very large initial disk sizes would be required to account for the very extended CO disks in the sample. As no CO size evolution is observed across stellar ages of 0.5--20\,Myr in this sample, determining the dominant mechanism of disk evolution will require a more complete sample for both younger and more evolved systems. We find that the CO emission is universally more extended than the continuum emission by an average factor of $2.9\pm1.2$. The ratio of the CO to continuum sizes does not show any trend with stellar mass, mm continuum luminosity, or the properties of substructures. The GO Tau disk has the most extended CO emission in this sample, with an extreme CO to continuum size ratio of 7.6. Seven additional disks in the sample show high size ratios ($\gtrsim4$) that we interpret as clear signs of substantial radial drift.
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。
