Filaments, Clumps, and Disks: Investigating the Origins of Star- and Planet-Forming Structures in Molecular Clouds

细丝、团块和圆盘：研究分子云中恒星和行星形成结构的起源

• 批准号: RGPIN-2015-05308
• 负责人: DiFrancesco, James
• 金额: $ 2.55万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=649218
• 关键词: Filaments; Clumps; Disks; Investigating; Origins

Star formation occurs within the densest gas of molecular clouds and planets form out of even denser gas surrounding protostars. In this proposal, I describe plans to exploit the newest observational technologies to determine the origins of substructure in molecular clouds that promote the formation of stars and planets, i.e., filaments, clumps, and disks.  With these projects, Canada will continue its leading role in probing the origins of stars and planets.  These projects will also be undertaken primarily by students under my direct supervision.****The Herschel Space Observatory recently revealed that significant mass in clouds is found in filaments, with the densest examples being the predominant locations of compact pockets of gas, i.e., dense cores, and protostars.   These data indicate the pivotal role of filaments in the star formation process, i.e, providing the conditions from which star formation is most efficient.  Understanding their origins is therefore important, and can be explored with further data of their kinematics. For example, are filaments equilibrium or non-equilibrium structures?  Though some compelling data of a few filamentary regions have been obtained, I propose to use line data of CO, 13CO, and C18O from the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey to probe the kinematics of a wide variety of filaments and through model comparisons determine their dynamical states and origins.****Herschel also revealed that filaments may be implicated in the formation of stellar clusters, as compact pockets of gas more massive than cores that may fragment into tight associations of cores, i.e., clumps, are found at the intersections of filaments.  This arrangement provides an elegant solution to cluster formation, as increased avenues of mass flow are available to grow a specific region to high densities.  Nevertheless, the kinematics of filaments associated with clumps require investigation to determine if this scenario is realistic, e.g., are intersections physical connections of filaments?  I propose to use the U.S. National Radio Astronomy Observatory's Green Bank Telescope (GBT) and Jansky Very Large Array (JVLA) to observe NH3 line emission towards such examples of filament intersection in nearby clouds, specifically those with little to no star formation, and assess their kinematics.***Finally, I propose to address the formation of the flattened structures near protostars from which planets form, i.e., disks.  Observations of disks at their earliest epochs will inform the initial conditions of disk evolution and any subsequent planet formation. Herschel and JCMT, however, do not have the angular resolution to probe such structures.  Instead, I propose to use continuum and (N2H+ and H2D+) line data from the new Atacama Large Millimeter Array (ALMA) to investigate the densities and velocities of dense gas in the centers of cores on the verge or just beyond the star formation event. **** **

恒星的形成发生在分子云中最稠密的气体中，而行星是由原恒星周围更稠密的气体形成的。在这项提议中，我描述了利用最新观测技术来确定分子云中促进恒星形成的子结构起源的计划。通过这些项目，加拿大将继续在探索恒星和行星的起源方面发挥主导作用。这些项目也将主要由我直接领导的学生进行。监督。****赫歇尔太空天文台最近透露，云中存在大量的细丝，最密集的例子是致密气体团的主要位置，即致密核心和原恒星。这些数据表明了关键作用。因此，了解恒星形成过程中的细丝的起源非常重要，并且可以通过其运动学的进一步数据来探索。虽然已经获得了一些丝状区域的一些令人信服的数据，但我建议使用詹姆斯·克拉克·麦克斯韦望远镜 (JCMT) 古尔德带巡天的 CO、13CO 和 C18O 线数据来探测运动学各种细丝的结构，并通过模型比较确定它们的动力学状态和起源。****赫歇尔还揭示，细丝可能与恒星的形成有关在细丝的交叉处发现了团簇，因为比核心更大的紧凑气体袋可能分裂成紧密的核心组合，即团块，这种排列为团簇形成提供了一种优雅的解决方案，因为可以使用增加的质量流途径。然而，要将特定区域生长到高密度，需要研究与团块相关的细丝的运动学，以确定这种情况是否现实，例如，是否存在物理连接的交叉点。我建议使用美国国家射电天文台的 Green Bank Telescope (GBT) 和 Jansky Very Large Array (JVLA) 来观察附近云中此类灯丝交叉的 NH3 线发射，特别是那些几乎没有恒星形成的云，并评估它们的运动学。***最后，我建议解决行星形成的原恒星附近扁平结构的形成问题，即圆盘。对最早时期的圆盘的观测将了解圆盘演化的初始条件以及任何随后的行星形成，但是，赫歇尔和 JCMT 没有角度分辨率来探测这种结构。​相反，我建议使用连续体和（N2H+和）。 H2D+ ）来自新阿塔卡马大型毫米波阵列 (ALMA) 的线数据，用于研究边缘或刚刚的核心中心的致密气体的密度和速度超越恒星形成事件。