Accelerating infall and rotational spin-up in the hot molecular core G31.41+0.31-猫眼课题宝

DOI：

10.1051/0004-6361/201832811

发表时间：

2018-03

期刊：

Astronomy & Astrophysics

影响因子：

6.5

通讯作者：

中科院分区：

物理与天体物理2区

文献类型：

作者：

M. Beltr'an;R. Cesaroni;V. Rivilla;'A. S'anchez-Monge;L. Moscadelli;A. Ahmadi;V. Allen;H. Beuther;S. Etoka;D. Galli;R. Galv'an-Madrid;C. Goddi;K. Johnston;A. Kolligan;R. Kuiper;M. Kumar;L. Maud;J. Mottram;T. Peters;P. Schilke;L. Testi;F. V. D. Tak;C. F. I. A. D. Arcetri;I. Institut;U. Koln;M. F. Astronomy;Heidelberg;K. Institute;U. Groningen;S. I. F. S. Research-S.-I.-F.-S.-Research-152214217;Groningen;J. B. C. F. Astrophysics;Manchester;Instituto de Radioastronom'ia y Astrof'isica Morelia-Instituto-de-Radioastronom'ia-y-Astrof'isica-2230372164;Department of AstrophysicsIMAPP;R. University;A. Observatory;Leiden University;S. O. Physics;Astronomy;Leeds;UK Astronomy Technology Centre;Royal Observatory of Edinburgh;I. O. Astronomy;Astrophysics;U. Tubingen;I. D. A. E. C. D. Espacco-I.-D.-A.-E.-C.-D.-Espacco-88742463;U. Porto;Centre for Gravitational Astrophysics;U. Hertfordshire;L. Observatory;M. F. Astrophysik;Garching;Eső

作为我们寻找高质量天体周围恒星圆盘的努力的一部分，我们观测到了著名的核心G31.41+0.31，其ALMA为1.4 mm，角分辨率为~0.‘22(~1700Au)。沙尘连续发射被分解为两个核心，即主核心和东北核心。主核发射较强，化学丰度较高，直径约5300 Au，与两个自由-自由连续源有关。主核在尘埃连续发射中看起来没有特征和均匀，没有任何碎裂的迹象。CH3CN和CH3OCHO的每一次跃迁，无论是基态激发的还是振动激发的，以及CH3CN同位素的每一次跃迁，都显示出明显的NE-SW方向的速度梯度，速度随着距离中心的距离线性增加，这与固体的旋转一致。然而，当比较具有不同上能级能量的跃迁的速度场时，自转速度随着跃迁能量的增加而增加，这表明自转速度向中心加速。朝向尘埃连续谱峰的谱线显示出倒置的P-天鹅座剖面，这支持了核心中存在坠落。落差速度随着跃迁能量的增加而增加，这表明落差正在向地核中心加速，这与引力坍塌是一致的。尽管主核的外观是整体的，但红移吸收的存在，中心嵌入的两个自由源的存在，以及旋转自旋的存在，都与由于角动量守恒而经历了坠落和差异旋转的不稳定核的碎裂相一致。因此，对这种整体形态最可能的解释是，尘埃排放的大不透明度阻止了对核心中任何不均匀的检测。

As part of our effort to search for circumstellar disks around high-mass stellar objects, we observed the well-known core G31.41 +0.31 with ALMA at 1.4 mm with an angular resolution of ~0.′′22 (~1700 au). The dust continuum emission has been resolved into two cores namely Main and NE. The Main core, which has the stronger emission and is the more chemically rich, has a diameter of ~5300 au, and is associated with two free-free continuum sources. The Main core looks featureless and homogeneous in dust continuum emission and does not present any hint of fragmentation. Each transition of CH3CN and CH3OCHO, both ground and vibrationally excited, as well as those of CH3CN isotopologues, shows a clear velocity gradient along the NE–SW direction, with velocity linearly increasing with distance from the center, consistent with solid-body rotation. However, when comparing the velocity field of transitions with different upper level energies, the rotation velocity increases with increasing energy of the transition, which suggests that the rotation speeds up toward the center. Spectral lines towardtoward the dust continuum peak show an inverse P-Cygni profile that supports the existence of infall in the core. The infall velocity increases with the energy of the transition suggesting that the infall is accelerating toward the center of the core, consistent with gravitational collapse. Despite the monolithic appearance of the Main core, the presence of red-shifted absorption, the existence of two embedded free-free sources at the center, and the rotational spin-up are consistent with an unstable core undergoing fragmentation with infall and differential rotation due to conservation of angular momentum. Therefore, the most likely explanation for the monolithic morphology is that the large opacity of the dust emission prevents the detection of any inhomogeneity in the core.

Accelerating infall and rotational spin-up in the hot molecular core G31.41+0.31

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