Discovery of an accretion streamer and a slow wide-angle outflow around FU Orionis
A. S. Hales, A. Gupta, D. Ruiz-Rodriguez, J. P. Williams, S. Perez, L. Cieza, C. Gonzalez-Ruilova, J. E. Pineda, A. Santamaria-Miranda, J. Tobin, P. Weber, Z. Zhu, A. Zurlo
We present ALMA 12-m, 7-m & Total Power (TP) Array observations of the FU Orionis outbursting system, covering spatial scales ranging from 160 to 25,000 au. The high-resolution interferometric data reveals an elongated $^{12}$CO(2-1) feature previously observed at lower resolution in $^{12}$CO(3-2). Kinematic modeling indicates that this feature can be interpreted as an accretion streamer feeding the binary system. The mass infall rate provided by the streamer is significantly lower than the typical stellar accretion rates (even in quiescent states), suggesting that this streamer alone is not massive enough to sustain the enhanced accretion rates characteristic of the outbursting class prototype. The observed streamer may not be directly linked to the current outburst but rather a remnant of a previous, more massive streamer that may have contributed enough to the disk mass to render it unstable and trigger FU Ori's outburst. The new data detects, for the first time, a vast, slow-moving carbon monoxide molecular outflow emerging from this object. To accurately assess the outflow properties (mass, momentum, kinetic energy), we employed $^{13}$CO(2-1) data to correct for optical depth effects. The analysis indicates that the outflow corresponds to swept-up material not associated with the current outburst, similar to slow-molecular outflows observed around other FUor and Class I protostellar objects.
The protostar FU Orionis may not be bursting: dramatic accretion suppression in embedded young eccentric binaries
Heidelberg Institute for Theoretical Studies（海德堡理论研究所）；Research School of Astronomy & Astrophysics, Australian National University（澳大利亚国立大学天体物理与天文研究学院）
A Streamer Driving Misalignment in the Circumtriple Disk of GW Ori
University of Florida（佛罗里达大学）；Columbia University（哥伦比亚大学）；Max-Planck Institute for Astronomy (MPIA)（马克斯·普朗克天文学研究所）；University of Galway（戈尔韦大学）；Queen Mary University of London（伦敦玛丽女王大学）
研究发现 GW Ori 三星系统的流致最外侧尘埃环对准偏差约 3°，可能是其盘结构错位的驱动因素，该流或源于邦迪-霍伊尔吸积，GW Ori 仍与诞生星云保持动力学联系。
Planck cold clumps in the $λ$ Orionis complex: I. Discovery of an extremely young Class 0 protostellar object and a proto-brown dwarf candidate in a bright rimmed clump PGCC G192.32-11.88
我们正在用地面望远镜对$λ$ Orionis复合体中的普朗克银河系冷团（PGCC）进行一系列观测，以系统地研究恒星反馈的影响。在PGCC G192.32-11.88的特殊情况下，我们发现了一个非常年轻的0类原恒星天体（G192 N）和一个原棕矮星候选天体（G192 S）。G192 N和G192 S位于一个受重力束缚的亮边团块中。在CO同位素谱线发射中观察到的速度和温度梯度表明PGCC G192.32-11.88受到外部加热和压缩。与猎户座复合体中其他年轻的0级源（例如PACS亮红源（PBRs））相比，G192 N可能具有最低的热光度（$\sim0.8$ L $_{\sun}$）和吸积速率（6.3 $\times10^{-7}$ M $_{\sun}$ ~yr $^{-1}$）。它的内部光度（$0.21\pm0.01$ L $_{\sun}$）和外流速度（$\sim$ 14 km~s $^{-1}$）比第一流体静力学核心（FHSC）的预测值稍大。G192 N可能是最年轻的0级源之一，比FHSC稍微进化。考虑到它的低内部光度（$0.08\pm0.01$ L $_{\odot}$）和吸积速率（2.8 $\times10^{-8}$ M $_{\sun}$ ~yr $^{-1}$），G192 S是一颗理想的原棕矮星候选者。PGCC G192.32-11.88中的恒星形成效率（$\sim$ …
Characterizing the physical and chemical properties of the Class I protostellar system Oph-IRS 44. Binarity, infalling streamers, and accretion shocks
European Southern Observatory（欧洲南方天文台）；Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）；Leiden University（莱顿大学）；University of Michigan（密歇根大学）；National Tsing Hua University（国立清华大学）；RIKEN Cluster for Pioneering Research（理化学研究所前沿研究集群）；University of Copenhagen（哥本哈根大学）
Early Planet Formation in Embedded Disks (eDisk). VII. Keplerian Disk, Disk Substructure, and Accretion Streamers in the Class 0 Protostar IRAS 16544-1604 in CB 68
基于 ALMA eDisk 项目对 CB 68 中 0 类原恒星 IRAS 16544-1604 的观测，研究揭示了其具有耀展和非轴对称结构的 ~30 au 开普勒旋转盘，并发现了连接盘面的 ~1500 au 吸积流及伴随的吸积激波与外流。
