ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions – XV. Steady accretion from global collapse to core feeding in massive hub-filament system SDC335
Fengwei Xu, Ke Wang, Tie Liu, P. F. Goldsmith, Qizhou Zhang, M. Juvela, Hongli Liu, Sheng‐Li Qin, Guang-Xing Li, Anandmayee Tej, Guido Garay, L. Bronfman, Shanghuo Li, Yuefang Wu, Gilberto C. Gómez, Enrique Vazquez‐Semadeni, Ken’ichi Tatematsu, Zhiyuan Ren, Yong Zhang, L. Viktor Tóth, Xunchuan Liu, Nannan Yue, Siju Zhang, Tapas Baug, Namitha Issac, Amelia M. Stutz, Meizhu Liu, G. A. Fuller, Mengyao Tang, Chao Zhang, L. K. Dewangan, Chang Won Lee, Jianwen Zhou, Jinjin Xie, Wenyu Jiao, Chao Wang, Rong Liu, Qiuyi Luo, Archana Soam, Chakali Eswaraiah
Abstract
ABSTRACT We present ALMA Band-3/7 observations towards ‘the Heart’ of a massive hub-filament system (HFS) SDC335, to investigate its fragmentation and accretion. At a resolution of ∼0.03 pc, 3 mm continuum emission resolves two massive dense cores MM1 and MM2, with $383(^{\scriptscriptstyle +234}_{\scriptscriptstyle -120})$ M⊙ (10–24 % mass of ‘the Heart’) and $74(^{\scriptscriptstyle +47}_{\scriptscriptstyle -24})$ M⊙, respectively. With a resolution down to 0.01 pc, 0.87 mm continuum emission shows MM1 further fragments into six condensations and multi-transition lines of H2CS provide temperature estimation. The relation between separation and mass of condensations at a scale of 0.01 pc favors turbulent Jeans fragmentation where the turbulence seems to be scale-free rather than scale-dependent. We use the H13CO+ J = 1 − 0 emission line to resolve the complex gas motion inside ‘the Heart’ in position-position-velocity space. We identify four major gas streams connected to large-scale filaments, inheriting the anti-clockwise spiral pattern. Along these streams, gas feeds the central massive core MM1. Assuming an inclination angle of 45(± 15)° and a H13CO+ abundance of 5(± 3) × 10−11, the total mass infall rate is estimated to be 2.40(± 0.78) × 10−3 M⊙ yr−1, numerically consistent with the accretion rates derived from the clump-scale spherical infall model and the core-scale outflows. The consistency suggests a continuous, near steady-state, and efficient accretion from global collapse, therefore ensuring core feeding. Our comprehensive study of SDC335 showcases the detailed gas kinematics in a prototypical massive infalling clump, and calls for further systematic and statistical studies in a large sample.