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
Zhang, Yong; Tej, Anandmayee; Soam, Archana; Eswaraiah, Chakali; Lee, Chang Won; Liu, Hong-Li; Liu, Tie; Xie, Jinjin; Li, Guang-Xing; Li, Shanghuo; Zhang, Qizhou; Wang, Ke; Yue, Nannan; Qin, Sheng-Li; Garay, Guido; Tatematsu, Ken'ichi; Ren, Zhiyuan; Dewangan, Lokesh; Fuller, Gary A.; Stutz, Amelia M.; Juvela, Mika; Goldsmith, Paul F.; Tang, Mengyao; Zhang, Chao; Xu, Feng-Wei; Bronfman, Leonardo; Toth, L. Viktor; Liu, Xunchuan; Issac, Namitha; Luo, Qiuyi; Baug, Tapas; Vázquez-Semadeni, Enrique; Gómez, Gilberto C.; Liu, Meizhu; Wang, Chao; Jiao, Wenyu; Wu, Yue-Fang; Zhang, Siju; Zhou, Jianwen; Liu, Rong
China, United States, Finland, India, Chile, Germany, Mexico, Japan, Hungary, United Kingdom, South Korea, Republic of Korea
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.