Accretion Flows or Outflow Cavities? Uncovering the Gas Dynamics around Lupus 3-MMS

Abstract

Understanding how material accretes onto the rotationally supported disk from the surrounding envelope of gas and dust in the youngest protostellar systems is important for describing how disks are formed. Magnetohydrodynamic simulations of magnetized, turbulent disk formation usually show spiral-like streams of material (accretion flows) connecting the envelope to the disk. However, accretion flows in these early stages of protostellar formation still remain poorly characterized due to their low intensity and possibly some extended structures are disregarded as being part of the outflow cavity. We use ALMA archival data of a young Class 0 protostar, Lupus 3-MMS, to uncover four extended accretion flow-like structures in C 18 O that follow the edges of the outflows. We make various types of position-velocity cuts to compare with the outflows and find the extended structures are not consistent with the outflow emission, but rather more consistent with a simple infall model. We then use a dendrogram algorithm to isolate five sub-structures in position-position-velocity space. Four out of the five sub-structures fit well (>95%) with our simple infall model, with specific angular momenta between 2.7 − 6.9 × 10 −4 km s −1 pc and mass-infall rates of 0.5 − 1.1 × 10 −6 M yr −1 . Better characterization of the physical structure in the supposed "outflow-cavities" is important to disentangle the true outflow cavities and accretion flows.

A cold accretion flow onto one component of a multiple protostellar system

“…In embedded protostellar systems, these structures have been traced in continuum at scales below 100 AU (e.g., Alves et al 2019), from scales of a few hundred to a few thousand AU in HCO + (Tokuda et al 2014) or in CO (Takakuwa et al 2017;Tokuda et al 2018;Alves et al 2020;Thieme et al 2021), and in HC 3 N at scales of 10 000 AU (Pineda et al 2020). These detections are for close binary systems (separations <100 AU; Takakuwa et al 2017;Alves et al 2019;Pineda et al 2020) or single protostellar sources (Tokuda et al 2014(Tokuda et al , 2018Alves et al 2020;Thieme et al 2021). Furthermore, an extended structure in dust and gas, a so-called tail structure, is observed toward a Class II system A&A 658, A53 (2022) (Akiyama et al 2019;Ginski et al 2021).…”