FAUST – VIII. The protostellar disc of VLA 1623–2417W and its streamers imaged by ALMA

Abstract

More than 50 % of solar-mass stars form in multiple systems. It is therefore crucial to investigate how multiplicity affects the star and planet formation processes at the protostellar stage. We report continuum and C$^$O (2–1) observations of the VLA 1623-2417 protostellar system at 50 au angular resolution as part of the ALMA Large Program FAUST. The 1.3 mm continuum probes the disks of VLA 1623A, B, and W, and the circumbinary disk of the A1+A2 binary. The C18O emission reveals, for the first time, the gas in the disk-envelope of VLA 1623W. We estimate the dynamical mass of VLA 1623W, Mdyn = 0.45 ± 0.08 M⊙, and the mass of its disk, Mdisk ∼ 6 × 10−3 M⊙. C18O also reveals streamers that extend up to 1000 au, spatially and kinematically connecting the envelope and outflow cavities of the A1+A2+B system with the disk of VLA 1623W. The presence of the streamers, as well as the spatial (∼1300 au) and velocity (∼2.2 km/s) offset of VLA 1623W suggest that either sources W and A+B formed in different cores, interacting between them, or that source W has been ejected from the VLA 1623 multiple system during its formation. In the latter case, the streamers may funnel material from the envelope and cavities of VLA 1623AB onto VLA 1623W, thus concurring to set its final mass and chemical content.

An ALMA-resolved View of 7000 au Protostellar Gas Ring around the Class I Source CrA-IRS 2 as a Possible Sign of Magnetic Flux Advection

“…The lack of observational confidence to discuss the interchange instability was due to the ring's incomplete distribution. Such imperfect ring structures are also found in other Class 0 objects, such as VLA 1623 (Mercimek et al 2023) and IRAS 16293-2422 (Murillo et al 2022). The observational examples cited here bear some resemblance to the features of the IRS 2 gas ring, providing value for revisiting their origin, although individual detailed studies are needed.…”

Discovery of Asymmetric Spike-like Structures of the 10 au Disk around the Very Low-luminosity Protostar Embedded in the Taurus Dense Core MC 27/L1521F with ALMA

“…These arc-like structures, as incomplete rings, probably correspond to streamers in numerous protostellar targets. While further individual studies are necessary to discuss the origins of such structures observationally, arc-like structures or rings spanning a few thousand astronomical units, similar to those discovered in MC 27, have been frequently identified in Class 0/I targets (e.g., Alves et al 2020;Murillo et al 2022;Mercimek et al 2023;Sai et al 2023;Sharma et al 2023). The possibility that these are parts of rings formed through interchange instability cannot be dismissed in favor of a simple accretion interpretation.…”

Finding Substructures in Protostellar Disks in Ophiuchus

“…VLA 1623 West was previously thought to have close to no envelope (Murillo et al 2013;Kirk et al 2017;Michel et al 2022). The edge-on nature of VLA 1623 West complicates the description of an envelope, but recent results from Mercimek et al (2023) estimate it to be 0.04 M e , and they also find accretion streamers adding material onto the protostar and disk system. In addition, the ambiguous disks IRS 44 and Elias 29 each need the extra Gaussian envelope component.…”

“…consider it to be an ejected source from the triple system, whereas the source could also be an unrelated object or noncoeval with A and B(Murillo et al 2016). It is nevertheless found to be spatially and kinematically connected with A and B through accretion streamers(Mercimek et al 2023).…”