# FAUST VIII. The protostellar disk of VLA 1623-2417 W and its streamers imaged by ALMA

**Authors:** S. Mercimek, L. Podio, C. Codella, L. Chahine, A. López-Sepulcre, S. Ohashi, L. Loinard, D. Johnstone, F. Menard, N. Cuello, P. Caselli, J. Zamponi, Y. Aikawa, E. Bianchi, G. Busquet, J. E. Pineda, M. Bouvier, M. De Simone, Y. Zhang, N. Sakai  
**arXiv:** [2303.16257](https://arxiv.org/abs/2303.16257)  
**Date:** 2023-03-28  
**Summary page:** https://www.summarizepaper.com/en/paper/2303.16257v1/

## Key points

- The ALMA Large Program FAUST conducted observations of the VLA 1623-2417 protostellar system
- The system is important to investigate how multiplicity affects star and planet formation processes
- Disks of VLA 1623A, B, and W were observed, as well as the circumbinary disk of the A1+A2 binary
- Gas in the disk-envelope of VLA 1623W was detected through C$^{18}$O emission for the first time
- VLA 1623W has a dynamical mass of $M_{\rm dyn}=0.45\pm0.08$ M$_{\odot}$ with a disk mass of $M_{\rm disk}\sim6\times10^{-3}$ M$_{\odot}$
- Streamers were observed extending up to 1000 au that connect the envelope and outflow cavities of the A1+A2+B system with the disk of VLA 1623W
- These streamers may have funneled material from the envelope and cavities of VLA 1623AB onto VLA 1623W during its formation

## Summary

The ALMA Large Program FAUST has conducted continuum and C$^{18}$O (2-1) observations of the VLA 1623-2417 protostellar system at a 50 au angular resolution. The system is of particular interest as more than 50% of solar-mass stars form in multiple systems, making it crucial to investigate how multiplicity affects the star and planet formation processes at the protostellar stage. The observations reveal the disks of VLA 1623A, B, and W, as well as the circumbinary disk of the A1+A2 binary. Additionally, for the first time, gas in the disk-envelope of VLA 1623W has been detected through C$^{18}$O emission. The dynamical mass of VLA 1623W was estimated to be $M_{\rm dyn}=0.45\pm0.08$ M$_{\odot}$ with a disk mass of $M_{\rm disk}\sim6\times10^{-3}$ M$_{\odot}$. Streamers were also observed extending up to 1000 au that spatially and kinematically connect the envelope and outflow cavities of the A1+A2+B system with the disk of VLA 1623W. This suggests that either sources W and A+B formed in different cores interacting between them or that source W was ejected from the VLA 1623 multiple system during its formation. If ejected during formation, these streamers may have funneled material from the envelope and cavities of VLA 1623AB onto VLA 1623W, thus contributing to setting its final mass and chemical content. The presence of streamers along with a spatial offset ($\sim$1300 au) and velocity offset ($\sim$2.2 km/s) further support this possibility. Overall, these observations provide valuable insights into the formation and evolution of multiple protostellar systems, shedding light on complex processes that shape these systems.