# Spectroscopic analysis of VVV CL001 cluster with MUSE

**Authors:** Julio Olivares Carvajal, Manuela Zoccali, Alvaro Rojas-Arriagada, Rodrigo Contreras Ramos, Felipe Gran, Elena Valenti, Javier H. Minniti  
**arXiv:** [2204.06628](https://arxiv.org/abs/2204.06628)  
**Date:** 2022-04-13  
**Summary page:** https://www.summarizepaper.com/en/paper/2204.06628v1/

## Key points

- The Milky Way has a diverse population of globular clusters, including blue and red ones.
- Red clusters are poorly studied due to higher extinction and contamination from field stars.
- A new cluster called VVV CL001 has been confirmed and is the subject of this study.
- Spectroscopic analysis was conducted using MUSE@VLT integral field data.
- 55 potential cluster members were selected based on their radial velocities and proper motions.
- VVV CL001 has a mean radial velocity of -324.9 ± 0.8 km/s and low metallicity ([Fe/H] = -2.04 ± 0.02 dex), indicating it could be a very old cluster in the Galactic bulge.
- VVV CL001's estimated distance is d = 8.23 ± 0.46 kpc and its current position suggests it is most likely a bulge globular cluster.
- These findings provide valuable insight into our understanding of globular clusters in our galaxy while highlighting the need for continued exploration and discovery in this area of research.

## Summary

The Milky Way is home to a diverse population of globular clusters, including blue, metal-poor ones and red, metal-rich ones. However, the latter are poorly studied compared to their blue counterparts due to higher extinction and contamination from field stars. In recent years, a few new clusters have been confirmed, including VVV CL001 which is the subject of this study. Using MUSE@VLT integral field data, the authors conducted a new spectroscopic analysis of VVV CL001. Individual spectra were extracted for stars in the cluster's field and radial velocities were derived through cross-correlation with synthetic templates. Combining these velocities with proper motions from the VVV survey allowed for the selection of 55 potential cluster members whose metallicities were determined using The Cannon public code. The mean radial velocity of VVV CL001 was found to be -324.9 ± 0.8 km/s based on these 55 members, indicating that it could be a very old cluster due to its high velocity and low metallicity ([Fe/H] = -2.04 ± 0.02 dex). The estimated distance places VVV CL001 in the Galactic bulge at d = 8.23 ± 0.46 kpc and its current position and orbital parameters suggest that it is most likely a bulge globular cluster. These findings provide valuable insight into our understanding of globular clusters in our galaxy while highlighting the need for continued exploration and discovery in this area of research.