Young, blue, and isolated stellar systems in the Virgo Cluster. I. 2-D Optical spectroscopy

TL;DR

This study uses 2-D optical spectroscopy to analyze isolated low-mass star-forming regions in the Virgo Cluster, revealing their origin from gas stripped from larger galaxies and suggesting a new class of stellar systems.

Contribution

It provides the first detailed spectroscopic analysis of candidate isolated stellar systems in the Virgo Cluster, linking their properties to gas stripping processes.

Findings

Four candidates are confirmed as Virgo members with gas stripped from larger galaxies.

All confirmed candidates have higher metallicity than expected for their stellar mass.

These objects resemble the prototype system SECCO 1, indicating a new class of stellar systems.

Abstract

We use panoramic optical spectroscopy obtained with MUSE@VLT to investigate the nature of five candidate extremely isolated low-mass star forming regions (Blue Candidates, BCs hereafter) toward the Virgo cluster of galaxies. Four of the five (BC1, BC3, BC4, BC5) are found to host several HII regions and to have radial velocities fully compatible with being part of the Virgo cluster. All the confirmed candidates have mean metallicity significantly in excess of that expected from their stellar mass, indicating that they originated from gas stripped from larger galaxies. In summary, these four candidates share the properties of the prototype system SECCO 1, suggesting the possible emergence of a new class of stellar systems, intimately linked to the complex duty cycle of gas within clusters of galaxies. A thorough discussion on the nature and evolution of these objects is presented in a companion paper, where the results obtained here from MUSE data are complemented with Hubble Space Telescope (optical) and Very Large Array (HI) observations.