Young, Blue, and Isolated Stellar Systems in the Virgo Cluster. I. 2D Optical Spectroscopy

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.We use panoramic optical spectroscopy obtained with the Very Large Telescope/MUSE to investigate the nature of five candidate extremely isolated low-mass star-forming regions (Blue Candidates; hereafter, BCs) toward the Virgo cluster of galaxies. Four of the five (BC1, BC3, BC4, and BC5) are found to host several H ii 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 of the nature and evolution of these objects is presented in a companion paper, where the results obtained here from the MUSE data are complemented with Hubble Space Telescope (optical) and Very Large Array (Hi) observations. © 2022. The Author(s). Published by the American Astronomical Society.M.B. acknowledges the financial support of INAF—OAS Bologna, through the Ob. F. 1.05.01.01—Ricerca di Base funds. D.J.S. acknowledges support from NSF grants AST-1821967 and 1813708. A.K. acknowledges financial support from the State Agency for Research of the Spanish Ministry of Science, Innovation and Universities, through the "Center of Excellence Severo Ochoa" awarded to the Instituto de Astrofísica de Andalucía (SEV-2017-0709), and through the grant POSTDOC_21_00845, financed from budgetary program 54a Scientific Research and Innovation of the Economic Transformation, Industry, Knowledge and Universities Council of the Regional Government of Andalusia. E.A.K.A. is supported by the WISE research program, which is financed by the Dutch Research Council (NWO). R.R.M. gratefully acknowledges support from the ANID BASAL project FB210003. K.S. acknowledges support from the Natural Sciences and Engineering Research Council of Canada (NSERC). B.M.P. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST2001663. J.M.C., J.F., and J.L.I. are supported by NSF/AST grant 2009894. G.B. acknowledges support from the Agencia Estatal de Investigación del Ministerio de Ciencia en Innovación (AEI-MICIN) and the European Regional Development Fund (ERDF), under grants CEX2019-000920-S and PID2020-118778GB-I00/10.13039/501100011033.Peer reviewe