Small scale star formation as revealed by VVVX galactic cluster candidates

TL;DR

This study identifies and analyzes 88 new obscured star cluster candidates in the southern Galactic disk, revealing recent small-scale star formation and confirming some as older open clusters, thereby enhancing understanding of cluster populations.

Contribution

The paper presents the discovery of 88 new clusters and detailed analysis of their properties, expanding the catalog of small and distant clusters in the Galactic disk.

Findings

88 new clusters discovered in the VVVX survey area.

Confirmed three as older, low-mass open clusters.

Identified recent star formation producing small, young clusters.

Abstract

We report a search and analysis of obscured cluster candidates in the "VISTA Variables in the Via Lactea eXtended (VVVX)" ESO Public Survey area encompassing the region between 229.4 < l < 295.2 and -4.3 < b < 4.4 of the southern Galactic disk. We discover and propose 88 new clusters. We improve the completeness of the embedded cluster population in this region, adding small size (linear diameters of 0.2-1.4 pc) and relatively far objects (heliocentric distance between 2 and 4 kpc) to existing catalogues. Nine candidates are proposed to be older open cluster candidates. Three of them (VVVX CL204, 207, 208) have sufficient numbers of well-resolved stellar members to allow us to determine some basic cluster parameters. We confirm their nature as older, low-mass open clusters. Photometric analysis of 15 known clusters shows that they have ages above 20Myr, and masses below 2000Msun: in general, their proper motions follow the motion of the disk. We outline some groups of clusters, most probably formed within the same dust complex. Broadly, our candidates follow the network of filamentary structure in the remaining dust. Thus, in this part of the southern disk of the Galaxy, we have found recent star formation, producing small size and young clusters, in addition to the well known, massive young clusters, including NGC3603, Westerlund2 and the Carina Nebula Complex.