A revision of the vdB 130 cluster stellar content based on GAIA DR2 Data. Interstellar extinction toward the Cyg OB1 supershell

TL;DR

This study refines the stellar membership and distance estimates of the vdB 130 cluster using Gaia DR2 data, revealing its young age and analyzing the interstellar extinction toward the Cyg OB1 supershell.

Contribution

It provides a revised list of cluster members with precise proper motions and parallaxes, and investigates the interstellar extinction law in the region.

Findings

Cluster contains 68 members with consistent proper motions and parallaxes.

Distance to the cluster is estimated at 1.5-2 kpc with 3-7% relative parallax error.

Interstellar extinction increases with distance, following E(B-V) ≈ 0.6×D.

Abstract

Two star-forming regions are studied: the young embedded open cluster vdB 130 and the protocluster neighbourhood observed in the head and tail of the cometary molecular cloud located in the wall of the expanding supershell surrounding the Cyg OB1 association. The GAIA DR2 catalogue is employed to verify the stellar composition of the vdB 130 cluster whose members were earlier selected using the UCAC4 catalogue. The new sample of vdB 130 members contains 68 stars with close proper motions (within 1 mas yr$^{-1}$) and close trigonometric parallaxes (ranging from 0.50 to 0.70 mas). The relative parallax error is shown to increase with distance to objects and depend on their magnitude. At a distance of 1.5-2 kpc it is of about 3-7 per cent and 20-30 per cent for bright and faint stars, respectively. The cluster is not older than ~10 Myr. New spectroscopic and photometric observations carried out on Russian telescopes are combined with GAIA DR2 to search for optical components in the protocluster region - a new starburst. An analysis of 20 stars in the vicinity of the protocluster revealed no concentration of either proper motions or parallaxes. According to spectroscopic, photometric, and trigonometric estimates, the distances to these stars range from 0.4 to 2.5 kpc, and colour excess is shown to increase with a distance D (kpc) in accordance with the law: $E(B-V)\simeq 0.6\times D$ mag.