Star-forming regions at the periphery of the supershell surrounding the Cyg OB1 association – I. The star cluster vdB 130 and its ambient gas and dust medium

Abstract

Stellar population and the interstellar gas-dust medium in the vicinity of the open star cluster vdB 130 are analysed using optical observations taken with the 6-m telescope of the SAO RAS and the 125-cm telescope of the SAI MSU along with the data of Spitzer and Herschel. Based on proper motions and BV and JHKs 2MASS photometric data, we select additional 36 stars as probable cluster members. Some stars in vdB 130 are classified as B stars. Our estimates of minimum colour excess, apparent distance modulus and the distance are consistent with young age (from 5 to 10 Myrs) of the cluster vdB 130. We suppose the large deviations from the conventional extinction law in the cluster direction, with R V ∼ 4 − 5. The cluster vdB 130 appears to be physically related to the supershell around Cyg OB1, a cometary CO cloud, ionized gas, and regions of infrared emission. There are a few regions of bright midinfrared emission in the vicinity of vdB 130. The largest of them is also visible on Hα and [Sii] emission maps. We suggest that the infrared blobs that coincide in projection with the head of the molecular cloud are Hii regions, excited by the cluster B-stars. Some signatures of a shock front are identified between these IR-bright regions.

Analysis of the kinematic structure of the Cygnus OB1 association

“…For that reason, we didn't exclude this object from the list of clusters inside the Cygnus OB1 association. The cluster vdBergh 130 is located at the upper distance limit (1.8 kpc), according to Sitnik et al (2015), together with IC 4996, which is also located close to the farther border of the association.…”

“…In this field of view, 13 stellar clusters are catalogued. The summarized information about these objects is in Table 2, where the coordinates, the parent OB association, the central RV values given by WEBDA and SIMBAD, respectively, and other cluster parameters like distance, reddening and age taken from four different studies (Loktin, Gerasimenko & Malisheva 2001;Dias et al 2002;Kharchenko et al 2005;Sitnik et al 2015) are shown. The cluster positions are drawn in Fig.…”

“…They said that this cavity represents the early stages of a super bubble produced by the winds and supernovae from spatially distributed massive stars. Sitnik et al (2015) studied the periphery of the super shell surrounding the Cygnus OB1 association and, specifically, the stellar cluster vdBergh 130 and the ISM around it. They concluded that this cluster is physically connected with the super shell around the association, and that there are some ionized regions of bright mid-IR emission in the vicinity of the object.…”

The historical record of massive star formation in Cygnus

“…Some of them, like Cygnus OB1, OB8 and OB9 have been proposed to be part of a single structure (Mel'Nik & Efremov 1995), and it has been suggested that the differences between Cygnus OB2 and OB9 are due to the progression of star formation from lower to higher galactic longitudes rather than to distinct, independent episodes of star formation (Comerón et al 2008;Comerón & Pasquali 2012). Despite large uncertainties and conflicting results, sometimes yielding discrepant distances by factors up to 2 for the same cluster (Straižys et al 2014), most studies yield values in the 1.3-1.8 kpc range for the associations in the area under consideration (e.g., Garmany & Stencel 1992;Hanson 2003;Kharchenko et al 2005;Comerón & Pasquali 2012;Straižys et al 2014Straižys et al , 2019Sitnik et al 2015). Distances to structures in the interestellar medium have been established through evidence of physical links with OB associations, as illustrated by Schneider et al (2007).…”

Star-forming regions at the periphery of the supershell surrounding the Cyg OB1 association - II. ISM kinematics and YSOs in the star cluster vdB 130 region

“…In Sitnik et al (2015) (hereinafter referred to as Paper I) and Tatarnikova et al (2016) we have already partially studied the regions of ongoing star formation located in the supershell and related to the globule family (Arkhipova et al 2013) and the cometary molecular cloud, or pillar . A young (5 − 10 Myr) star cluster vdB 130 (Racine 1968) is observed in the direction of the head of the CO cloud (see square on Fig.…”