{
  "id": "2312.13605",
  "version": "v1",
  "published": "2023-12-21T06:46:22.000Z",
  "updated": "2023-12-21T06:46:22.000Z",
  "title": "UOCS-XII. A study of open cluster NGC 6940 using UVIT/AstroSat: cluster properties and exotic populations",
  "authors": [
    "Anju Panthi",
    "Kaushar Vaidya"
  ],
  "categories": [
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "We study an open cluster NGC 6940 using \\textit{AstroSat}/UVIT data and other archival data. This is an intermediate age cluster ($\\sim$ 1 Gyr), located at about 770 pc distance, harboring several exotic populations apart from normal single and binary stars. We identify members of this cluster using a machine learning algorithm, ML-MOC and identify 492 members, including 1 blue straggler star (BSS), 2 yellow straggler stars (YSS), 11 blue lurker (BL) candidates, and 2 red clump (RC) stars. The cluster shows the effect of mass segregation, with massive stars segregated the most into the cluster, followed by the equal-mass binary members and the single low mass stars. We report the presence of an extended main-sequence turn-off (eMSTO) feature in this cluster and suggest that the age spread may be a contributing factor behind it. However, the effect of stellar rotation, and the dust absorption needs to be examined more comprehensively with a larger fraction of MSTO stars. All the sixteen sources mentioned above have a counterpart in the UVIT/F169M filter. In order to characterize them, we construct multi-wavelength spectral energy distributions (SEDs) of 14 of these objects having no nearby sources within 3\". The BSS is successfully fitted with a single-component SED. We find that three BLs, two YSS, and one RC star have UV excess greater than 50$\\%$ and successfully fit two-component SEDs having hot companions. The parameters derived from the SEDs imply that the hot companions of BLs and the RC star are low-mass and normal-mass white dwarfs, whereas the hot companions of YSS are likely to be subdwarf B (sdB) stars. We suggest that at least 6 out of 14 stars ($\\sim$42 $\\%$) are formed via mass transfer and/or merger pathways.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-12-21T06:46:22.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "open cluster ngc",
      "exotic populations",
      "cluster properties",
      "hot companions",
      "construct multi-wavelength spectral energy distributions"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}