{
  "id": "2308.07559",
  "version": "v1",
  "published": "2023-08-15T04:00:54.000Z",
  "updated": "2023-08-15T04:00:54.000Z",
  "title": "Giant molecular cloud G18.1-0.3+51 associated with HII regions and supernova remnant in the 3-kpc expanding ring",
  "authors": [
    "Yoshiaki Sofue"
  ],
  "comment": "To appear in MNRAS, 14 pages, 15 figures",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Analyzing the high-resolution CO-line survey of the Galactic plane with the Nobeyama 45-m telescope (FUGIN), we show that the star-forming complex G18.15-0.30+51 (G18) at radial velocity of 51 \\kms is {a tight triple association of a giant molecular cloud (GMC), HII regions, and a supernova remnant (SNR).} The kinematical distance of G18 is determined to be $d=3.9\\pm 0.2$ kpc for near solution for circular rotation, $12\\pm 0.2$ kpc for far solution, or $d=6.1\\pm 0.1$, if it is in the 3-kpc expanding ring. The HI-line absorption of radio continuum from the HII regions constrains the distance to $5.6 \\lesssim d_{\\rm SNR}\\le 7.6$ kpc. The $\\Sigma-D$ (radio brightness-diameter) relation yields the distance to the SNR of $d_{\\rm SNR}=10.1^{+11.5}_{-4.7}$ kpc, allowing for a minimum distance of 5.4 kpc. From these we uniquely determined the distance of G18 to be $6.07\\pm 0.13$ kpc in the 3-kpc expanding ring with the SNR being physically associated. The molecular mass of the GMC is estimated to be $M_{\\rm mol}\\sim 3\\times 10^5 M_\\odot$. The ratio of Virial to luminous molecular masses is greater than unity in the central region and decreases outward to $\\lesssim 0.2$ at the cloud edge, indicating that the central region is dynamic, while the entire cloud is stable. We discuss the origin of the G18 triple system and propose a sustainable GMC model with continuous star formation.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-08-15T04:00:54.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "giant molecular cloud",
      "supernova remnant",
      "expanding ring",
      "central region",
      "molecular mass"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}