{
  "id": "1706.05664",
  "version": "v1",
  "published": "2017-06-18T14:38:52.000Z",
  "updated": "2017-06-18T14:38:52.000Z",
  "title": "High-mass star formation in Orion possibly triggered by cloud-cloud collision III, NGC2068 and NGC2071",
  "authors": [
    "Daich Tsutsumi",
    "Akio Ohama",
    "Kazuki Okawa",
    "mikito Kohno",
    "Yusuke Hattori",
    "Shinji Fujita",
    "Atsushi Nishimura",
    "Kazufumi Torii",
    "Hidetoshi Sano",
    "Hiroaki Yamamoto",
    "Kengo Tachihara",
    "Yutaka Hasegawa",
    "Kimihiro Kimura",
    "Hideo Ogawa",
    "Yasuo Fukui"
  ],
  "comment": "17peges, 6 figures",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We carried out a molecular line study toward the high-mass star forming regions with reflection nebulae, NGC2068 and NGC2071, in Orion with NANTEN2 in the $^{13} \\rm CO (\\it J\\rm=2-1)$transition. The $^{13} \\rm CO$ distribution shows that there are two velocity components at $8.25$ km s$^{-1}$ and $11.5$ km s$^{-1}$. The blue-shifted \\textcolor{blue}{component} is in the northeast associated with NGC2071, and the red-shifted \\textcolor{blue}{component} is in the southwest associated with NGC2068. The two clouds have a gap of $\\sim 1$ pc in total intensity distribution, suggesting that they are detached at present. A detailed spatial comparison between them indicates that the two show complementary distribution, the blue-shifted \\textcolor{blue}{component} lies toward an intensity depression in the northwest of the red-shifted \\textcolor{blue}{component}, where we find that a displacement of \\textcolor{red}{$0.6$} pc nearly along the Galactic plane makes the two clouds fit well with each other. Based on these results we hypothesize that the two components collided with each other at a projected relative velocity $2.5$ km s$^{-1}$. The timescale of the collision is estimated to be $4 \\times10^5$ yrs for an assumed angle 45 deg of the relative motion to the line of sight. We assume that the two most massive early B--type stars in the cloud, illuminating stars of the two reflection nebulae, were formed by the collisional triggering at the \\textcolor{red}{interfaces} between the two clouds. Along with the other young high-mass star forming regions, M42, M43, and NGC2024 (Fukui et al. (2017) , Ohama et al. 2017 in prep), it seems possible that collisional triggering is independently working to form O--type and early B--type stars in Orion in the last Myr over a projected distance of $\\sim 80$ pc.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-06-18T14:38:52.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "high-mass star formation",
      "cloud-cloud collision",
      "orion possibly",
      "early b-type stars",
      "reflection nebulae"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}