{
  "id": "2406.05978",
  "version": "v1",
  "published": "2024-06-10T02:34:39.000Z",
  "updated": "2024-06-10T02:34:39.000Z",
  "title": "Deep Search for Phosphine in a Prestellar Core",
  "authors": [
    "Kenji Furuya",
    "Takashi Shimonishi"
  ],
  "comment": "10 pages, 4 figures, 1 Table, accepted for publication in ApJL",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Understanding in which chemical forms phosphorus exists in star- and planet-forming regions and how phosphorus is delivered to planets are of great interest from the viewpoint of the origin of life on Earth. Phosphine (PH3) is thought to be a key species to understanding phosphorus chemistry, but never has been detected in star- and planet-forming regions. We performed sensitive observations of the ortho-PH3 $1_0-0_0$ transition (266.944 GHz) toward the low-mass prestellar core L1544 with the ACA stand-alone mode of ALMA. The line was not detected down to 3$\\sigma$ levels in 0.07 km s$^{-1}$ channels of 18 mK. The non-detection provides the upper limit to the gas-phase PH3 abundance of $5\\times10^{-12}$ with respect to H2 in the central part of the core. Based on the gas-ice astrochemical modeling, we find the scaling relationship between the gas-phase PH3 abundance and the volatile (gas and ice with larger volatility than water) P elemental abundance for given physical conditions. This characteristic and well-constrained physical properties of L1544 allow us to constrain the upper limit to the volatile P elemental abundance of $5\\times10^{-9}$, which is a factor of 60 lower than the overall P abundance in the ISM. Then the majority of P should exist in refractory forms. The volatile P elemental abundance of L1544 is smaller than that in the coma of comet 67P/C-G, implying that the conversion of refractory phosphorus to volatile phosphorus could have occurred along the trail from the presolar core to the protosolar disk through e.g., sputtering by accretion/outflow shocks.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-06-10T02:34:39.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "deep search",
      "elemental abundance",
      "gas-phase ph3 abundance",
      "low-mass prestellar core l1544",
      "upper limit"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}