{
  "id": "1604.03188",
  "version": "v1",
  "published": "2016-04-12T00:55:47.000Z",
  "updated": "2016-04-12T00:55:47.000Z",
  "title": "Line-of-sight velocity and metallicity measurements of the Palomar 5 tidal stream",
  "authors": [
    "Miho N. Ishigaki",
    "Narae Hwang",
    "Masashi Chiba",
    "Wako Aoki"
  ],
  "comment": "14 pages, 13 figures. Accepted for publication in ApJ",
  "categories": [
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "We present Subaru/FOCAS and Keck/DEIMOS medium-resolution spectroscopy of a tidally disrupting Milky Way (MW) globular cluster Palomar 5 and its tidal stream. The observed fields are located to cover an angular extent of $\\sim 17$\\arcdeg along the stream, providing an opportunity to investigate a trend in line-of-sight velocities ($V_{\\rm los}$) along the stream, which is essential to constrain its orbit and underlying gravitational potential of the Milky Way's dark matter halo. A spectral fitting technique is applied to the observed spectra to obtain stellar parameters and metallicities ([Fe/H]) of the target stars. The 19 stars most likely belonging to the central Pal 5 cluster have a mean $V_{\\rm los}$ of $-58.1\\pm 0.7$ km s$^{-1}$ and metallicity [Fe/H]$=-1.35\\pm 0.06$ dex, both of which are in good agreement with those derived in previous high-resolution spectroscopic studies. Assuming that the stream stars have the same [Fe/H] as the progenitor cluster, the derived [Fe/H] and $V_{\\rm los}$ values are used to estimate the possible $V_{\\rm los}$ range of the member stars at each location along the stream. Because of the heavy contamination of the field MW stars, estimated $V_{\\rm los}$ range depends on prior assumptions about the stream's $V_{\\rm los}$, which highlights the importance of more definitely identifying the member stars using proper motion and chemical abundances to obtain an unbiased information of $V_{\\rm los}$ in the outer part of the Pal 5 stream. The models for the gravitational potential of the MW's dark matter halo that are compatible with the estimated $V_{\\rm los}$ range are discussed.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-04-12T00:55:47.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "tidal stream",
      "line-of-sight velocity",
      "metallicity measurements",
      "mws dark matter halo",
      "member stars"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2016arXiv160403188I"
    }
  }
}