{
  "id": "1108.2032",
  "version": "v1",
  "published": "2011-08-09T20:00:01.000Z",
  "updated": "2011-08-09T20:00:01.000Z",
  "title": "A Two-dimensional Map of Color Excess in NGC 3603",
  "authors": [
    "Xiaoying Pang",
    "Anna Pasquali",
    "Eva K. Grebel"
  ],
  "comment": "14 pages, 6 figures, 2 tables, accepted for publication in AJ",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Using archival HST/WFC3 images centered on the young HD 97950 star cluster in the giant HII region NGC 3603, we computed the pixel-to-pixel distribution of the color excess, E(B-V)g, of the gas associated with this cluster from its H_alpha/Pa_beta flux ratio. At the assumed distance of 6.9 kpc, the resulting median color excess within 1 pc from the cluster center is E(B-V)g =1.51 \\pm 0.04 mag. Outside the cluster (at r > 1 pc), the color excess is seen to increase with cluster-centric distance towards both North and South, reaching a value of about 2.2 mag at r = 2 pc from the cluster center. The radial dependence of E(B-V)g westward of the cluster appears rather flat at about 1.55 mag over the distance range 1.2 pc < r < 3 pc. In the eastern direction, E(B-V)g steadily increases from 1.5 mag at r = 1 pc to 1.7 mag at r = 2 pc, and stays nearly constant at 1.7 mag for 2 pc < r < 3 pc. The different radial profiles and the pixel-to-pixel variations of E(B-V)g clearly indicate the presence of significant differential reddening across the 4.9 pc \\times 4.3 pc area centered on the HD 97950 star cluster. We interpret the variations of E(B-V)g as the result of stellar radiation and stellar winds interacting with an inhomogeneous dusty local interstellar medium (ISM) whose density varies spatially. From the E(B-V)g values measured along the rims of the prominent pillars MM1 and MM2 in the southwest and southeast of the HD 97950 cluster we estimate an H2 column density of log10(N(H2))=21.7 and extrapolate it to log10(N(H2))=23 in the pillars' interior. We find the pillars to be closer to us than the central ionizing cluster and suggest that star formation may be occurring in the pillar heads.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2011-08-09T20:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "two-dimensional map",
      "star cluster",
      "inhomogeneous dusty local interstellar medium",
      "cluster center",
      "giant hii region ngc"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/0004-6256/142/4/132",
      "journal": "The Astronomical Journal",
      "year": 2011,
      "month": "Oct",
      "volume": 142,
      "number": 4,
      "pages": 132
    },
    "note": {
      "typesetting": "TeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 922839,
      "adsabs": "2011AJ....142..132P"
    }
  }
}