{
  "id": "0903.2623",
  "version": "v1",
  "published": "2009-03-15T10:38:48.000Z",
  "updated": "2009-03-15T10:38:48.000Z",
  "title": "Composite Grains: Effects of Porosity and Inclusions on the 10$μ$m Silicate Feature",
  "authors": [
    "Deepak B. Vaidya",
    "Ranjan Gupta"
  ],
  "comment": "14 pages, 6 figures -- to Appear in JQSRT (2009)",
  "doi": "10.1016/j.jqsrt.2009.03.011",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We calculate the absorption efficiency of the composite grains, made up of host silicate spheroids and inclusions of ices/graphites/or voids, in the spectral region $7.0-14.0\\mu$m The absorption efficiencies of the composite spheroidal grains for three axial ratios are computed using the discrete dipole approximation (DDA) as well as using the effective medium approximation & T-Matrix (EMT-Tmatrix) ap proach. We study the absorption as a function of the volume fraction of the inclusions and porosity. In particular, we study the variation in the $10.0\\mu$m feature with the volume fraction of the inclusions and porosity. We then calculate the infrared fluxes for these composite grains and compare the model curves with the average observed IRAS-LRS curve, obtained for several circumstellar dust shells around stars. These results on the composite grains show that the wavelength of the peak absorption shifts and the width of the $10.0\\mu$m feature varies with the variation in the volume fraction of the inclusions. The model curves for composite grains with axial ratios not very large (AR$\\sim$1.3) and volume fractions of inclusions with f=0.20, and dust temperature of about 250-300$^{\\circ}$K, fit the observed emission curves reasonably well.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2009-03-15T10:38:48.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "composite grains",
      "inclusions",
      "silicate feature",
      "volume fraction",
      "model curves"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "journal": "Journal of Quantitative Spectroscopy and Radiative Transfer",
      "year": 2009,
      "month": "Sep",
      "volume": 110,
      "pages": 1726
    },
    "note": {
      "typesetting": "TeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 815537,
      "adsabs": "2009JQSRT.110.1726V"
    }
  }
}