Composite Grains: Effects of Porosity and Inclusions on the 10$μ$m Silicate Feature
| dc.creator | Vaidya, Deepak B. | |
| dc.creator | Gupta, Ranjan | |
| dc.date | 2009-03-15 | |
| dc.date.accessioned | 2026-07-07T12:59:28Z | |
| dc.date.available | 2026-07-07T12:59:28Z | |
| dc.description | 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 $7.0-14.0μ$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 $10.0μ$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 $10.0μ$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}$K, fit the observed emission curves reasonably well. | |
| dc.description | 14 pages, 6 figures -- to Appear in JQSRT (2009) | |
| dc.identifier | https://arxiv.org/abs/0903.2623 | |
| dc.identifier | http://arxiv.org/abs/0903.2623 | |
| dc.identifier | doi:10.1016/j.jqsrt.2009.03.011 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/225581 | |
| dc.subject | Astrophysics of Galaxies | |
| dc.title | Composite Grains: Effects of Porosity and Inclusions on the 10$μ$m Silicate Feature | |
| dc.type | text |