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Дата изменения: Thu Dec 23 17:46:30 2010 Дата индексирования: Thu Feb 27 21:03:28 2014 Кодировка: Поисковые слова: п п п р п р п р п |
Interstellar extinction and polarization: some theoretical results |
Tables give parameters of interstellar extinction and polarization
curves produced by rotating homogeneous spheroids with imperfect
Davis-Greenstein (IDG) orientation.
Das H.K., Voshchinnikov N.V., Il'in V.B. Interstellar extinction and polarization - A spheroidal dust grain approach perspective. Monthly Notices of Royal Astronomical Society, v.404, 265-274 (2010). (available here) Voshchinnikov N.V., Yakovlev I.S. The relationship between grain shape and interstellar polarization. In: Muinonen K. et al. (eds), Electromagnetic and Light Scattering: Theory and Applications, XII, pp. 318-321 (2010). (available here) Input parameters: ----------------- Material Type of spheroid (prolate/oblate) a/b - aspect ratio r_v,min - minimum size in power-law size distribution (r_v radius of a sphere whose volume is equal to that of spheroid) r_v,max - maximum size in power-law size distribution q0 - power degree idg - type of orientation 1/2=pdg/idg (imperfect/perfect Davis-Greenstein) del0 - degree of alignment Omega - angle between the line of sight and the magnetic field direction =============================================== Output parameters: ------------------ R_V - total-to-selective extinction ratio P/E(B-V) - polarizing efficiency of the interstellar medium (ratio of the maximum degree of linear polarization P_max to colour excess) IMPORTANT! Very large values of P/E(B-V) for a given model result from two facts: 1) colour excess E(B-V) is small (grey extinction) and/or 2) P(lam_max)>>P(V) and lam_max is far from the V band. lam_max - wavelength corresponding to P_max W - width of linear polarization curve ============================================== Materials: ------------------- asil_D03 - astronomical silicate (B.T. Draine, ApJ, 598, 1026, 2003). AC-Be - amorphous carbon (V.G. Zubko et al., MNRAS, 282, 1321, 1996). ============================================= |