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Issue A&A Volume 375, Number 2, August IV 2001 Page(s) 584 - 590 Section Diffuse matter in space DOI 10.1051/0004-6361:20010867

A&A 375, 584-590 (2001)
DOI: 10.1051/0004-6361:20010867

Interstellar extinction by composite grains

D. B. Vaidya^{1, 2}, R. Gupta², J. S. Dobbie³ and P. Chylek<sup>3

1</sup>  Gujarat College, Ahmedabad 380009, India
    e-mail: vaidya@iucaa.ernet.in
²  IUCAA, Post Bag 4, Ganeshkhind, Pune 411007, India
³  Dept. of Physics, Dalhousie University, Halifax, Nova Scotia, B3H 3J5 Canada

(Received 11 December 2000 / Accepted 14 June 2001)

Abstract
Recent studies indicate that interstellar grains are composites of very small individual particles of silicates and carbon glued together into an aggregate. Using the discrete dipole approximation (DDA), we calculate the extinction, scattering and absorption efficiencies for composite grains assumed to be made of a host silicate sphere with embedded graphite inclusions. In particular, we study the extinction as a function of inclusion size and volume fraction. Using the extinction efficiencies of these composite grains, we evaluate the interstellar extinction curve in the wavelength region of .

Key words: ISM: dust -- extinction

Offprint request: R. Gupta, rag@iucaa.ernet.in

© ESO 2001

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