Dust in the Universe

absorption abundance accretion Allamandola amorphous appears assumed Astron Astrophys atoms Bailey band calculations carbon Centre chemical circumstellar clouds comet cometary compared component composition containing curve density dependence detected diffuse discussed distribution effects emission et al evidence evolution example expected extinction feature field Figure formation galactic galaxies graphite Greenberg Halley hydrogen important indicates infrared intensity interstellar dust interstellar grains interstellar medium IRAS laboratory less light mantles mass material measured molecular clouds molecules Nature nebulae Netherlands nucleus objects observed occur optical organic origin PAHs particles phase physical polarization possible present produced properties radiation range ratio recent refractory region relative scattering shell shown shows silicate solar solid Space spectra spectrum stars stellar stellar wind structure suggests surface temperature ultraviolet University wavelength