Dust in the Universe

absorption abundance accretion Allamandola amorphous assumed Astron Astrophys atoms Bailey band calculated Cambridge University Press carbon chemical circumstellar cloud comet Comet Halley cometary component composition containing cosmic ray curve density dependence diffuse discussed distribution dust particles effects emission et al evidence evolution example expected extinction feature field Figure formation galactic graphite Greenberg hydrogen important indicate infrared intensity interplanetary interstellar dust interstellar grains interstellar medium isotopic laboratory less Lett 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 shocks shown shows silicate solar solid Space spectra spectrum stars stellar stellar wind structure studies suggests surface temperature ultraviolet University wavelength