Interstellar Dust Models and Evolutionary Implications

Understand

The wavelength dependences of interstellar extinction and polarization, supplemented by observed elemental abundances and the spectrum of infrared emission from dust heated by starlight, strongly constrain dust models.

• One dust model that appears to be consistent with observations is presented.
• To reproduce the observed extinction, the model consumes the bulk of interstellar Mg, Si, and Fe (in amorphous silicates), and a substantial fraction of C (in carbonaceous material), with size distributions and alignment adjusted to match observations.
• The composition, structure, and size distribution of interstellar grains is the result of injection of dust from stellar outflows into the interstellar medium (ISM), followed by destruction, growth, coagulation, and photoprocessing of interstellar grains.