Formation of Dust Grains in Circumstellar Envelopes of Oxygen-Rich AGB Stars
Authors: Kozasa, Takashi; Sogawa, Hisato
Source: Astrophysics and Space Science, Volume 251, Numbers 1-2, July 1997 , pp. 165-170(6)
Abstract:We discuss dust formation in steady state dust driven winds around oxygen-rich AGB stars, including not only homogeneous Al2O3 and silicate grains but also heterogeneous grains consisting of an Al2O3 core and a silicate mantle. In the inner subsonic region, Al2O3 grains with radii of ∼ 0.15 µm condense first, then condensation of silicate on Al2O3 starts slightly inside the sonic point, which accelerates the gas flow into the supersonic region. Also small silicate grains, whose radii are a few tens of Ångstroms form beyond the sonic point. The carrier of 13 µm feature observed towards oxygen-rich AGB stars is considered to be the core-mantle grains consisting of an α-Al2O3 core and a silicate mantle from the radiation transfer calculations based on the results of dust formation calculations.
Document Type: Research Article
Publication date: July 1, 1997