Dust formation and wind acceleration around the aluminum oxide-rich AGB star W Hydrae.
basic_science · Level V
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- Record sourced from PubMed, PMID 29109978.
- Also identified by DOI 10.1126/sciadv.aao2149 and PMC identifier 5665597.
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Abstract
Dust grains, formed around asymptotic giant branch (AGB) stars, are accelerated by stellar radiation to drive stellar winds, which supply freshly synthesized nuclides to the Galaxy. Silicate is the dominant dust species in space, but ~40% of oxygen-rich AGB stars are thought to have comparable amounts of aluminum oxide dust. Dust formation and the wind-driving mechanism around these oxygen-rich stars, however, are poorly understood. We report on the spatial distributions of AlO and <sup>29</sup>SiO molecules around an aluminum oxide-rich M-type AGB star, W Hydrae, based on observations obtained with the Atacama Large Millimeter/submillimeter Array. AlO molecules were only observed within three stellar radii (<i>R</i><sub>star</sub>), whereas <sup>29</sup>SiO was distributed in the accelerated wind beyond 5 <i>R</i><sub>star</sub> without significant depletion. This strongly suggests that condensed aluminum oxide dust plays a key role in accelerating the stellar wind and in preventing the efficient formation of silicate dust around W Hydrae.