Research ArticleASTRONOMY

Dust formation and wind acceleration around the aluminum oxide–rich AGB star W Hydrae

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Science Advances  01 Nov 2017:
Vol. 3, no. 11, eaao2149
DOI: 10.1126/sciadv.aao2149
  • Fig. 1 AlO N = 9–8 transition observed around W Hya.

    (A) AlO (N = 9–8) line spectrum. Error bars represent the SD obtained in the sky region. The positions of the 12 hyperfine structures of the N = 9–8 transition (19) at the local standard-of-rest velocity of 40.4 km s−1 (20) are also indicated (vertical blue lines). (B) Continuum-subtracted and integrated AlO intensity map. The open ellipse in the bottom left-hand corner represents the synthesized beam size. The dashed circles show locations at 3 and 5 Rstar from the star. (C) Comparison of the AlO distribution (contours of brightness in units of Jy beam−1 km s−1) and a polarized intensity map at 645 nm reflecting the dust distribution (13).

  • Fig. 2 29SiO line (v = 0, J = 8–7) observed around W Hya.

    (A) Integrated intensity map of 29SiO. The open ellipse in the bottom left-hand corner represents the synthesized beam size. The dashed circles show locations at 3, 5, and 10 Rstar from the star. (B) Annular-averaged line profile of 29SiO at 39.5, 40.4, and 41.2 km s−1. The modeled brightness of 29SiO in the preaccelerated region at 0.07 arc sec (3 Rstar) is shown by a circle, and the modeled abundance profiles with different degrees of 29SiO depletion (10, 30, 50, 70, and 90%) owing to silicate formation are shown for comparison (see Materials and Methods).

  • Fig. 3 Position-velocity diagrams of 29SiO line (v = 0, J = 8–7) around W Hya.

    (A) R.A. plane. (B) Dec. plane. White rectangles represent the spatial and velocity resolution.

  • Fig. 4 Dust formation and wind acceleration around W Hya.

    Aluminum oxide dust, which grows and piles up in the inner dust shell, and partially condensed silicate dust trigger the acceleration of the wind, which suppresses silicate formation around an aluminum oxide–rich star like W Hya.

Supplementary Materials

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Channel map of the 29SiO for different velocities.
    • fig. S2. Radial distribution of modeled 29SiO emission.

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