[93.12] The Velocity Structure of the Circumstellar Nebula of the Extreme Red Supergiant VY CMa

AAS 203rd Meeting, January 2004
Session 93 Stars, Their Facts and Legends
Poster, Wednesday, January 7, 2004, 9:20am-6:30pm, Hanover Hall

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[93.12] The Velocity Structure of the Circumstellar Nebula of the Extreme Red Supergiant VY CMa

G. Ruch, R. M. Humphreys (Univ. Minn.), G. H. Herbig (Univ. Hawaii)

VY CMa is one of the most luminous red supergiants and most powerful OH/IR masers known. HST/WFPC2 images showed the asymmetric nebula with embedded structures including bright clumps of knots and three large arcs at different orientations that are evidence for multiple asymmetric mass loss events.

We have obtained long slit spectra with HIRES on the Keck1 telescope at different positions on the nebula. The spectra reveal the presence of multiple velocity systems. The strong absorption lines show a velocity gradient across the nebula while the very strong K I emission line has a very complex profile with dramatic variations as the slit crosses knots and filaments. We will discuss these results in the context of separate mass loss events in the recent history of this remarkable star.

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