AAS 199th meeting, Washington, DC, January 2002
Session 92. Circumstellar Material and Atmospheres: Cooler
Display, Wednesday, January 9, 2002, 9:20am-6:30pm, Exhibit Hall

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[92.17] The Cool Hypergiants: Imaging their Circumstellar Environments

M.T. Schuster, R.M. Humphreys (University of Minnesota)

The cool hypergiants are evolved massive stars that lie just below the empirical upper luminosity boundary in the HR Diagram, with spectral types ranging from late A to M. Recent observations of two of these stars (IRC +10420 and VY CMa) have yielded surprising results about their circumstellar environments including evidence for bi-polarity, equatorial disks, and multiple high mass loss events. To better understand their mass loss histories, we obtained high resolution WF/PC2 PC images of 7 of the most luminous known cool stars to sample a variety of stages during their brief evolution as cool hypergiants. the presence or lack of fossil shells, equatorial ejecta, jets and other structures in their circumstellar environments is a record of their current and prior mass loss episodes. NML Cyg, Rho Cas, Mu Cep, VX Sgr, S Per, HR 8752, and HR 5171A were selected on the basis of their infrared emission, strong molecular emission, or peculiar spectroscopic variations to give us a snapshot of different steps in their evolution across the top of the HR Diagram. We have also imaged these same stars in the near and mid-infrared. We present evidence for extensive circumstellar material and discuss the implications for their evolutionary state.

The author(s) of this abstract have provided an email address for comments about the abstract: hercu@astro.umn.edu

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