AAS 203rd Meeting, January 2004
Session 83 Stars Variable in Light
Poster, Wednesday, January 7, 2004, 9:20am-6:30pm, Grand Hall

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[83.06] Dust Formation in the SC-type Star UY Cen

J.D.R. Steinfadt (U. of Arizona and Maria Mitchell Obs.), G.C. Clayton (Louisiana State U. and Maria Mitchell Obs.)

In February of 2002, the unassuming, small amplitude variable star UY Cen was observed by AAVSO astronomer Colin Henshaw in Oman to have vanished from the sky. Upon further observation, Henshaw and other AAVSO observers found the star had faded by more than two magnitudes. A historical study using prior published and unpublished observations, including those of archival photographic plates, and an analytical study of UY Cen was carried out during the summer of 2003. The primary results are presented here. Prior publications have classified UY Cen in the range of M-, C-, S-, and SC- type with little agreement. Closer analysis of recent spectroscopic data pinpointed the unique absorption features (ZrO, TiO, Na D) to be those of an SC-type star. Being that there are less than thirty confirmed or suspected SC-type stars, this classification raises more questions than it answers. Has UY Cen gone into decline before? Can we expect this sort of behavior from other SC-type stars, or if not, what makes UY Cen special compared with other stars of this class? Upon analysis of over one hundred photographic plates dating back to 1890 in the Harvard College Observatory plate archive, we can conclude that UY Cen has gone into decline at least once in the last century. Analysis of infrared data taken prior to and during the decline suggests dust formation. However, photometric data taken before the decline fitted with a black body curve shows no infrared excess prior to decline. Comparison of UY Cen to other SC-type stars showed no distinguishing characteristics other than the decline of 2002. This first analysis only partly answered our questions; there still remain many more questions to be answered of this unusual star. This project was supported by the NSF/REU grant AS T-0097694 and the Nantucket Maria Mitchell Association.

The author(s) of this abstract have provided an email address for comments about the abstract: justins@physics.arizona.edu

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.