[vsnet-rcb 644] UY Cen

[Taichi Kato]

UY Cen

   Dust-forming fading episode in a cool carbon star.  The fading of this
star was also mentioned and discussed in VSNET lists.  The paper also
illustrates the advantage of the ASAS data over traditional visual...

Paper: astro-ph/0506505
Date: Tue, 21 Jun 2005 19:07:13 GMT   (37kb)

Title: A Unique Dust Formation Episode in the SC-Type Star UY Cen
Authors: Justin D. R. Steinfadt, Geoffrey C. Clayton, Tom Lloyd Evans, and Tom
  Williams
Comments: 15 pages,, 3 figures, PASP in press (September 2005)
\\
  We report the first detection of new dust formation in an SC star. The
prototype of the SC stars, UY Cen, underwent a decline of 2 magnitudes in the
V-band. The SC stars show pulsational variations and have 60 micron excesses
indicating past dust formation. It has been suggested that as a star evolves
from oxygen rich to carbon rich, there is a short period of time when C/O$~1
that the star appears spectroscopically as an SC star and ceases to produce
dust. The SC star, BH Cru, has shown large spectroscopic and pulsation period
variations in only 30 years, indicating rapid evolution but it has shown no
sign of new dust formation. UY Cen has not shown any pulsation or spectroscopic
variations accompanying the onset of its dust formation. In addition, UY Cen
did not show emission in the resonance lines of Na I, K I or Rb I when it was
at its faintest, although these lines were a feature of the carbon stars R Lep
and V Hya during similar faint phases.
\\ ( http://arXiv.org/abs/astro-ph/0506505 ,  37kb)