A Catalog of GALEX Ultraviolet Emission from Asymptotic Giant Branch
  Stars
  We have performed a comprehensive study of the UV emission detected from AGB
stars by the Galaxy Evolution Explorer (GALEX). Of the 468 AGB stars in our
sample, 316 were observed by GALEX. In the NUV bandpass ($\lambda_{\rm eff}
\sim 2310$z A), 179 AGB stars were detected and 137 were not detected. Only 38
AGB stars were detected in the FUV bandpass ($\lambda_{\rm eff} \sim1528$ A).
We find that NUV emission is correlated with optical to near infrared emission
leading to higher detection fractions among the brightest, hence closest, AGB
stars. Comparing the AGB time-variable visible phased light curves to
corresponding GALEX NUV phased light curves we find evidence that for some AGB
stars the NUV emission varies in phase with the visible light curves. We also
find evidence that the NUV emission, and possibly, the FUV emission are
anti-correlated with the circumstellar envelope density. These results suggest
that the origin of the GALEX-detected UV emission is an inherent characteristic
of the AGB stars that can most likely be traced to a combination of
photospheric and chromospheric emission. In most cases, UV detections of AGB
stars are not likely to be indicative of the presence of binary companions.
