Optical photometry of V4334 Sgr (Sakurai's Object)

Abstract

The optical photometric evolution of the final helium flash object V4334 Sgr from 1994 to 2000 is described. The rise to optical maximum (1994 - 1996) is characterized by a continuous increase of color indices, indicating a slowly expanding, cooling pseudo-photosphere. This photosphere became stationary in 1997. In the following years, the object underwent brightness declines of increasing strength, which are similar in character to the ``red declines'' of R CrB stars. The fading of V4334 Sgr is more dramatic than any brightness decline of an R CrB star: at present, only 1/100000 of the visual light reaches the observer. Most radiation is absorbed by the dust envelope and re-radiated in the infrared. The sparse optical data of 2000 show that the obscuration has not increased in strength any more. The light curve of V4334 Sgr is similar to that of the final helium flash object V605 Aql which erupted in 1919.