Indicator of a forthcoming light minimum in a star with R Coronae Borealis type variability

This is an examination of the hypothesis that the appearance of a component with a negative displacement of about −25 km/s in the lines of the sodium resonance doublet can serve as an indicator of the near-term onset of a visual light minimum of a star with R Coronae Borealis type variability. This effect has been observed three times since 1994 in connection with a brightness minimum: twice for a day or a few days before the beginning of a drop in brightness (1995, 1998) and, perhaps, once during the first days of a minimum (2003). Similar changes have been noted in one of the lines of the infrared CaII triplet at 854.2 nm. __________ Translated from Astrofizika, Vol. 50, No. 4, pp. 603–620 (November 2007).