Possible indicator of incipient light minimum in a star with the R Coronae Borealis type variability

The appearance of the 25 km s(-1) blue-shifted component in the Na I D lines may be interpreted as an indicator of the beginning of a visual light minimum in stars with the R Coronae Borealis type variability. Since 1994, this component was a forerunner of the visual light minimum in R CrB itself at least three times. In the 1995, 1998, and probably in the 2003 minimum, it was found for a day or several days before the beginning of light decline. A similar relation was also found for the infrared triplet line Ca II lambda 854.2 nm.