If there is a single word that one would use to describe the R Coronae Borealis (RCB) variable stars, it is enigmatic. This small, puzzling class of stars are most peculiar. With just under 50 known RCB stars, they appear to belong to an elite gang of rebellious variables. While we have been trained to think that activity of a star generally occurs as the star brightens, RCB stars prefer to do just the opposite. Choosing to spend the majority of their time at maximum brightness, this odd lot of variables are seen to be in an active phase as they fade to fainter magnitudes. In the seemingly backwards world of astronomy, where a smaller number implies a brighter stellar magnitude and a brighter star is generally indicative of activity, RCB variable stars seem to throw a wrench in the works of astronomical logic. It is an understatement then, to say that the RCB class of variable stars is unlike any other variable star grouping.

A closer look at the light curve of RY Sgr reveals evidence of a secondary Cepheid-like variation during maximum light of about 39 days and with an amplitude of about half a magnitude. This finding was first announced by Luigi Jacchia in 1933 on the basis of his observations during the time frame of 1920-1932. More recent studies by teams such as Marraco and Milesi (1982) and Lawson and Cottrell (1990) suggest that the pulsation period of RY Sgr may in fact be shortening. In their 1990 paper, Lawson and Cottrell concluded that perhaps the pulsation period is slowly changing on a time-scale of about every 10 years. Such a period change is postulated to be the result of rapid evolution of the post-giant phase of the helium-enriched star or may be due to a substantial mass loss. Both hypothesis, however, imply that the lives of the RCB stars as pulsators is very short -- perhaps on the order of a millennium (Marraco and Milesi 1982).