The remarkable hot R Coronae Borealis star DY Cen is revealed to be the first and only binary system to be found among the R Coronae Borealis stars and their likely relatives , including the Extreme Helium stars and the hydrogen-deficient carbon stars .
Radial velocity determinations from 1982-2010 have shown DY Cen is a single-lined spectroscopic binary in an eccentric orbit with a period of 39.67 days .
It is also one of the hottest and most H-rich member of the class of RCB stars .
The system may have evolved from a common-envelope to its current form .