  Optical and near-IR photometry suggests that the carbon star DY Persei
exhibits fadings similar to those of R Coronae Borealis (RCB) variables.
Photometric surveys of the Galaxy and Magellanic Clouds uncovered new DY Per
variables with infrared photometry identifying them with cool carbon stars,
perhaps, with an unusual tendency to shed mass. In an attempt to resolve DY
Per's identity crisis -- a cool carbon giant or a cool RCB variable? -- we
analyze a high-resolution H&K band spectrum of DY Per. The CO first-overtone
bands in the K-band of DY Per show a high abundance of 18O such that 16O/18O =
4 +- 1, a ratio sharply at odds with published results for `regular' cool
carbon giants with 16O/18O ~ 1000 but this exceptionally low ratio is
characteristic of RCB-variables and HdC stars. This similarity suggests that DY
Per indeed may be a cool RCB variable. Current opinion considers RCB-variables
to result from merger of a He onto a CO white dwarf; observed abundances of
these H-deficient stars including the exceptionally low 16O/18O ratios are in
fair accord with predicted compositions for white dwarf merger products. A
H-deficiency for DY Per is not directly observable but is suggested from the
strength of a HF line and an assumption that F may be overabundant, as observed
and predicted for RCB stars.
