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M.A. Stark, R.A. Wade (Penn State University), J.A. Orosz (Utrecht), G.B. Berriman (IPAC, Caltech)
We are continuing a study of hot subdwarf stars (sdB or sdO stars) that, on a statistical basis, appear to be members of wide binaries (common-proper-motion pairs). These c.p.m.\ candidates make up several percent of the approximately 1300 catalogued subdwarfs.
We present what is currently known about these pairs from literature and our own investigations, including: magnitude differences and colors, distribution of angular separation vs.\ magnitude, 2MASS colors, spectra, etc. Confirmation of these candidate binary systems awaits radial velocity and proper motion studies.
This sample cannot be regarded as complete in any rigorous way, and is certainly biased in the selection process. It nevertheless is showing promise that a purified sample can be used to learn about the luminosities, ages, and original metalicities of the hot subdwarf stars.