Discovery of Five New R Coronae Borealis Stars in the MACHO Galactic Bulge Database

We have identified five new R Coronae Borealis (RCB) stars in the Galacticbulge using the MACHO Project photometry database, raising the total number ofknown Galactic RCB stars to about 40. We have obtained spectra to confirm theidentifications. The fact that four out of the five newly identified RCB starsare ``cool'' (T(eff) < 6000 K) rather than ``warm'' (T(eff) > 6000 K) suggeststhat the preponderance of warm RCB stars among the existing sample is aselection bias. These cool RCB stars are redder and fainter than their warmcounterparts and may have been missed in surveys done with blue plates. Basedon the number of new RCB stars discovered in the MACHO bulge fields, there maybe ~250 RCB stars in the reddened "exclusion" zone toward the bulge.