Mining R Coronae Borealis stars from Catalina surveys

Aims. R Coronae Borealis stars (RCBs) are rare carbon stars that lack of hydrogen in their photospheresand are most likely products of white dwarf mergers. A census of RCBs can shed light on the progenitors of SNe Ia in the context of a double degenerate scenario. Methods. Traditionally, RCBs are identified by their unpredictable photometric variation with dimmings up to 9 mag, and thus discoveries of RCBs are heavily biased to the limited regions monitored by long-term microlensing experiments. However, recent studies of galactic RCBs have shown that they exhibit distinct mid-infrared colors originating from their cool circumstellar shells, and the all-sky WISE survey facilitates the identification of RCB candidates. Therefore, combining the WISE colors with large area time-domain surveys will enable us to discover more RCBs. Results. This study presents the results of 26 RCB candidates from the Catalina surveys, where five of them are spectroscopically confirmed RCBs and seven of them are previously known carbon stars. This demonstrates the efficacy of this kind of an approach and the potential to discover uncharted RCBs in ongoing and future synoptic surveys