Superhump and outburst activity of the cataclysmic variable RZ LMi in the U $U$ - and optical passbands

Abstract

An analysis of the new $U,B,V,R_{C},I_{C}$ -photometry of the cataclysmic variable RZ LMi obtained in 2016–17 showed the largest $(U-B)$ colour excess in quiescence as well as during the decline of brightness, associated with the outbursts activity. The smallest $(U-B)$ colour excess was found during the brightness increase from the quiescence. In contrast to the $(U-B)$ colour index, the $(B-V),(V-R_{C}),(R_{C}-I_{C})$ colour indices exhibits the largest colour excesses near the maximum of the outburst and the smallest during the quiescence. The $(B-V)$ colour index showed also a large excess 1–2 days before a minimum. The detailed study of superhumps during the maximum of activity reveals the largest $(U-B)$ colour excess at the time of the minimum brightness of superhumps. The $(B-R_{C})$ colour index exhibits a similar behaviour, but with a phase shift of $+0.1\mbox{--}{+}0.2$ period of superhumps. The tracks in two-colour and colour-magnitude diagrams during superoutbursts are compared with the data for other cataclysmic variables during their outbursts as well as with published theoretical calculations.