Post-superhumps maximum on intranight time scales of the AM CVn star CR Boo

TL;DR

This study observes intranight brightness variations and superhump behavior in the AM CVn star CR Boo, revealing post-superhump maxima shifts and their correlation with accretion processes, using multi-band photometry.

Contribution

First detailed intranight analysis of superhump maxima timing and amplitude shifts in CR Boo, linking post-superhump features to accretion dynamics.

Findings

Superhumps with amplitudes up to 0.25 mag observed.

Post-superhump maxima shifted by 7.62 to 16.35 minutes.

Correlation between post maxima and outer disc accretion processes.

Abstract

We present observations of the intranight brightness variability of CR Boo, a member of the AM CVn stars group. The observational data are obtained with the 2m telescope of the Rozhen National Astronomical Observatory and the 60 cm telescope of the Belogradchik Observatory, Bulgaria, in BVR bands. We report the appearance of superhumps, with an amplitude from 0.08 to 0.25 mag, when the maximum brightness reaches the magnitude 14.08 in the V band, and 14.13 in the B band. A secondary maximum of each superhump is detected with the same periodicity as the superhumps: Psh = 24.76 - 24.92 min. In our results, the post maxima are shifted in time from $\approx 7.62$ min to $\approx 16.35$ min in different nights, with an amplitude of $\approx 0.06 - 0.09$ mag and an amplitude difference of $\approx 0.035$ mag towards the superhumps' maximum. We find a correlation of the post maxima with the accretion processes at the outer side of the disc.