Recent humps and superhumps observations and an estimation of outburst parameters of the AM CVn star CR Boo

TL;DR

This study reports multi-band observations of the AM CVn star CR Boo, documenting its brightness variations, the appearance of humps and superhumps, and estimating outburst parameters and color-temperature changes.

Contribution

It provides new observational data on CR Boo's superhumps, humps, and color variations, with estimated periodicities and outburst parameters based on multi-night observations.

Findings

Superhumps detected with periods ~24.76-24.92 min.

Brightness varies between 13.95 and 17.23 in B band.

CR Boo becomes bluer during superhumps and outbursts.

Abstract

We present our observational results of AM CVn star CR Boo in the UBVR bands. Our observational campaign includes data obtained over 5 nights with the National Astronomical Observatory Rozhen, Belogradchik and the AS Vidojevica telescopes. During the whole time of our observations the brightness of the system varied between $13.95 - 17.23$ in B band. We report the appearance of humps during the period of quiescence and superhumps during the active state of the object, (where the latter are detected in two nights). We obtain the superhumps periodicity for two nights, $P_{sh}\approx 24.76 - 24.92$ min. The color during maximum brightness is estimated as $ - 0.107 < (B-V)_{0} < 0.257$ and the corresponding temperature is in the range as $7700 [K] < T(B-V)_{0} < 11700 [K]$. We found that CR Boo varies from bluer to redder in the nights with outbursts activity. The star becomes bluer during the times of superhumps.