The cataclysmic variable QZ Lib: a period bouncer

Understand

While highly evolved cataclysmic variables (CVs) with brown dwarf donors, often called "period bouncers", are predicted to make up $\simeq40-70$ % of the Galactic CV population, only a handful of such systems are currently known.

• The identification and characterization of additional period bouncers is therefore important to probe this poorly understood phase of CV evolution.
• We investigate the evolution of the CV QZ Lib following its 2004 super-outburst using multi-epoch spectroscopy.
• From time-resolved spectroscopic observations we measure the orbital period of the system, $P_\mathrm{orb}= 0.06436(20)$ d, which, combined with the superhump period $P_\mathrm{SH}= 0.064602(24)$ d, yields the system mass ratio, $q = 0.040(9)$.