Secondary stars in cataclysmic variables ( CVs ) follow a well defined period-density relation .
Thus , canonical donor stars in CVs are generally low-mass stars of spectral type M. However , several CVs have been observed containing secondary stars which are too hot for their inferred masses .
This particular configuration can be explained if the donor stars in these systems underwent significant nuclear evolution before they reached contact .
In this paper we present SDSS J001153.08-064739.2 as an additional example belonging to this peculiar type of CV and discuss in detail its evolutionary history .
We perform spectroscopic and photometric observations and make use of available Catalina Real-Time Transient Survey photometry to measure the orbital period of SDSS J001153.08-064739.2 as 2.4 hours and estimate the white dwarf ( \mbox { $M _ { \mathrm { wd } } $ } > 0.65 \mbox { $ \mathrm { M } _ { \odot } $ } ) and donor star ( 0.21 \mbox { $ \mathrm { M } _ { \odot } $ } < M _ { \mathrm { don } } < 0.45 \mbox { $ \mathrm { M } _ { \odot } $ } ) masses , the mass ratio ( q = 0.32 \pm 0.08 ) , the orbital inclination ( 47 ^ { \circ } < i < 70 ^ { \circ } ) , derive an accurate orbital ephemeris ( T _ { 0 } = 2453383.578 ( 1 ) + \mathrm { E } \times 0.10028081 ( 8 ) ) , and report the detection of an outburst .
We show that SDSS J001153.08-064739.2 is one of the most extreme cases in which the donor star is clearly too hot for its mass .
SDSS J001153.08-064739.2 is therefore not only a peculiar CV containing an evolved donor star but also an accreting CV within the period gap .
Intriguingly , approximately half of the total currently-observed sample of these peculiar CVs are located in the period gap with nearly the same orbital period .