HS 0922 + 1333 : another low accretion rate polar with a pronounced cyclotron line spectrum ?

We present time resolved spectroscopy of the newly discovered magnetic CV HS 0922+1333. Our observations show that it has a period of 244±2 min. Its optical spectra are dominated by a strong single spot cyclotron line at 5334Å. A detailed analysis shows that further cyclotron harmonics are at 7800Å (hidden by the M dwarf companion) and at 4034Å which yields a field strength of 66 MG (n = 2, 3 and 4). A much weaker spot appears to be present at antiphase with B 81 MG (n = 2 and 3 visible). HS 0922+1333 does not show any emission lines (like Balmer, HeII) except the cyclotron harmonics. It has an extremely low accretion rate of the order of 3 · 10 −13 M yr −1 , atypical for its long period. It has not been detected by ROSAT. HS 0922+1333 is the third member of a class of strong cylotron line emitters (low accretion rates) defined by HS 1023+3900 and 1RXS J012851.9−233933, both probably in the CV period gap, while HS 0922+1333 is clearly above the period gap. At a distance of 190 pc the WD primary is rather faint (M B = 12.6) and cool (T eff ≤ 10 000 K) implying the system is old.