USNO-A2.0 1575-02008711 , the SIMBAD biblio

We report the discovery of five new dwarf novae that were spectroscopically identified in the Hamburg Quasar Survey (HQS), and discuss the properties of the sample of new dwarf novae from the HQS.Follow-up time-resolved spectroscopy and photometry have been obtained to characterise the new systems.The orbital periods determined from analyses of the radial velocity variations and/or orbital photometric variability are P_orb≃105.1min or P_orb≃109.9min for HS0417+7445, P_orb=114.3±2.7min for HS1016+3412, P_orb=92.66±0.17min for HS1340+1524, P_orb=272.317±0.001min for HS1857+7127, and P_orb=258.02±0.56min for HS2214+2845. HS1857+7127 is found to be partially eclipsing. In HS2214+2845 the secondary star of spectral type M3±1 is clearly detected, and we estimate the distance to the system to be d=390±40pc. We recorded one superoutburst of HS0417+7445, identifying the system as a SU UMa-type dwarf nova. HS1016+3412 and HS1340+1524 have rare outbursts, and their subtype is yet undetermined. HS1857+7127 frequently varies in brightness and may be a ZCam-type dwarf nova. HS2214+2845 is a UGem-type dwarf nova with a most likely cycle length of 71d. To date, 14 new dwarf novae have been identified in the HQS. The ratio of short-period (<3h) to long-period (>3h) systems of this sample is 1.3, much smaller compared to the ratio of 2.7 found for all known dwarf novae. The HQS dwarf novae display typically infrequent or low-amplitude outburst activity, underlining the strength of spectroscopic selection in identifying new CVs independently of their variability. The spectroscopic properties of short-period CVs in the HQS, newly identified and previously known, suggest that most, or possibly all of them are still evolving towards the minimum period. Their total number agrees with the predictions of population models within an order of magnitude. However, the bulk of all CVs is predicted to have evolved past the minimum period, and those systems remain unidentified. This suggests that those post-bounce systems have markedly weaker Hβ emission lines compared to the average known short-period CVs, and undergo no or extremely rare outbursts.