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Paper: On the Orbital Period Distribution of Cataclysmic Variables from Hamburg Quasar Survey
Volume: 404, The Eighth Pacific Rim Conference on Stellar Astrophysics: A Tribute to Kam Ching Leung
Page: 276
Authors: Aungwerojwit, A.; Gänsicke, B.T.
Abstract: We present the period distribution of 44 new cataclysmic variables (CVs) from the Hamburg Quasar Survey (HQS). The CV candidates were selected from the presence of Balmer emission lines. It is clear that our survey did not identify the large number of new short-period CVs predicted by the population models. The ratio of short-period (≤ 3 h) to long-period (> 3 h) systems of the new HQS sample is only half that of the previously known CVs. The HQS CV survey has been very prolific in identifying bright long-period CVs, with a distinct preference for the 3.4 h period range, of which nearly half are SW Sex stars which hold one-fourth of all HQS CVs above the period gap. Judging from the total number of short-period CVs in the HQS sample, their space density falls short by at least a factor of 2.3 compared to the values predicted by population models, suggesting that the bulk of short-period CVs predicted by the standard evolution scenario does either not exist, or has markedly weaker Hβ emission lines compared to the average known short-period CVs.
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