Cataclysmic variables from the Calán-Tololo Survey - II. Spectroscopic periods

Abstract

In this second paper on cataclysmic variables detected in the Calan–Tololo Survey we present time-resolved spectroscopy for the remaining eight systems without a measured orbital period. We derive orbital periods for all of these systems, where we find two objects with periods above the period gap and six systems with periods shorter than 2 h. We discuss the spectroscopic results and do not find any specific general reason why the period could not be determined from photometry. This does imply that to study the period distribution of a large sample of cataclysmic variables phase-resolved spectroscopy is required. We also looked at the general results for the cataclysmic variables in the Calan–Tololo Survey (CTS). Our main objective was to search for the (very) short-period cataclysmic variables that population-synthesis models indicate are missing from the observed sample. However, we find that the sample of cataclysmic variables detected in the CTS is not fundamentally different from the known sample and does not provide an explanation for the discrepancy between population-synthesis models and the observed sample.