We obtained time-series radial velocity spectroscopy of twenty cataclysmic variable stars , with the aim of determining orbital periods P _ { orb } .
All of the stars reported here prove to have P _ { orb } > 3.5 h. For sixteen of the stars , these are the first available period determinations , and for the remaining four ( V709 Cas , AF Cam , V1062 Tau , and RX J2133+51 ) we use new observations to improve the accuracy of previously-published periods .
Most of the targets are dwarf novae , without notable idiosyncracies .
Of the remainder , three ( V709 Cas , V1062 Tau , and RX J2133+51 ) are intermediate polars ( DQ Her stars ) ; one ( IPHAS 0345 ) is a secondary-dominated system without known outbursts , similar to LY UMa ; one ( V1059 Sgr ) is an old nova ; and two others ( V478 Her and V1082 Sgr ) are long-period novalike variables .
The stars with new periods are IPHAS 0345 ( 0.314 d ) ; V344 Ori ( 0.234 d ) ; VZ Sex ( 0.149 d ) ; NSVS 1057+09 ( 0.376 d ) ; V478 Her ( 0.629 d ) ; V1059 Sgr ( 0.286 d ) ; V1082 Sgr ( 0.868 d ) ; FO Aql ( 0.217 d ) ; V587 Lyr ( 0.275 d ) ; V792 Cyg ( 0.297 d ) ; V795 Cyg ( 0.181 d ) ; V811 Cyg ( 0.157 d ) ; V542 Cyg ( 0.182 d ) ; PQ Aql ( 0.247 d ) ; V516 Cyg ( 0.171 d ) ; and VZ Aqr ( 0.161 d ) .
Noteworthy results on individual stars are as follows .
We see no indication of the underlying white dwarf star in V709 Cas , as has been previously claimed ; based on the non-detection of the secondary star , we argue that the system is farther away that had been thought and the white dwarf contribution is probably negligible .
V478 Her had been classified as an SU UMa-type dwarf nova , but this is incompatible with the long orbital period we find .
We report the first secondary-star velocity curve for V1062 Tau .
In V542 Cyg , we find a late-type contribution that remains stationary in radial velocity , yet the system is unresolved in a direct image , suggesting that it is a hierarchical triple system .