Spectroscopy of Seven Cataclysmic Variables with Periods above 5 Hours11Based on observations obtained at the MDM Observatory, operated by Dartmouth College, Columbia University, Ohio State University, and the University of Michigan.

Abstract

ABSTRACTWe present spectroscopy of seven cataclysmic variable stars with orbital periods Porb greater than 5 hr, all but one of which are known to be dwarf novae. Using radial velocity measurements we improve on previous orbital period determinations, or derive periods for the first time. The stars and their periods are TT Crt, 0.2683522(5) days; EZ Del, 0.2234(5) days; LL Lyr, 0.249069(4) days; UY Pup, 0.479269(7) days; RY Ser, 0.3009(4) days; CH UMa, 0.3431843(6) days; and SDSS J081321+452809, 0.2890(4) days. For each of the systems, we detect the spectrum of the secondary star, estimate its spectral type, and derive a distance based on the surface brightness and Roche lobe constraints. In five systems we also measure the radial velocity curve of the secondary star, estimate orbital inclinations, and, where possible, estimate distances based on the MV(max)‐ Porb relation found by Warner. In concordance with previous studies, we find that all the secondary stars have, to varying degrees, cooler spectral types than would be expected if they were on the main sequence at the measured orbital period.