Radial velocity studies of HeII and HβHβ emission from cataclysmic variables

•Modeling radial velocity (RV) curves helps explain contributing factors.•Factors include eccentricity, inclination angle, disk-tilt, and bright spots.•Fitting outlying data points can lead to a more accurate portrait of the system.•Gas stream overflow can also influence radial velocity curves.•We model and inspect RV curves of CV SW Sextanis and SU UMa dwarf novae systems.

Radial velocity (RV) plots of HeII and HβHβ emission lines from non-magnetic Cataclysmic Variable (CV) systems are frequently fit with a sin curve but sometimes contain outlying data points around phase ϕ∼1.0ϕ∼1.0. A lack of consensus exists on the origin of these outlying points. In this work, we develop an analytical model that is based upon our 3D Smoothed Particle Hydrodynamic (SPH) numerical model to simulate these RV curves. Our chosen targets are CV SW Sextanis-like systems UX Uma and RW Tri as well as SU UMa dwarf novae systems H  αα0242–28 and 1RXSJ1808+10, which have secondary-to-primary mass ratios of q = (0.43, 0.86, 0.27, 0.18), respectively. In our model, we include disk eccentricity, inclination angle, degree of disk-tilt, bright spot (s  ), and/or gas stream overflow. Our model provides good non-sinusoidal fits to the observed RV data, including outlying data points near ϕ∼1.0ϕ∼1.0, suggesting these excess points may be caused by gas-stream overflow.