GALEX and Optical Light Curves of WX LMi, SDSSJ103100.5+202832.2 and SDSSJ121209.31+013627.7

{\it GALEX} near ultraviolet (NUV) and far-ultraviolet (FUV) light curves of three extremely low accretion rate polars show distinct modulations in their UV light curves. While these three systems have a range of magnetic fields from 13 to 70 MG, and of late type secondaries (including a likely brown dwarf in SDSSJ121209.31+013627.7), the accretion rates are similar, and the UV observations imply some mechanism is operating to create enhanced emission zones on the white dwarf. The UV variations match in phase to the two magnetic poles viewed in the optical in WX LMi and to the single poles evident in the optical in SDSSJ1212109.31+013627.7 and SDSSJ103100.55+202832.2. Simple spot models of the UV light curves show that if hot spots are responsible for the UV variations, the temperatures are on the order of 10,000-14,000K. For the single pole systems, the size of the FUV spot must be smaller than the NUV and in all cases, the geometry is likely more complicated than a simple circular spot.Comment: 29 pages, 4 tables, 10 figures, Astrophysical Journal, accepte

On the orbital period of the cataclysmic variable RZ Leonis

In this research note we present a time-resolved study of the Balmer emission lines of RZ Leo. From the analysis of the radial velocities we find an orbital period of 0.07651(26) d. This is in excellent agreement with the photometrically determined periods in quiescence and during the early stages of superoutburst. A comparison of the recently determined superhump period gives an excess of ~0.03, which is a typical value for an SU UMa star of this period.Comment: 3 pages, 6 figures, A&A, accepte

Keck IR Spectroscopy of WZ Sge: Detection of Molecular Emission from the Accretion Disk

Time-resolved IR spectroscopy of WZ Sge was obtained using NIRSPEC on Keck II. We detect CO and H$_{\rm 2}$ emission from the accretion disk placing WZ Sge into a rarefied class of astronomical objects including YSOs and high luminosity early-type stars. During the eclipse phase, the molecular emission greatly weakens but no firm evidence for the secondary star is seen allowing new limits on its luminosity to be determined. The detection of molecular emission provides physical properties within the outer disk of T=3000K and N$_H$$>10^{10}$ cm$^{-3}$. Such a cool, dense region, not associated with areas of H I and He I emission, provides the first observational confirmation of predictions made by accretion disk models.Comment: 10 pages, 3 figures. Accepted for publication in ApJ Letter

V3885 Sagittarius: a Comparison with a Range of Standard Model Accretion Disks

A $\widetilde{\chi}^2$ analysis of standard model accretion disk synthetic spectrum fits to combined $FUSE$ and STIS spectra of V3885 Sagittarius, on an absolute flux basis, selects a model that accurately represents the observed SED. Calculation of the synthetic spectrum requires the following system parameters. The cataclysmic variable secondary star period-mass relation calibrated by Knigge in 2007 sets the secondary component mass. A mean white dwarf (WD) mass from the same study, that is consistent with an observationally-determined mass ratio, sets the adopted WD mass of $0.7M_{\odot}$, and the WD radius follows from standard theoretical models. The adopted inclination, i=65{\arcdeg}, is a literature consensus, and is subsequently supported by $\widetilde{\chi}^2$ analysis. The mass transfer rate is the remaining parameter to set the accretion disk $T_{\rm eff}$ profile, and the $Hipparcos$ parallax constrains that parameter to $\dot{M}=5.0{\pm}2.0{\times}10^{-9} M_{\odot} {\rm yr}^{-1}$ by a comparison with observed spectra. The fit to the observed spectra adopts the contribution of a $57,000{\pm}5000$K WD. The model thus provides realistic constraints on $\dot{M}$ and $T_{\rm eff}$ for a large $\dot{M}$ system above the period gap.Comment: 41 pages, 7 figures, 9 tables. Astrophysical Journal (accepted