Joseph Patterson

ORBITAL PERIODS FOR SEVEN DWARF NOVAE OF THE SU URSAE MAJORIS SUBCLASS FROM RADIAL VELOCITIES AT MINIMUM LIGHT

We obtained time-resolved spectroscopy of seven SU UMa-type dwarf novae and determined orbital periods from velocities of their H-alpha emission lines. The stars and their periods are FO And (0.07161 d=103.1 min), FS Aur (0.0595 d=87.7 min), WX Cet (0.05826 d=82.9 min), AQ Eri (0.06093 d=87.7 min), TY Psc (0.06833 d=98.4 min), CY UMa (0.06957 d=100.2 min), and SS UMi (0.06778 d=97.6 min). This substantially increases the number of well-determined orbital periods Porb for SU UMa stars. The period uncertainties are all < 0.3 percent, sufficent to confront theories accounting for the superhumps observed photometrically during superoutbursts. Combining these periods with others from the literature we show that the correlation between superhump period excess delta-P/Porb and Porb is described by delta-P/Porb = -0.0344+(0.0382 hr-1) X Porb. The correlation is clear, but the scatter is greater than the measurement uncertainties. We also obtained contemporaneous timeseries photometry in the low state for TY Psc, AZ Eri, SS UMi, and CY UMa. TY Psc shows a ~0.2 mag modulation at the orbital period. While the others all show considerable variation, none of them appeared to vary periodically, and none eclipse. The white dwarf photosphere in TY Psc is noticable in the optical spectrum at minimum light.

1RXS J232953.9+062814: A Dwarf Nova with a 64 Minute Orbital Period and a Conspicuous Secondary Star*

We present spectroscopy and time series photometry of the newly discovered dwarf nova 1RXS J232953.9+062814. Photometry in the superoutburst reveals a superhump with a period of 66.06(6) minutes. The low-state spectrum shows Balmer and He I emission on a blue continuum and, in addition, a rich absorption spectrum of type K4 ± 2. The absorption velocity is modulated sinusoidally at Porb = 64.176(5) minutes, with semiamplitude of K = 348(4) km s-1. The low-state light curve is double humped at this period and is phased as expected for ellipsoidal variations. The absorption strength does not vary appreciably around the orbit. The orbital period is shorter than any other cataclysmic variable save for a handful of helium-star systems and V485 Centauri (59 minutes). The secondary is much hotter than main-sequence stars of similar mass, but it is well matched by helium-enriched models, indicating that the secondary evolved from a more massive progenitor. A preliminary calculation in which a 1.2 M☉ star begins mass transfer near the end of hydrogen burning matches this systems characteristics remarkably well.

High-speed photometry of SDSS J013701.06 − 091234.9

We present high-speed photometry of the Sloan Digital Sky Survey cataclysmic variable SDSS J013701.06 − 091234.9 in quiescence and during its 2003 December superoutburst. The orbital modulation at 79.71 ± 0.01 min is double-humped; the superhump period is 81.702 ± 0.007 min. Towards the end of the outburst late superhumps with a period of 81.29 ± 0.01 min were observed. We argue that this is a system of very low mass transfer rate, and that it probably has a long outburst interval.

Superhumps in Cataclysmic Binaries. XXV. Q~c~r~i~t' epsilon(q) and Mass-Radius

ABSTRACT We report on successes and failures in searching for positive superhumps in cataclysmic variables, and show the superhumping fraction as a function of orbital period. Basically, all short‐period system do, all long‐period systems do not, and a 50% success rate is found at \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

Pulsations, Boundary Layers, and Period Bounce in the Cataclysmic Variable RE J1255+266

P_{\mathrm{orb}\,}=3.1\pm 0.2

RAPID OSCILLATIONS IN CATACLYSMIC VARIABLES XVI. DW CANCRI

\end{document} hr. We can use this to measure the critical mass ratio for the creation of superhumps. With a mass‐radius relation appropriate for cataclysmic variables, and ...