Discovery and Characterization of an Extremely Deep-Eclipsing Cataclysmic Variable: LSQ172554.8-643839

TL;DR

This paper reports the discovery and detailed characterization of an extremely deep-eclipsing cataclysmic variable star, revealing its unique properties and suggesting it is a polar with a low-mass secondary star.

Contribution

The study presents the first detailed observation and analysis of LSQ172554.8-643839, a highly eclipsing cataclysmic variable with unprecedented eclipse depth and spectral features.

Findings

Eclipse depth > 5.7 mag and orbital period of 94.657 min.

Spectral type of secondary star is M8 or later.

Radial velocity oscillates with a semi-amplitude of 500 km/s.

Abstract

We report the discovery of an eclipsing cataclysmic variable with eclipse depths > 5.7 mag, orbital period 94.657 min, and peak brightness V~18 at J2000 position 17h 25m 54s.8, -64d 38' 39". Detected by visual inspection of images from Yale University's QUEST camera on the ESO 1.0-m Schmidt telescope at La Silla, we obtained light curves in B, V, R, I, z and J with the SMARTS 1.3-m and 1.0-m telescopes at Cerro Tololo and spectra from 3500 to 9000 Angstrom with the SOAR 4.3-m telescope at Cerro Pachon. The optical light curves show a deep, 5-min eclipse immediately followed by a shallow 38-min eclipse and then sinusoidal variation. No eclipses appear in J. During the deep eclipse we measure V-J > 7.1, corresponding to a spectral type M8 or later secondary, consistent with the dynamical constraints. The estimated distance is 150 psec. The spectra show strong Hydrogen emission lines, Doppler broadened by 600 - 1300 km/s, oscillating with radial velocity that peaks at mid deep eclipse with semi-amplitude 500 +/- 22 km/s. We suggest that LSQ172554.8-643839 is a polar with a low-mass secondary viewed at high inclination. No known radio or x-ray source coincides with the new object's location.