Request for Monitoring of QS Tel (1931-46)
Little is known about the optical behavior of the faint southern magnetic cataclysmic variable, QS Tel. That is why Dr. Christopher Mauche of the Lawrence Livermore National Laboratory has requested the assistance of AAVSO observers, particularly CCD observers, to help contribute to the fundamental understanding of this star's optical system by observing it at least until the end of 2004. Dr. Mauche informs us: "Regular observations are required to (1) establish the optical behavior of QS Tel, and (2) trigger an approved target-of-opportunity Chandra Low Energy Transmission Grating observation, which can take place only when the source is in a high state.
For more information, see Alert Notice 302.
Cataclysmic Variables (CVs) are binary systems consisting of a white dwarf and a red giant star with mass flowing from the red giant to the white dwarf via an accretion disk. Several Variable Star of the Season articles have been written on non-magnetic CVs including SS Cyg, U Gem, Z Cam, and RS Oph). QS Tel is a magnetic cataclysmic variable, however, where the accretion disk is disrupted by the white dwarf's magnetosphere. The accreting material leaves the disk and follows the magnetic field lines down to the white dwarf surface in the vicinity of the magnetic poles. As the accreting material rains down onto the white dwarf surface, it passes through a strong shock where its free-fall kinetic energy is converted into thermal energy. Magnetic cataclysmic variables, or "polars", are included in the AAVSO's High-Energy Network. There are many polars in the Network that have exciting and unpredictable variability that requires visual monitoring during periods of activity. For a review of magnetic cataclysmic systems, see also the AAVSO Variable Star of the Season articles on the "intermediate polar" GK Persei and the "polar" AM Herculis.
QS Tel is a very bright extreme ultraviolet and soft x-ray source likely to be of ongoing interest to researchers, so long-term optical coverage is very important. Because little is known about its optical behavior, this request for optical monitoring represents an opportunity for observers to add to the fundamental information on QS Tel.
Below is an image of QS Tel taken at 2003.09.26, 0215 UT by Bruce Gary who uses a 14-inch SCT with a SBIG ST-8XE CCD. With a clear filter, 8x60 sec, AO7-stabilized, elevation angle 12.1 degrees, FWHM seeing = 4.4 "arc, north up/east left, FOV = 6.0 x 5.1 'arc.