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Abbott, Timothy M. C.; Robinson, Edward L.; Hill, Gary J. and Haswell, Carole A.
(1992).
DOI: https://doi.org/10.1086/171960
Abstract
We present time-series photometry of two faint, interacting binary stars at high Galactic latitude: CP Eridani and AL Comae Berenices. We also present spectroscopy of CP Eri. CP Eri has a long-lived photometric periodicity near 28 min. Its spectrum has lines of helium that are sometimes in emission and some times in absorption; there are no lines of hydrogen in the spectrum. We identify CP Eri as a binary star consisting of a pair of white dwarfs undergoing mass transfer. AL Com has an unstable, high-amplitude photometric modulation with a period between 87 and 90 min. The previously identified photometric period at 41 min is also unstable. Some of the properties of AL Com are similar to the dwarf nova WZ Sge and others are similar to the intermediate polar EX Hya, but overall AL Com is unlike any other well-studied cataclysmic variable.