The eclipsing cataclysmic variable lanning 386: Dwarf nova, SW sextantis star, or both?

摘要

We present photometry and spectroscopy of the suspected cataclysmic variable (CV) Lanning 386. We confirm that it is a CV, and observe deep eclipses, from which we determine the orbital period P-orb to be 0.1640517 +/- 0.0000001 days (= 3: 94 h). Photometric monitoring over two observing seasons shows a very active system with frequent outbursts of variable amplitude, up to similar to 2 mag. The spectrum in quiescence is typical of dwarf novae, but in its high state the system shows strong He II emission and a broad C IV Wolf-Rayet feature. This is unusual for dwarf novae in outburst and indicates a high excitation. In its high state the system shows some features reminiscent of an SW Sextantis-type CV, but lacks others. We discuss the classification of this puzzling object.