The Eclipsing Cataclysmic Variable Lanning 386: Dwarf Nova, SW Sextantis Star, or Both?

TL;DR

This study confirms Lanning 386 as a cataclysmic variable with complex behavior, exhibiting characteristics of both dwarf novae and SW Sextantis stars, including deep eclipses, frequent outbursts, and high excitation features.

Contribution

It provides detailed photometric and spectroscopic analysis of Lanning 386, revealing its hybrid features and challenging existing classifications of CV subtypes.

Findings

Orbital period of 3.94 hours confirmed.

Frequent outbursts with up to 2 mag amplitude observed.

High state spectra show high excitation features like HeII and CIV.

Abstract

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 Porb to be 0.1640517 +- 0.0000001 d (= 3.94 h). Photometric monitoring over two observing seasons shows a very active system with frequent outbursts of variable amplitude, up to approx. 2 mag. The spectrum in quiescence is typical of dwarf novae, but in its high state the system shows strong HeII emission and a broad CIV 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.