Spectroscopy of V341 Arae: A Nearby Nova-like Variable inside a Bow-Shock Nebula

TL;DR

This study confirms V341 Arae as a nearby nova-like cataclysmic variable with a bow-shock nebula, providing spectroscopic evidence of its orbital period and similarities to other known systems, and discusses its possible interaction with the interstellar medium.

Contribution

The paper provides the first spectroscopic confirmation of V341 Arae as a nova-like CV and details its orbital period, nebula association, and potential past nova outburst.

Findings

V341 Arae is a nova-like CV with a 0.15216-day orbital period.

The star is associated with a bow-shock nebula, similar to BZ Cam.

V341 Arae is one of the nearest bright nova-like variables at 156 pc.

Abstract

V341 Arae is a 10th-magnitude variable star in the southern hemisphere, discovered over a century ago by Henrietta Leavitt but relatively little studied since then. Although historically considered to be a Cepheid, it is actually blue and coincides with an X-ray source. The star lies near the edge of the large, faint Halpha nebula Fr 2-11, discovered by D. Frew, who showed that V341 Ara is actually a cataclysmic variable (CV). His deep imaging of the nebula revealed a bow-shock morphology in the immediate vicinity of the star. We have carried out spectroscopic monitoring of V341 Ara, and we confirm that it is a nova-like CV, with an orbital period of 0.15216 days (3.652 hr). We show that V341 Ara is remarkably similar to the previously known BZ Cam, a nova-like CV with a nearly identical orbital period, associated with the bow-shock nebula EGB 4. Archival sky-survey photometry shows that V341 Ara normally varies between V ~ 10.5 and 11, with a characteristic timescale ranging from about 10 to 16 days. V341 Ara lies well off-center within Fr 2-11. We speculate either that the star is undergoing a chance high-speed encounter with a small interstellar cloud, or that the nebula was ejected from the star itself in a nova outburst in the fairly distant past. At a distance of only 156 pc, V341 Ara is one of the nearest and brightest known nova-like variables, and we encourage further studies.