UGPS J194310+183851: an Unusual Optical and X-ray Faint Cataclysmic Variable?

TL;DR

This paper reports the discovery of a potentially new type of magnetic cataclysmic variable star with unusual optical, infrared, and X-ray properties, likely belonging to the short-period Intermediate-Polar subclass.

Contribution

It identifies and characterizes a novel magnetic cataclysmic variable with atypical spectral energy distribution and possibly longer spin period, expanding understanding of such systems.

Findings

Likely a short-period Intermediate-Polar system

System's SED is fainter and redder than typical members

Possible longer spin period than average for similar systems

Abstract

The growing number of multi-epoch optical and infrared sky surveys are uncovering unprecedented numbers of new variable stars, of an increasing number of types. The short interval between observations in adjacent near infrared filters in the UKIDSS Galactic Plane Survey (UGPS) allows for the discovery of variability on the timescale of minutes. We report on the nature of one such object, through the use of optical spectroscopy, time-series photometry and targeted X-ray observations. We propose that UGPS J194310.32+183851.8 is a magnetic cataclysmic variable star of novel character, probably featuring a longer than average spin period and an orbital period likely to be shorter than the period gap (i.e. P$_{\text{orb}}$<2 hours). We reason that the star is likely a member of the short period Intermediate-Polar subclass that exist below this period boundary, but with the additional feature that system's SED is fainter and redder than other members of the group.