K2 study of the Magnetic Precataclysmic Variable V1082 Sagittarius

TL;DR

This study analyzes a long-term K2 light curve of V1082 Sgr, revealing its orbital period, cyclical variability, and stellar surface features, providing insights into its magnetic and accretion properties.

Contribution

First detailed analysis of V1082 Sgr's long-term light curve, detecting orbital and cyclical periods, and modeling the donor star's surface activity.

Findings

Detected the orbital period in the light curve.

Confirmed cyclical variability on a monthly timescale.

Modeled the donor star as a chromospherically active, under-filling star.

Abstract

We present a long-term light curve of the precataclysmic variable (CV) V1082 Sgr obtained by the K2-mission over the course of 81 days. We analyze the entire complex light curve as well as explore several sections in detail with a sliding periodogram. The long dataset allows the first detection of the orbital period in the light curve, as well as the confirmation of cyclical variability on a longer timescale of about a month. A portion of the light curve in deep minimum reveals a clean, near-sinusoidal variability attributed to the rotation of the spotted surface of the donor star. We model that portion of the light curve assuming that the donor star grossly under-fills its Roche lobe, has cool spots similar to a chromospherically active, slightly evolved early K-star, and might be irradiated by the X-ray beam from the magnetically accreting white dwarf. The fast variability of the object in the active phases resembles the light curves of magnetic CVs (polars).