# Detection of white dwarf spin period variability in the intermediate polar V2306 Cygni

## TL;DR

This study monitored the spin period of the white dwarf in the intermediate polar V2306 Cygni over nine years, detecting spin-up behavior and refining orbital period measurements to enhance understanding of magnetic accretion dynamics.

## Contribution

The paper presents the first detection of spin period variability in V2306 Cygni and provides precise measurements of its spin and orbital periods, contributing to the study of magnetic field interactions in such systems.

## Key findings

- Detected white dwarf spin-up with a characteristic time of (53±5)×10^4 years.
- Measured the spin period as 733.33976 seconds with high precision.
- Refined the orbital period to 4.371523±0.000009 hours.

## Abstract

Magnetic cataclysmic variables are close binaries which consist of a compact object - a white dwarf - and a red dwarf filling its Roche Lobe. Such systems are physical laboratories which enable study of the influence of magnetic fields on matter flows. They often exhibit spin-up or spin-down of the white dwarf, while some systems exhibit more complex behaviour of the spin period change. We monitor changes of the spin periods of white dwarfs in a sample of close binary systems to study interaction of the magnetic field and accretion processes as well as evolution of intermediate polars. Within the framework of our intermediate polar monitoring program, we obtained photometric CCD observations at several observatories. Two-period trigonometric polynomial fitting was used for determination of extrema timings. The (O-C) analysis was performed to study the variability of the orbital and spin periods of the systems. Using data taken during 9 years of observations of the magnetic cataclysmic variable V2306 Cygni (formerly known as 1WGA J1958.2+3232), we detected the spin period variability which shows a spin-up of the white dwarf with a characteristic time of $(53\pm5)\cdot10^4$ years. The value of the spin period was $733.33976$ seconds with the formal accuracy of $0.00015$ seconds. We derived an improved value of the orbital period of the system to be $4.371523\pm0.000009$ hours.