The magnetic variability of the $\beta$~Cep star $\xi^{1}$\,CMa

TL;DR

This study investigates the magnetic variability of the star ξ¹ CMa, comparing recent spectropolarimetric data with past measurements, and finds no evidence supporting a long rotation period as previously suggested.

Contribution

The paper provides new spectropolarimetric measurements that challenge previous claims of an extremely long rotation period for ξ¹ CMa.

Findings

New measurements show magnetic field strength between 115 and 240 G.

Results do not support the existence of a rotation period longer than 30 years.

Comparison indicates consistency with a shorter rotation period.

Abstract

$\xi^{1}$ CMa is a known magnetic star showing rotationally modulated magnetic variability with a period of 2.17937 d. However, recent work based on high-resolution spectropolarimetry suggests that the rotation period is longer than 30 years. We compare our new spectropolarimetric measurements with FORS 2 at the VLT acquired on three consecutive nights in 2017 to previous FORS 1/2 measurements of the longitudinal magnetic field strength. The new longitudinal magnetic field values are in the range from 115 to 240 G and do not support the presence of a long period.