Rotational periods of magnetic chemically peculiar stars

TL;DR

This paper reviews the rotational periods of magnetic chemically peculiar stars, highlighting their periodic variability, methods of measurement, and discrepancies with normal stars, including cases of period increases.

Contribution

It provides a comprehensive comparison of rotational periods of mCP stars with normal stars and discusses cases of period changes, enhancing understanding of stellar magnetic and rotational behavior.

Findings

Rotational periods of mCP stars can be measured with high accuracy.

Discrepancies exist between mCP stars and normal stars in rotational periods.

Some mCP stars show evidence of increasing rotational periods.

Abstract

Magnetic chemically peculiar (mCP) stars of the upper part of the main sequence usually exhibit strictly periodic variations of their light, spectrum and magnetic field. These changes can be well explained using the oblique rotator model of the rigidly rotating star with persistent photometric spots, uneven horizontal abundance of chemical elements and dipole-like magnetic field. Long-term observations of mCP stars variability enable to determine their rotational periods with an extraordinary accuracy and reliability. We compare rotational periods of mCP stars with those of normal main sequence stars of the same spectral type and discuss the found discrepancies. We also discuss the cases of mCP stars V901 Ori, SX Ari, CU Vir, (and possibly also EE Dra), which have been reported to display an increase of their rotational periods.