Magnetic Chemically Peculiar stars With Unsteady Periods

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Authors	MIKULÁŠEK Zdeněk KRTIČKA Jiří JANÍK Jan ZVĚŘINA Pavel ZVERKO Juraj ŽIŽNOVSKÝ Jozef ZEJDA Miloslav
Year of publication	2011
Type	Article in Proceedings
Conference	Magnetic Stars. Proceedings of the International Conference, held in the Special Astrophysical Observatory of the Russian AS
MU Faculty or unit	Faculty of Science
Citation
Field	Astronomy and astrophysics
Keywords	magnetic stars; CP stars; rotation
Description	Photometrically and spectroscopically variable chemically peculiar (CP) stars are the optimum laboratories for testing the rotational evolution of main sequence stars. A vast majority of well-studied CP stars have quite steady rotational periods (e. g. SrCrEu star CQ UMa). However, there are several CP stars that exhibit apparent period variations. The origin of the period variations is unclear in many cases. We describe the observed period variations of several individual CP stars, especially V901 Ori, sigma Ori E, HR 7355, CU Vir, SX Ari, and EE Dra. The CP stars with unsteady periods now represent a very diverse group with dissimilar O-C diagrams and time scales. We also discuss the causes of the period changes found and a possible cyclicity or chaoticity of them.
Related projects:	New approaches to variable stars data processing and interpretation Mass-loss rate predictions for hot stars