Is "Spike" a Reliable Feature in Porb Distribution of AM HER Stars?

TL;DR

This study updates the orbital period distribution of AM Her stars, investigates the existence of a notable 'spike' feature near 114 minutes, and assesses its reliability as a characteristic of these magnetic cataclysmic variables.

Contribution

The paper provides an updated catalogue of polars and critically examines the previously reported 'spike' in their Porb distribution using new data.

Findings

The updated Porb distribution shows a possible concentration near 114 min.

The reliability of the 'spike' as a feature is questioned based on new data.

The study discusses implications for the evolution of magnetic cataclysmic variables.

Abstract

Orbital periods in AM Her stars (polars) are synchronized with spin periods of white dwarf by its high magnetic field. Since the last study of Porb distribution of these systems, the number of known objects of such type has more than doubled. This challenged us to compile a new updated catalogue of cataclysmic variables with highly magnetic white dwarfs (polars) and to study their Porb distribution. In this paper we also discus if "spike" is reliable feature in the distribution. ("Spike" is a concentration of polars in the distribution of their orbital periods near Porb = 114 min and was previously discussed by Ritter & Kolb (1992) and Shahbaz & Wood (1996).)