The SW Sex phenomenon as an evolutionary stage of Cataclysmic Variables

TL;DR

The paper proposes that the SW Sex phenomenon is an evolutionary phase in the life cycle of cataclysmic variables, occurring during their orbital period evolution driven by angular momentum loss.

Contribution

It introduces the idea that SW Sex stars represent a transitional evolutionary stage in cataclysmic variables based on recent observational data.

Findings

Nearly all non-magnetic CVs with 2.8-4 hr periods are SW Sex type.

SW Sex phase occurs before systems enter the period gap.

High mass transfer rates characterize SW Sex systems.

Abstract

From recent large observing campaigns, one finds that nearly all non- or weakly magnetic cataclysmic variables in the orbital period range between 2.8 and 4 hours are of SW Sex type and as such experience very high mass transfer rates. The evolution of cataclysmic variables as for any interacting binary is driven by angular momentum loss which results in a decrease of the orbital period on evolutionary time scales. In particular, all long-period systems need to cross the SW Sex regime of the orbital period distribution before entering the period gap. This makes the SW Sex phenomenon an evolutionary stage in the life of a cataclysmic variable. Here, I present a short overview of the current state of research on these systems.