The Superoutburst Duration versus Orbital Period Relation for AM CVn Stars

Abstract

We examine the relationship between superoutburst duration t dur and orbital period P orb in AM CVn ultra-compact binary systems. We show that the previously determined steep relation derived by Levitan et al. was strongly influenced by the inclusion of upper limits for systems with a relatively long orbital period in their fit. Excluding the upper limit values and including t dur values for three systems at long P orb that were not considered previously, then is flat as predicted by Cannizzo & Nelemans.