# The Superoutburst Duration versus Orbital Period Relation for AM CVn stars

## TL;DR

This study revises the relationship between superoutburst duration and orbital period in AM CVn stars, showing it is flatter than previously thought when considering new data and excluding certain upper limits.

## Contribution

It demonstrates that the superoutburst duration versus orbital period relation is flatter than earlier reports suggested, aligning with theoretical predictions.

## Key findings

- The relation is flatter when excluding upper limits.
- Including new long-period systems alters the relation.
- Supports theoretical models predicting a flat relation.

## Abstract

We examine the relationship between superoutburst duration $t_{\rm dur}$ and orbital period $P_{\rm orb}$ in AM CVn ultra-compact binary systems. We show that the previously determined steep relation derived by Levitan et al (2015) 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 $t_{\rm dur}$ values for three systems at long $P_{\rm orb}$ which were not considered previously, then $d \log (t_{\rm dur})/ d \log (P_{\rm orb})$ is flat as predicted by Cannizzo & Nelemans(2015)