Precursor outbursts and superoutbursts in the SU UMa-type dwarf nova NN Camelopardalis

TL;DR

This study analyzes multiple outbursts of the SU UMa-type dwarf nova NN Cam, revealing details about precursor events, superhump behavior, and orbital period, contributing to understanding of dwarf nova outburst mechanisms.

Contribution

First detailed photometric analysis of NN Cam's outbursts, confirming orbital period and measuring superhump period changes, advancing knowledge of SU UMa-type dwarf novae behavior.

Findings

Detected superhumps during superoutbursts with decreasing period.

Confirmed the orbital period as 0.0717 days.

Estimated binary mass ratio between 0.11 and 0.17.

Abstract

We report photometry of three outbursts of NN Cam in 2007, 2008 and 2009. The 2007 event started with a normal outburst, lasting about 4 days, which was a precursor to a superoutburst lasting at least 13 days. Both the precursor and the superoutburst had an amplitude of 4.9 mag above mean quiescence. Superhumps with a maximum peak-to-peak amplitude of 0.22 mag were detected during the superoutburst with a mean superhump period Psh = 0.07385(56) d. Psh decreased continuously with dPsh /dt = -1.72(23) x 10-3. We used our measurement to confirm that the shorter of two possible values of Porb reported by another researcher is the correct one, Porb = 0.0717 d. The 2008 outburst was rather poorly observed, although we present evidence that this too may have been a superoutburst. The 2009 event was also a superoutburst, with Psh = 0.07414(44) d, but we could find no evidence for a precursor. From the 2007 and 2009 data, we report a superhump period excess of epsilon = 0.030(8) to 0.034(6), which is typical for SU UMa dwarf novae of similar orbital period, and estimate the binary mass ratio q = Mwd/Msec $\simeq$ 0.11 to 0.17