Discovery of the 2010 Eruption and the Pre-Eruption Light Curve for Recurrent Nova U Scorpii

TL;DR

This paper reports the 2010 eruption of recurrent nova U Scorpii, analyzes pre-eruption light curves, and predicts the timing of the next eruption based on historical data and flux analysis.

Contribution

It provides the first detailed pre-eruption light curve analysis for U Sco and refines eruption timing predictions using flux and mass accretion data.

Findings

No significant long-term brightness variations before eruption.

Eruption peak occurred at JD 2455224.69 ± 0.07.

Next eruption predicted around 2020 ± 2 years.

Abstract

We report the discovery by B. G. Harris and S. Dvorak on JD 2455224.9385 (2010 Jan 28.4385 UT) of the predicted eruption of the recurrent nova U Scorpii (U Sco). We also report on 815 magnitudes (and 16 useful limits) on the pre-eruption light curve in the UBVRI and Sloan r' and i' bands from 2000.4 up to 9 hours before the peak of the January 2010 eruption. We found no significant long-term variations, though we did find frequent fast variations (flickering) with amplitudes up to 0.4 mag. We show that U Sco did not have any rises or dips with amplitude greater than 0.2 mag on timescales from one day to one year before the eruption. We find that the peak of this eruption occurred at JD 2455224.69+-0.07 and the start of the rise was at JD 2455224.32+-0.12. From our analysis of the average B-band flux between eruptions, we find that the total mass accreted between eruptions is consistent with being a constant, in agreement with a strong prediction of nova trigger theory. The date of the next eruption can be anticipated with an accuracy of +-5 months by following the average B-band magnitudes for the next ~10 years, although at this time we can only predict that the next eruption will be in the year 2020+-2.