We present simultaneous g′, Rc, and Ic photometry of the notable dwarf nova ER UMa during the 2011 season. Our photometry revealed that the brightness maxima of negative superhumps coincide with the bluest peaks in g′−Ic colour variations. We also found that the amplitudes of negative superhumps are the largest in the g′ band. These observed properties are significantly different from those observed in early and positive superhumps. Our findings are consistent with a tilted disk model as the light source of negative superhumps.
@article{arxiv.1805.02452,
title = {On the Colour Variations of Negative Superhumps},
author = {Akira Imada and Kenshi Yanagisawa and Nobuyuki Kawai},
journal= {arXiv preprint arXiv:1805.02452},
year = {2018}
}