Hot spot in eclipsing dwarf nova IY Ursae Majoris during quiescence and normal outburst

TL;DR

This study analyzes the hot spot brightness in the eclipsing dwarf nova IY UMa during quiescence and outburst, revealing significant changes only during outburst and supporting the disk-instability model.

Contribution

It provides direct observational evidence of hot spot brightness variation correlating with outburst activity in IY UMa, confirming the disk-instability model.

Findings

Hot spot brightness varies significantly during outburst.

Hot spot brightness remains stable before and after outburst.

Results support the disk-instability model for dwarf novae.

Abstract

We present the analysis of hot spot brightness in light curves of the eclipsing dwarf nova IY Ursae Majoris during its normal outburst in March 2013 and in quiescence in April 2012 and in October 2015. Examination of four reconstructed light curves of the hot spot eclipses showed directly that the brightness of the hot spot changed significantly only during the outburst. The brightness of the hot spot, before and after the outburst, was on the same level. Hereby, based on the behaviour of the hot spot, IY UMa during its normal outburst follows the disk-instability model.