Intra-Night Flickering Of Rs Ophiuchi: Iv. Shapes Of Repeating Time Structures And Their Evolution

The flickering of the recurrent nova RS Oph is studied by 58 light curves (LCs), taken by 5 telescopes in 2008-2017. The light curves of the flickering source are derived after removal of the contribution of the red giant and account of the interstellar extinction. Many LCs show repeating time structures with approximately similar shapes. In this work we select 25 LCs (12 in B band and 13 in V band), with monitoring times 62-223 min, where the main time structures with quasi-periods 16-56 min repeat 3-7 times. We derive combined (averaged) profiles the structure and characterize them by shape parameters. The average SNR of the combined profiles is 26, from 10 to 43. In 2009-2017 the asymmetry (skewness ) of the shape varies gradually from positive to negative. Simultaneously, higher brightness and redder color indexes of the flickering source (in 2009-2010 or 2016-2017) correspond to positive or negative asymmetry of the combined profile.