Colours of the flickering source of Mira

Abstract

We report photometric observations in Johnson UBV bands of the short term variability of Mira. The amplitude detected is 0.16 mag in B band. Adopting interstellar extinction E(B-V)=0, we find for the flickering source colour B-V=1.3, temperature T=3700 K, and radius R=0.77 Rsun. The colour of the flickering source is considerably redder than the average B-V colour of the cataclysmic variables.