Multifrequency study of the very slow nova V723 Cas

Abstract

Multifrequency behaviour of the very slow nova V723 Cas is reviewed. The long-term photometry of the object revealed the orbital period 0.693265 days of the binary, quasi-periodic oscillations in the envelope of the burst white dwarf and 182 days periodicity of activity due to the mass transfer bursts from the red to the white dwarf probably caused by a periastron passage of the third body. The photometry at the maximum of brightness was used to calculate the velocity v = 210 km s^-1 of ejection of an expanding supergiant photosphere --- main inner envelope of the nova. The emission line profiles in nebular stage show multiple peaks formed in an expanding equatorial ring and polar blobs of this envelope. The He I line profile and radio observations suggest the existence of the outer envelope, shaped and accelerated by the spherical and polar winds, detected as absorption components of the H I and He I P Cygni type line profiles. Radio observations allowed to determine ejected mass 2.5×10^-4 M_⊙ and confirmed the clumpy structure of the ejecta.