Luminosity class of the symbiotic stars 4U1954+319 and ZZ CMi

Abstract

We performed optical photometry and spectral observations of the symbiotic stars 4U1954+319 and ZZ CMi. For 4U1954+319, using high-resolution spectra, we, measure the equivalent widths of diffuse interstellar bands (DIBs) and estimate the interstellar reddening E(B-V) = 0.83 ? 0.09. Using the GAIA distances and our photometry, we find: (1) the absolute V-band magnitude MV = -5.23 ? 0.08 of 4U1954+319 and that the mass donor is a supergiant of luminosity class Ib, and (2) MV = -0.27 ? 0.2 for ZZ CMi and that the mass donor is a giant of luminosity class III.