Determining the magnitudes and spectral types of the components of the binary Mira X Ophiuchi

Abstract

Several values for the magnitudes and spectral types of the components of the binary Mira X Ophiuchi have been published in the literature over the last century. Analysis of new photometry and spectroscopy of the star between 2016 May and 2016 December indicates that the V magnitude of the constant star is 9.0 and its spectral type K1III. The spectral type of the Mira changed from M6III at maximum to M7III as it faded and passed through minimum. The V magnitude of the Mira varied between 6.47 at maximum and 9.83 at minimum, a range of 3.36 magnitudes.