Аннотация
This work (on Microfiche MN 195/1) is the third part of an investigation aimed at studying pairs of galaxies containing Markarian galaxies. It concerns a spectrographs study of 66 pairs made in order to get the radial velocities of the normal components so that physical pairs can be separated from optical ones. The spectra were obtained with a three-stage magnetic focusing image-tube at the Cassegrain |$f/16$| focus of the Alma-Ata 70-cm telescope. Morphological data are also given for four systems from electronographs obtained at the Newton |$f/5$| focus of the Haute-Provence 193-cm telescope (fields of Markarian 87, 95, 141 and 159). The physical parameters are given in Table 3: distances, radial velocity differences, absolute magnitudes and linear separations. Also given are ‘circular’ masses, i.e. masses obtained for each of two equal-mass isolated galaxies, in circular motion, for an edge-on orbit. (ℳc). We also give the mean ‘circular’ mass-to-light ratios (|$\mu_\text c$|); the purpose is simply to point out possible peculiarities deserving further study. Kinematical times (τ) are listed; for stable systems they are of the order of the periods, for unstable ones they would give evaluations of their ages. Last we give the probability (p) for each normal galaxy to form a physical pair with the corresponding Markarian galaxy; p is a function of the angular separation easily obtained from our previous work and given in Fig. 3. One-half of the normal galaxies in our pairs show emission lines. Most of the linear separations between normal and Markarian galaxies range from 10 to 130 kpc. with a median value 67 kpc. These values are small compared with the average separation between galaxies belonging to a group or between field galaxies, hence the name ‘close pairs’ used in this work. The distributions of relative velocities |$|\Delta V|$| and of the probabilities p of being physical pairs are given in Fig. 5. Fifty-seven per cent of the pairs have |$|\Delta V|\lt 200\enspace\text {km s}^{-1}$| and a mass-to-light ratio |$\mu_\text c\lt 30$|; their mean p is 63 per cent, thus 14 of these 23 pairs should be stable systems. Four pairs have |$|\Delta V|\gt 500\enspace\text {km s}^{-1}$| and |$\mu_\text c\gt 30$|; they might be optical pairs according to a classical view, however, their mean p is quite high (83 per cent). Further study of these systems could be interesting. There are 12 pairs having |$|\Delta V|$| in the range 200–500 km s−1 and eight of them have |$\mu_\text c\gt 30$|; their mean p is 64 per cent. Their status is not clear. The distributions of the mass-to-light ratios |$\mu_\text c$| and of the kinematic times τ are given in Fig. 6. Their median values are 8.5 and 4 × 108yr respectively. Pairs with large |$\mu_\text c$|, large p and small τ should, with unconventional views, correspond to galaxies of recent origin. They are located in the lower right corner of Fig. 6.