Binary stars are a very important source of astronomical information. Those short-period binaries observed by means of both spectroscopy and interferometry can provide, through their corresponding orbits, precise values regarding individual masses as well as orbital parallaxes. For this reason, it is fundamental to attempt to optically resolve double-lined spectroscopic binaries. In the present article, we used the elaboration of a specific algorithm in order to determine the necessary telescope aperture to resolve a concrete spectroscopic binary. To that end, using available photometric and spectroscopic information, we established a 3D model for each spectroscopic binary with an orbit from which we deduced the most probable maximum and minimum separations between the components. In this manner, using the obtained calibrations in our study, we also deduced different physical parameters of the components of each system. The methodology presented here was tested satisfactorily with a list of spectroscopic binaries that had been optically resolved and that have both the spectroscopic and visual orbits.

The study of a selected set of 69 double-lined spectroscopic binaries (SB2) with well-defined visual and spectroscopic orbits was carried out. The orbital parallax, the mass, the colour, and the luminosity of each component were derived from observational data for almost all of these systems. We have also obtained an independent estimation of the component masses by comparing the colour–magnitude diagram (CMD) to the stellar evolution tracks reported by Pietrinferni. Nearly all of the observational points on the CMD are located between two tracks of slightly different mass or which fall very close to the one corresponding to a unique mass value. The masses obtained from the stellar model are in good agreement with their empirical values determined by parallax techniques (orbital, Gaia, and dynamical). This means that our adopted model is rather reliable and can therefore be used to infer further information, such as the age of each component in the studied systems. Our results indicate a fair correspondence between the age of primaries and secondary stars within 3σ. Nevertheless, we caution that these age indications suffer of uncertainties due to both inhomogeneities/low precision of the adopted photometric data and possible systematics. Finally, it is statistically shown that along with the orbital and trigonometric parallaxes, the dynamical parallax can serve as a reliable tool for distance estimates.

A complete astrophysical and dynamical study of the close visual binary system (CVBS) (A7V + F0V), Finsen 350, is presented. Beginning with the entire observational spectral energy distribution (SED) and the magnitude difference between the subcomponents, Al-Wardat's complex method for analyzing close visual binary stars (CVBS) was applied as a reverse method of building the individual and entire synthetic SEDs of the system. This was combined with Docobo's analytic method to calculate the new orbits. Although possible short (≈ 9 years) and long period (≈ 18 years) orbits could be considered taking into account the similar results of the stellar masses obtained for each of them (3.07 and 3.41 M ⊙ , respectively), we confirmed that the short solution is correct. In addition, other physical, geometrical and dynamical parameters of this system such as the effective temperatures, surface gravity accelerations, absolute magnitudes, radii, the dynamical parallax, etc., are reported. The main sequence phase of both components with age around 0.79 Gy is approved.

The precise determination of the physical and dynamical parameters of the HIP 109951 triple star system (WDS J22161-0705AB) which is formed by the A, Ba, and Bb components are presented. The binary nature of component B was recently confirmed by studying the radial velocities. The analysis of the system follows Al-Wardat's complex method for analyzing CVBS which employs Kurucz (Atlas9) line blanketed plane-parallel atmospheres simultaneously with an analytic method for dynamical analysis (we used Docobo's method) to calculate the parameters of this triple system. The result of our study yielded the following parameters: T A eff = 5836 ± 80 K, R A = 1.090 ± 0.039R , logg A = 4.45 ± 0.06, M A = 1.05 ± 0.16M ; T Ba eff = 5115 ± 80 K, R Ba = 0.596 ± 0.05R , log g Ba = 4.60 ± 0.07, M Ba = 0.83 ± 0.16M , T Bb eff = 4500 ± 80 K, R Bb = 0.490 ± 0.06R , log g Bb = 4.65 ± 0.07, and M Bb = 0.67 ± 0.16M based on the revised Hipparcos parallax. The orbital solution gave a total mass as M = 2.59M based on Gaia parallax and M = 2.15M based on the revised Hipparcos parallax. The synthetic spectral energy distributions (SED) and synthetic stellar photometry of the entire system and individual components are given and compared with the available observational ones. Finally, the positions of the system components on the HR diagram and the evolutionary tracks are given and their formation and the evolution of the system are discussed.

By combining our improved visual orbit with the last spectroscopic solution of the single-lined spectroscopic binary, MCA 74 (ADS 16672Aa, Ab; HD 219834A), we derived its orbital solution to have a period of 6.321 years. Using the Gaia parallax, a systemic mass of 1.87 ± 0.09 and a mass ratio of q = 0.725 were obtained, which yielded individual masses of 1.07 ± 0.06 and 0.80 ± 0.04 for the main and the secondary components, respectively. The mass and the absolute magnitude of +3.52 confirm that the primary is a late G5–G8 subgiant, while the same parameters of the secondary (Mv = +6.52) suggest that it is an early K2–K3 dwarf.