We present the complete set of atmospheric and fundamental parameters, in addition to the masses, for the individual components of eight stellar systems. The list of the systems, whose orbital solutions were published recently, includes seven binaries (HIP 14524, HIP 16025, HIP 46199, HIP 47791, HIP 60444, HIP 61100, HIP 73085) and one triple system (HIP 28671). The systems were analyzed using a spectrophotometric computational technique known as Al-Wardats method for analyzing binary and multiple stellar systems, which makes use of ATLAS9 line-blanketed plane-parallel model atmospheres. Using these estimated parameters, the positions of the components were located on the Hertzsprung–Russell diagram, evolutionary tracks and isochrones to estimate their ages, the range depending on the uncertainties in their metallicities. Five systems were found to be pre-main-sequence stars (HIP 14524, HIP 46199, HIP 60444, HIP 61100, HIP 73085), two were main-sequence stars (the zero-age HIP 28671 and the 6.3 Gyr HIP 16025), and one is a subgiant system (HIP 47791) with an age of 1.4 Gyr. Fragmentation is proposed as the most probable formation process for the eight systems. A comparison between the estimated masses and the dynamical ones lead to new dynamical parallaxes for four systems: (28.63 ± 0.56) mas for HIP 14524, (15.6 ± 0.63) mas for HIP 16025, (9.73 ± 0.26) mas for HIP 47791, and (16.53 ± 0.59) mas for HIP 73085. Hence, the orbital solutions were reclassified. We conclude that Gaia DR3 parallaxes are more precise than those given by Gaia DR2 and Hipparcos 2.

Data release 2 (DR2) from the Gaia mission was of great help in precise determination of fundamental parameters of Close Visual Binary and Multiple Systems (CVBMSs), especially masses of their components, which are crucial parameters in understanding formation and evolution of stars and galaxies. This article presents the complete set of fundamental parameters for two nearby close visual binary systems (CVBSs), which are HIP 19206 and HIP 84425. We utilised a combination of two methods; the first one is Tokovinin’s dynamical method to solve the orbit of the system and to estimate orbital elements and the dynamical mass sum, and the second one is Al-Wardat’s method for analysing CVBMSs to estimate the physical parameters of the individual components. The latest method employs grids of Kurucz line-blanketed plane parallel model atmospheres to build synthetic Spectral Energy Distributions (SEDs) of the individual components. Trigonometric parallax measurements given by Gaia DR2 and Hipparcos catalogues are used to analyse the two systems. The difference in these measurements yielded slight discrepancies in the fundamental parameters of the individual components, especially masses. So, a new dynamical parallax is suggested in this work based on the most convenient mass sum as given by each of the two methods. The new dynamical parallax for the system HIP 19205 of 22.97 ± 0.95 mas coincides well with the trigonometric one reported recently (in December 2020) by Gaia EDR3 of 22.3689 ± 0.4056 mas. The positions of the components of the two systems on the evolutionary tracks and isochrones are plotted, which suggest that all components are solar-type main sequence stars. Their most probable formation and evolution scenarios are also discussed.

We present a solution for the problem of the discrepancy in the measured trigonometric parallaxes for the stellar binary system HIP 84092. To solve the discrepancy, we used the orbital parameters and our method for analyzing binary and multiple stellar systems (BMSSs)s, described by Al-Wardat in 2002. We used all the available parallax measurements from Gaia DR3, DR2 and Hipparcos-2 in estimating the fundamental parameters of the individual components of the system. Such measurements are usually affected by the orbital motion of the components and the shift of the system photocenter. The masses estimated using the Al-Wardat method along with the modified orbital elements lead to a new dynamical parallax for the system 𝜋 𝐷𝑦𝑛 = 8.24 ± 0.15 mas, which lies in between the measurements of Hipparcos-2 (8.29±0.97 mas) and Gaia DR3 (8.4806±0.4863 mas), while the parallax from Gaia DR2 (20.0561 ± 1.1615 mas) is far from being accurate. This can be explained by the fact that the Gaia telescope has a higher resolution than that of Hipparcos. Based on the fundamental parameters of the binary system components and their positions on the evolutionary tracks, we conclude that the system consists of A7.5 and F1 solar-metalicity mainsequence stars with an age of 0.708 Gyr. Fragmentation is proposed as the most likely scenario for the formation and evolution of the system.

We present detailed analyses of eight triple stellar systems (lying between 20 and 155 pc) and nine quadruple stellar systems (lying between 20 and 250 pc) with different configurations. Most of these systems are hierarchical. The systems are HIP 4239, HIP 5588, HIP 11072, HIP 12548, HIP 13498, HIP 17895, HIP 19915, HIP 22607, HIP 25240, HIP 28614, HIP 41171, HIP 51255, HIP 51966, HIP 54611, HIP 78977, HIP 89234, and HIP 111805. We followed a method that can be applied to all multiple stellar systems, including the main sequence and subgiant evolutionary stages, to obtain their masses, ages, and atmospheric and fundamental parameters. These parameters were assured by the combined analysis of the astrometric measurements, photometric measurements, dynamical analysis, synthetic photometry, metallicity, and positions of the components on the H-R diagram. The estimated individual masses are of higher accuracy than those given by the dynamical solutions and listed in the MSC. The results show that all components of each of these systems have precisely the same age and metallicity. This ensures that fragmentation is the most probable theory for the formation of these multiple stellar systems. A quadratic fit was calculated for the mass–luminosity relation of the main-sequence subset components. We found that the primary component in all of these systems has evolved off the main-sequence stage, and some of these stars have already entered the subgiant stage.