arXiv subjects

Yuri Balega

Publications and source records attributed to Yuri Balega.

3 recordsLinked to original sources

arXiv2026

Long-term speckle interferometric monitoring of binary systems II: 2007-2025 positional measurements and improvement of orbits

This article is focused on the analysis of observational data and improvement of orbital solutions of 8 objects. The listed objects are members of a sample of approximately 300 nearby (d < 100 pc) multiple systems compiled for long-term monitoring at the 6-meter telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. Speckle interferometric observations were carried out from 2007 to the present, which corresponds to 19 years of monitoring of the systems. Therefore, the new measurements are more numerous than or comparable to those in the literature, which makes it possible to make the observation series more complete. A long observation series made it possible to cover from 20% to 70% of the phases of the orbital periods of the objects under study. In combination with previously published data, the percentage of orbital coverage by measurements ranged from 45% to 85%. As a result, 4 orbits were classified as "definitive", one as "good", 2 as "reliable", and one as "preliminary" according to a grading scheme suggested by W.I. Hartkopf et al. Despite the high grades of the orbital solutions, it is recommended to continue monitoring (in particular, to obtain periastron observations) for HIP 1055, HIP 2532, HIP 15633, HIP 19472 and HIP 20751 in order to derive the final orbital parameters. It is not possible to obtain an accurate orbital solution for HIP 20227 due to measurements whose assigned weight strongly influences the period value, and for HIP 21710(Aa,Ab) due to the long orbital period (Porb > 200 yr) and, consequently, the lack of observational data. An analysis and comparison of the mass sums and masses of components obtained by two independent methods and based on several parallax values were also carried out. In most cases, the best agreement is found between fundamental parameters calculated using Gaia parallaxes, if available.

astro-ph.SR↗

arXiv2009

First spatial resolution of the stellar components of the interacting binary CH Cygni

We report the first resolved bispectrum speckle interferometry of the symbiotic binary CH Cyg. The measured component separation, $ρ=42 \pm 2$ mas, is consistent with the one derived from the known spectroscopic orbit and distance. In particular, our result implies a total mass of the binary of $M_{\rm t}=M_{\rm g}+M_{\rm wd}=3.7^{+3.5}_{-1.7} \rm M_{\sun}$, which is in good agreement with the value $M_{\rm t}=2.7^{+1.2}_{-0.6} \rm M_{\sun}$ derived from the spectroscopic orbit solution for the red giant and evolutionary contraints. We also show that the radio jets and the bipolar outflow are not orthogonal to the orbital plane of the binary system.

astro-ph.SR↗

arXiv1999

Bispectrum speckle interferometry of the Orion Trapezium stars: detection of a close (33 mas) companion of Theta1 Ori C

We present bispectrum speckle interferometry observations with the SAO 6 m telescope of the four brightest stars in the Orion Trapezium. Diffraction-limited images with an unprecedented resolution lambda/D of 57 mas and 76 mas were obtained in the H- and K-band, respectively. The The H and K images of Theta1 Ori C (the star responsible for the proplyds) show for the first time that Theta1 Ori C is a close binary with a separation of only 33 mas (H-band observation). The sub-arcsecond companions of Theta1 Ori A and Theta1 Ori B reported by Petr et al. (1998) are confirmed. We use the magnitudes and colors of the companions to derive information about their stellar properties from the HR-diagram. In addition we briefly discuss the multiplicity of the Trapezium stars. Considering both, the visual and the spectroscopic companions of the 4 Trapezium stars, there are at least 7 companions, i.e. at least 1.75 companions per primary on average. This number is clearly higher than that found for the low-mass stars in the Orion Nebula cluster as well as in the field population. This suggests that a different mechanism is at work in the formation of high-mass multiple systems in the dense Trapezium cluster than for low-mass stars.

astro-ph↗