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1.
Izmailov I. S. Shakht N. A. Polyakov E. V. Gorshanov D. L. Pogodin M. A. 《Astrophysics》2021,64(2):160-171
Astrophysics - This paper is a continuation of our earlier work devoted to determining the orbit and mass of the star 61 Cyg and the changes in the photometric characteristics of its components.... 相似文献
2.
Stars in the Pulkovo Observatory program are observed with a 65-cm refractor during many years to study their positions and movements. We present examples of two visual binary stars, for which orbits and masses of components were determined, and two astrometric stars, for which masses of their unseen companions were estimated. The first two stars are ADS 14636(61 Cygni) and ADS 7251,and the others are Gliese 623 and ADS 8035(Alpha UMa). Direct astrometric methods are used for estimation of mass-ratio and masses. 相似文献
3.
N. A. Shakht L. G. Romanenko D. L. Gorshanov O. O. Vasilkova 《Solar System Research》2016,50(1):56-66
A list of selected binary stars is presented that have been observed for several decades using a 26-inch refractor at the Pulkovo Observatory. These stars are at a distance from 3.5 to 25 pc from the Sun. They belong to spectral classes F, G, K, and M. Their masses range from 0.3 to 1.5 solar masses. We have analyzed them as possible parent stars for exoplanets taking into account the physical characteristics of these stars. In view of dynamic parameters and orbital elements that we have obtained by Pulkovo observations, ephemerides of positions for the coming years are calculated. The boundaries of the habitable zones around these stars are calculated. The astrometric signal that depends on the gravitational influence of hypothetical planets is estimated. Space telescopes for astrometric observations with microsecond accuracy can be used to detect Earth-like planets near the closest stars of this program. This paper presents an overview of astrometric programs of searches for exoplanets. 相似文献
4.
This article is devoted to the Pulkovo astronomer, Prof. Aleksandr Nikolaevich Deich (Deutsch) (1899-1986), on the 110-th
anniversary of his birth. Deich is known as the founder of the Pulkovo program for observing stars with invisible companions,
as well as for his research on the star 61 Cyg, which was suspected, in his time, of having invisible companions with the
masses of planets. Astrometric observations on the long focus astrograph and searches for exoplanets of nearby stars are reviewed.
Modern methods of searching for exoplanets are summarized briefly. Instrument designs proposed by astronomers at Kharkiv (Scientific
Research Institute of Astronomy at Kharkiv National University, NIIA KhNU) and Kazan (Institute of Astronomy, Kazan State
University, AO KGU) for use in the search for low-mass dark components of stars are discussed. Examples are given of confirmations
of invisible companions of stars which were first discovered by observation. A number of theoretical results on this topic
from Kharkiv National University (Scientific Research Institute of Astronomy at Kharkiv and the Dept. of Astronomy) are noted. 相似文献
5.
A. A. Kiselev O. V. Kiyaeva I. S. Izmailov L. G. Romanenko O. A. Kalinichenko O. O. Vasil’kova T. A. Vasil’eva N. A. Shakht D. L. Gorshanov E. A. Roschina 《Astronomy Reports》2014,58(2):78-97
The results of long-term, uniform, photographic observations of visual double and multiple stars obtained on the Pulkovo 26″ refractor are presented. Relative positions are calculated for 259 pairs of visual double stars in 194 systems, with the relative motions also computed for 127 pairs. Lower limits for the total masses of the systems for which elliptical orbits possible are also found for 48 pairs with reliable parallaxes from the Hipparcos catalog. The accuracies of the three measuring machines used in the reduction of the photographic plates are compared. Component separations measured with different machines can differ by as much as 0.2″, demonstrating the advantages of using uniform observations. 相似文献
6.
S. D. Buliga V. I. Globina Yu. N. Gnedin T. M. Natsvlishvili M. Yu. Piotrovich N. A. Shakht 《Astrophysics》2011,54(4):548-552
The spin of central black holes with intermediate masses in globular clusters is determined using the well known relationship
between the kinetic power of a relativistic jet and the observed radio luminosity of the region closest to a central black
hole. The estimate of the magnitude of the spin is based on the known Blandford-Znajek mechanism. The magnetic field near
the event horizon of a black hole is determined using a magnetic coupling mechanism that assumes equality between the densities
of the magnetic and kinetic energies of the accreting gas (the Magnetic Coupling Model). The rate of accretion [(M)\dot] \dot{M} is derived on the basis of the Bondi-Hoyle mechanism. 相似文献
7.
8.
Results from an analysis of a forty year series of photographic observations of the binary star 61 Cyg on the 26 inch refractor
at the Pulkovo Observatory are presented. The orbit is constructed and the sum of the masses of the components is determined
from the relative positions of the components. A study of the individual motions of the components of 61 Cyg relative to the
surrounding stars yields their mass ratio and the masses of the main and secondary components, 0.74 and 0.46 solar masses,
respectively. The relative motion of the components is found to have a fluctuating component with a period of 6.5 years which
may be caused, in particular, by the presence in the system of a dark, low-mass companion.
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Translated from Astrofizika, Vol. 49, No. 3, pp. 453–465 (August 2006). 相似文献
9.
I. S. Izmailov E. A. Roshchina A. A. Kiselev T. P. Kiseleva O. A. Kalinichenko O. P. Bykov O. V. Kiyaeva L. G. Romanenko N. A. Shakht K. L. Maslennikov T. A. Vasil’eva 《Astronomy Letters》2016,42(1):41-54
We present the results of determining the relative positions of 359 pairs of stars. More than 6000 photographic plates were obtained in 1960–2007 at the 26-inch refractor of the Pulkovo Observatory. The plates have been digitized with a Canon EOS 5D Mark II digital camera and a long-focus Jupiter 21M lens; the scalewas 21 μm/pixel. Themeasurements have been calibrated using a template digitized with the Belgian high-precision ROB Digitizer. The results have been thoroughly investigated for systematic errors. We have studied the scale of the 26-inch refractor and revealed its temperature and time dependences. The application of a new digitization, measurement, and calibration technique has allowed the accuracy to be increased compared to the past measurements. The single-exposure measurement accuracy is within the range from 2 to 70 mas, on average, 28 mas in both coordinates. The errors of the yearly mean positions are, on average, 8.7 mas in the angular separation and 0.05?. in the position angle. 相似文献
10.
A. A. Kiselev Yu. N. Gnedin N. A. Shakht E. A. Grosheva M. Yu. Piotrovich T. M. Natsvlishvili 《Astronomy Letters》2008,34(8):529-536
Using the technique of determining the sum of the masses of double stars, we have estimated the mass of the central object in the globular cluster M15. The radial velocities of stars at distances up to 1″ from the cluster center have been used. The parameters of circular orbits and the space velocities of 11 selected field stars relative to the cluster center have been determined from the calculated velocity dispersions with respect to the mean radial velocity. Based on the mean space velocity V, 14 km s?1, and using the energy integral, we have estimated the mass of the central object to be within the range (1?9) × 103 M ⊙. We have estimated the kinetic power of the outflow of matter from the region surrounding the black hole in M15 and the specific angular momentum of the black hole. 相似文献