Abstract
Long-term monitoring at the 6 m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences made it possible to improve the orbits of 15 objects (HIP 689, HIP 3951, ...HIP 10438, HIP 43948, HIP 69962, HIP 95995, HIP 102029, HIP 102357, HIP 104383, HIP 105947, HIP 106255, HIP 108917, HIP 111546, HIP 113726, HIP 114922) and construct an orbital solution for HIP 65327 for the first time. Observations have been carried out since 2007; that is, the accumulated data correspond to an interval of 13 yr. As a result, most of the orbits were classified as “accurate” using the qualitative criteria by Worley & Heintz. A comparison of the mass sums and masses of the components calculated by two independent methods was made for objects with orbital solutions. The Gaia EDR3 parallax was used to obtain the fundamental parameters, as well as the Hipparcos and Gaia DR2 parallaxes.
ABSTRACT
We report on the occultation of the star TYC 1947-290-1 by the asteroid (87) Sylvia. While asteroidal occultations occurring at fixed professional-level locations are relatively rare and are ...only recently starting to be observed with sufficiently high time resolution and sensitivity, they have the capability to measure sub-milliarcsecond angular diameters. The event described here was especially outstanding because the star was revealed to be a small-separation binary (≈10 mas at discovery), while at the same time the asteroid is not only one of the largest in size but it also has two satellite moons. The observations were carried out at the Russian 6-m telescope in 2019 December, and initially consisted of both a fast photometric series of the occultation itself, as well as of extensive speckle interferometry of the star and asteroid in the time immediately before and after the occultation. Subsequently, we obtained speckle data of TYC 1947-290-1 over a period of 1 yr after the event. We are able to present a detailed study of the binary star including measurements of the angular diameter of the stellar components, their geometry, and relative fluxes over several bandpasses, and to provide an accurate determination of the size of (87) Sylvia. We emphasize that we have been able to obtain the smallest ever directly measured stellar diameter, below the 100 micro-arcsecond level. Our data are also suitable for imaging of the asteroid by speckle holography, a task which we intend to carry out in a separate work.
The orbits of eight systems with low-mass components (HIP 14524, HIP 16025, HIP 28671, HIP 46199, HIP 47791, HIP 60444, HIP 61100, and HIP 73085) are presented. Speckle interferometric data were ...obtained at the 6 m Big Telescope Alt-azimuth Special Astrophysical Observatory of the Russian Academy of Sciences (BTA SAO RAS) from 2007 to 2019. New data, together with measures already in the literature, made it possible to improve upon previous orbital solutions in six cases and to construct orbits for the first time in the two remaining cases (HIP 14524 and HIP 60444). Mass sums are obtained using both Hipparcos and Gaia parallaxes, and a comparison with previously published values is made. Using the Worley & Heintz criteria, the classification of the orbits constructed is carried out.
ABSTRACT
We have initiated a program to systematically observe lunar occultations from the SAO RAS 6-m telescope (BTA). So far, 25 events have been recorded with some of them leading to accurate ...measurements of angular diameters in late-type stars and of binary stars. One interesting aspect is that the observations are carried out by the same group and with the same equipment dedicated also to speckle interferometry, so that many of the target objects are being investigated by two independent and complementary techniques almost simultaneously. This represents a novel approach with a potential to provide more complete and extended results than possible until now. In this paper we focus on a general description of the scientific aim and methods, and we provide an overview of the results including an assessment of the quantitative performance, showing that milliarcsecond resolution is achieved on sources as faint as ≈12 mag. Among the sources we discuss in detail are the binary stars SAO 98270 and μ Cet, and the resolved late-type stars 74 Gem, DE Psc, and IRC+00213. Other stars with positive results are the subject of dedicated papers. We foresee to continue routine observations with this facility in the immediate future, and to coordinate with other observatories equipped with similar instrumentation.
We have recorded three lunar occultations of Aldebaran (a Tau) at different telescopes and using various band-passes, from the ultraviolet to the far red. The data have been analysed using both ...model-dependent and model-independent methods. The derived uniform-disc angular diameter values have been converted to limb-darkened values using model atmosphere relations and are found in broad agreement among themselves and with previous literature values. The limb-darkened diameter is about 20.3 mas on average. However, we have found indications that the photospheric brightness profile of Aldebaran may have not been symmetric, a finding already reported by other authors for this and for similar late-type stars. At the sampling scale of our brightness profile, between 1 and 2 mas, the uniform and limb-darkened disc models may not be a good description for Aldebaran. The asymmetries appear to differ with wavelength and over the 137-d time span of our measurements. Surface spots appear as a likely explanation for the differences between observations and the models.
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The article presents new results on motion modeling and creation of ephemeris of satellites of asteroids based on observations. In previous work on the project, ephemeris of 62 satellites were ...built. Since then, new satellites of asteroids have been discovered and new observations have been published. The article gives the orbital parameters of four new satellites found from observations. Satellite ephemeris updates based on new observations are reported. An important and necessary characteristic of ephemeris is their accuracy. In this paper, we show how ephemeris accuracy estimates are made, and examples of estimates are given. An important circumstance has been revealed: for a large number of satellites, the accuracy of ephemeris has degraded by now to such an extent that the ephemeris have become practically unusable. There is an urgent need for new observations of satellites of asteroids.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Based on the speckle observations of the wide double star ADS 15571 with the 6-m BTA telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences in 2014, we have confirmed ...the existence of a close companion to component A that was previously detected from astrometric observations at the Pulkovo Observatory. An extension of the BTA observations from 2014 to 2022 has allowed 28 positions of the companion relative to the primary star to be obtained. From this series we have constructed the relative orbit of the companion and determined the sum of the masses of subsystem A (
). A comparison of this orbit with the orbit of the photocenter of component A constructed from Pulkovo photographic observations has also allowed the mass ratio of the primary star and the companion and their individual masses to be estimated:
and
. Based on the estimates of the magnitude difference between the two stars of the system ADS 15571A, we have estimated the spectral types of the components: ADS 15571Aa—F8V; ADS 15571Ab—K5V–K5.5V. The speckle observations of component B have shown that it has no resolvable companions.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
8.
HD 52721 as a Quadruple System Obolentseva, M. A.; Dyachenko, V. V.; Pogodin, M. A. ...
Astrophysical bulletin,
07/2021, Volume:
76, Issue:
3
Journal Article
Peer reviewed
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We present the study of the multiple system HD 52721 by means of speckle interferometry in 2019–2020 at the 6-m telescope of the SAO RAS. Formerly, HD 52721 was known as triple (
(B2V + B2V;
) +
;
...). In our work, the system is resolved as a speckle interferometric triple system, i.e., the total system multiplicity increased up to four components (
(B2Ve;
)+
(B9VХ,
);
). We have used the reference-dependent and reference-independent methods for measuring positional parameters and magnitude differences between the components. The obtained measurements of the brightness differences agree with the observed light curve of the eclipsing pair.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present a brief description of a joint Russian-Korean project abbreviated as EXPLANATION (EXoPLANet And Transient events InvestigatiON). The project is aimed at a massive photometric, ...speckle-interferometric, spectral, and radio bolometric search for non-stationary events in the Universe, as well as the study of exoplanets. The core of the project consists of several 0.07–2.5-m optical telescopes, 6-m telescope BTA and a six-hundred-meter radio telescope RATAN-600 of the Special Astrophysical Observatory of RAS (Russia), Moscow State University observatory (Russia), Kourovka Observatory (Russia), Crimean Astrophysical Observatory (Crimea), Korea Astronomy and Space Science Institute (Republic of Korea). We discuss the philosophy of the project and its instrumentation, as well as the first obtained results. In this paper we report the results related to the detection of several types of transient events and the study of exoplanets.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
One of the goals of the Pulkovo program of research on stars with large proper motions is to reveal among the low-luminosity stars those that have evidence of binarity. Twelve astrometric binary ...candidates from the Pulkovo list have been included in the program of speckle observations with the BTA telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) and the 2.5-m telescope at the Caucasus Observatory (CO) of the Sternberg Astronomical Institute of the Moscow State University to confirm their binarity and then to determine the parameters of the revealed stellar pairs. The binarity of the brightest of these stars, J1158+4239 (GJ 3697), has been confirmed. Four sessions of speckle observations with the BTA SAO RAS telescope and one session with the 2.5-m CO telescope have been carried out in 2015–2016. The weighted mean estimates of the pair parameters are
ρ
= 286.5 ± 1.2 mas and
θ
= 230.24◦ ± 0.16◦ at the epoch B2015.88248. The magnitude difference between the pair stars is Δ
m
= 0.55 ± 0.03 (a filter with a central wavelength of 800 nm and a FWHM of 100 nm) and Δ
m
= 0.9 ± 0.1 (an R filter).
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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