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Here you would find a brief summary of the most important results of
scientific research carried out by our researchers during the last year,
presented by the observatory to the Department of Physical Sciences
of the RAS.
Access here the archives of our results from 1993.
Metagalaxy
Detection of color variability of the optical polarization of the blazar BL Lac
Considering the first results of X-ray polarimetry of blazars and extensive discussion on physical processes in relativistic jets of active nuclei, interest in multi-wavelength polarimetry of objects like BL Lac has now increased. This paper presents the results of multi-band optical observations of the well-known blazar BL Lac (z = 0.069) in polarized light obtained with the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences in 2020-2022. It is shown that the emission of the object, regardless of the phase of its activity, is characterized by intraday variability of brightness and polarization with changes occurring on a time-scale of up to 1.5 hours without any designated period. It is important that the polarization color shows variability on an hour scale. The observation results confirm that the object BL Laceratae exhibits the anti-correlation between brightness and degree of polarization that is qualitatively described by the shock-wave model in a turbulent jet plasma. For the first time, the dependence of the polarization color on the phase of the object activity was discovered, which indicates the dominance of different physical processes in the plasma and, together with the rapid variability of the polarization color, challenges modern numerical calculations.
Authors:
Shablovinskaya E.S., Malygin E.A., Oparin D.V. (SAO RAS)
Published:
Shablovinskaya E., Malygin E., Oparin D.; Chromatic optical polarization of BL Lac: while faint and bright, MNRAS, 519, 3, 3798-3810, 10.1093/mnras/stac3775 (2023)
Details
Detection and study of the optical flare that accompanied GRB 210619B, and the object model
In the night of June 19-20, 2021, the 9-channel Mini-MegaTORTORA (MMT-9) system detected a bright (~10 magnitude) optical flare that accompanied one of the most powerful and distant (at a distance of 10 billion light years) gamma-ray bursts GRB 210619B. Its emission was observed simultaneously by four MMT-9 lenses with the 1, 5, 10, and 30 seconds temporal resolution in white and green (V band) light. Somewhat earlier, this event was detected by the telescopes: D50 of the Czech Academy of Sciences (Ondřejov) and FRAM-ORM (La Palma) with a temporal resolution of 10 and 20 seconds, respectively. The high temporal resolution in the MMT-9 observations made it possible to compare the fine temporal structure of the gamma-ray burst GRB 210619B itself with its behavior in the optical range. And if the hard radiation was a set of bursts of the second duration, then such details were reliably absent in the synchronous optical light curve, which for the first time became direct evidence of the implementation of the “reverse shock” model in the burst. This conclusion was supported by the peculiarities of the optical spectrum evolution of GRB 210619B discovered during the simultaneous detection of its radiation by the MMT-9, D50, and FRAM-ORM detectors in various intervals of the optical range. The unique data obtained in this study, combined with the results of observations of the Swift and Fermi gamma-ray telescopes, and based on the theoretical analysis carried out jointly with a group of Italian astrophysicists (GSSI, INFN, INAF, and UNIMIB) have allowed us to establish that out of 900 gamma-ray bursts with optical companions of GRB 210619B is clearly associated with a narrow ejection of matter during the collapse of a massive star propagating in a very rarefied interstellar medium at almost the speed of light, and its optical emission is due to the shock wave generated, when this ejection collides with the interstellar gas and moving in the opposite direction to the source of gamma-burst.
Authors:
Oganesyan G., Karpov S., Beskin G., Ivanov E., Perkov A., Lyapsina N. In cooperation with O. Salafia (INAF-OAB), M. Jelínek (ASU CAS), S. Ronchini (GSSI), B. Banerjee (GSSI), M. Branchesi (GSSI), J. Štrobl (ASU CAS), K. Polášek (ASU CAS), R. Hudec (ASU CAS), E. Katkova (RPC ``PSI``, JSC), A. Biryukov (SAI MSU), V. Sasyuk (KFU), M. Mašek (CEICO), P. Janeček (CEICO), J. Ebr (CEICO), J. Jurišek (CEICO), R. Cunniffe (CEICO), M. Prouza (CEICO)
Published:
Oganesyan G., Karpov S., Salafia O. S., Jelínek M., Beskin G., Ronchini S., Banerjee B., Branchesi M., Štrobl J., Polášek C., Hudec R., Ivanov E., Katkova E., Perkov A., Biryukov A., Lyapsina N., Sasyuk V., Mašek M., Janeček P., Ebr J., Exceptionally bright optical emission from a rare and distant gamma-ray burst, 2023, Nature Astronomy, Volume 7, p. 843-855
DOI: 10.1038/s41550-023-01972-4
Details
Archive of achievements, Metagalaxy sector
Galaxy
New asynchronous polar discovered
Polars are close binaries consisting of an accreting magnetic white dwarf (hereinafter referred to as a WD) and a cool donor star (usually an M dwarf). The strong magnetic field of a WD (10-100 MG) makes these systems synchronous, i.e., leads to equality of the WD rotation period Pspin and the orbital period Porb. However, among the polars, there is a small group of asynchronous polars (8 systems with candidates are known) exhibiting asynchrony <3%. The nature of the asynchrony remains unclear, but it has been suggested that it may be due to the recent Nova explosion. Our work has supplemented the list of asynchronous polars with the system SDSS J085414.02+390537.3. We discovered its asynchrony from the analysis of ZTF photometry, in which different periods Porb and Pspin are distinguished as well as the beat period Pbeat (1/Pbeat = 1/Porb - 1/Pspin). The corresponding polar asynchrony is 0.3%. The system shows signs of a change in the main accreting pole, which are difficult to detect in previously known systems. The spectra of the polar obtained at the BTA telescope with the SCORPIO-1 and -2 instruments demonstrate Zeeman splitting of hydrogen lines and cyclotron harmonics, the modeling of which gives an estimate of the WD magnetic field B = 28-34 MG.
Authors:
Kolbin A. I., Suslikov M. V., Kochkina V. Yu., Borisov N. V., Burenkov A. N., Oparin D. V. (SAO RAS)
Published:
Kolbin A. I., Suslikov M. V.¸ Kochkina V. Yu., Borisov N. V., Burenkov A. N., Oparin, D. V. SDSS J085414.02+390537.3 – a new asynchronous polar, 2023, Astronomy Letters, Volume 49, Issue 8, p.475-485, DOI: 10.1134/S1063773723080029
Multi-frequency studies of the giant radio burst of the Black hole X-ray binary GRS1915+105 at time scale from 9 minutes to 9 days
In the multi-frequency (2-30 GHz) studies of an X-ray binary star with a black hole (BH), the prototype microquasar GRS 1915+105 with the RATAN-600 radio telescope, an extremely bright burst after the source transition to an extremely low and hard X-ray state was detected. The brightness of the burst reached 5.5 Jy at the frequency 2.3 GHz (that is, the radio luminosity increased up to 1035 erg/s) which is higher than the values received over 30 years from the date of discovery of the object. Then, for the first time, we traced the evolution of the flare at two frequencies 4.7 and 8.2 GHz in the new multi-azimuth (MA) observation mode of the telescope, when measurements were carried out every 8.6 minutes 31 times daily. The radio flare was accompanied by a gradual increase of the soft X-ray flux (MAXI, 2-20 keV). In the optically thin radio spectrum of the synchrotron electron radiation, the spectral index smoothly changed from +0.15 to -0.95 over the first eight days. The detected flux variations at times from 30 to 300 minutes correspond to the physical size of the radiation region from 4 to 40 astronomical units probably inside the jet emission. In eight MA measurements, for the first time quasi-periodic oscillations with an amplitude of up to 10% of the average flux were discovered on time intervals from 30 to 100 minutes. This giant flare in GRS1915+105 could be associated with formation of relativistic jet emission during the decreasing accretion, when, as has recently become known, a strong disk wind simultaneously obscures the main X-ray flux and reduces the rate of accretion. The obvious similarity of the burst event in GRS1915+105 with giant bursts in microquasars Cyg X-3, SS433, and Swift J1727.8-1613 implies similar physical processes of accretion onto black holes of stellar masses.
Over the 30-year history of studying the GRS1915+105, for the first time we have encountered an extremely unusual burst phenomenon in the X-ray binary system, that sheds light on the physics of accretion onto black holes of stellar masses and the formation of powerful collimated jets.
Authors:
Trushkin S.A., Bursov N.N., Shevchenko A.V., Tsybulev P.G., Nizhelsky N.A. (SAO RAS)
Published:
ATel #15974, #16008; #16168, HEA-2023
Discovery of the first candidate ultraluminous X-ray source with a neutron star with a field of 1012 G in a 1 billion-year-old star cluster
Analyzing data from the Chandra X-ray Observatory archive, we revealed signatures of an absorption line at ≈8 keV with a width-to-energy ratio of σ/E ≈ 0.2 in the spectrum of the ultraluminous X-ray source NGC5474 X-1 taken during an outburst, when the object's X-ray luminosity reached ≈2×1040 erg/s. It has been suggested that this broad line may be a cyclotron resonant scattering feature produced by transitions of electrons between Landau levels in magnetic field. This implies that the accretor in NGC5474 X-1must be a neutron star with a magnetic field of about 1012 G. The Hubble Space Telescope data shows that the X-ray outburst of the object was accompanied by more than 13 times increase of its U band flux. Optical observations of NGC5474 X-1 carried out in its faint state have allowed us to impose restrictions on the donor star mass (< 7 solar masses), as well as to reveal a star cluster of about 1 billion years old, the center of which is located at a projected distance of about 2 pc from the source. This cluster may be the parent cluster for NGC5474 X-1, but the presence of stars with an age of ~10 Myr within 300 pc around X-1 does not exclude an accidental projection of the ULX onto the old cluster.
Authors:
Vinokurov A.S., Sarkisyan A.N., Solovyeva Yu.N., Kostenkov A.E., Medvedev A.S., Fabrika S.N. in cooperation with Atapin K.E. (SAO RAS, SAI MSU)
Published:
K. Atapin, A. Vinokurov, A. Sarkisyan, Yu. Solovyeva, A. Kostenkov, A. Medvedev, S. Fabrika. NGC 5474 X-1: a neutron star ULX in an old stellar cluster?, Monthly Notices of the Royal Astronomical Society, 2023,Volume 527, Issue 4, pp.10185-10200, DOI: 10.1093/mnras/stad3719
Details
Archive of achievements, Galaxy sector
Solar system
1.3.7.4. Sun and near-Earth space, solar-terrestrial connections
1.3.7.6. Development of methods of ground-based and extra-atmospheric astronomy
Section 3. Sun; Section 11. Radio telescopes and methods
Detection of the hydroxyl (OH) absorption line in the radio emission of the solar corona
When observing the Sun with the RATAN-600 using a new high-speed spectral polarimetric complex with a frequency resolution of 0.12–8 MHz and a time resolution of 8 ms in the range of 1–3 GHz in the radio emission spectra of individual active regions (AR), an absorption line was discovered on the Sun in the frequency range of 1.5–1.65 GHz near the hydroxyl absorption line (1.7 GHz). The absorption was observed only in the emission of those ARs that were overlapped with a cool filament visible in the H-α images or on the limb in the presence of a prominence, where the existence of a hydroxyl molecule is potentially possible. The line shape corresponds to the estimated model calculations for conditions in a cool filament in the solar corona (7500 K, ~10-6 atm) taking into account the instrumental function of the 1–3 GHz spectral polarimetric complex (without taking into account the displacement due to a magnetic field). The discovery of molecular lines in the solar corona may indicate the nature of its heating and the stability of its temperature balance.
Authors:
Ovchinnikova N.E., Bogod V.M., Lebedev M.K. Ripak A.M., Storozhenko A.A., Kurochkin E.A. (SAO RAS)
Published:
1. Bogod V. M., Lebedev M. K., Ovchinnikova N. E., Ripak A. M., Storozhenko A. A., Spectroradiometry of the Solar Corona on the RATAN-600, Cosmic Research, 2023, Vol. 61, No. 1, pp. 27–33, DOI: 10.1134/S001095252301001X
2. Ovchinnikova N.E., Lebedev M.K., Bogod V.M., Ripak A.M., A.A. Storozhenko, Results of a new approach to the analysis of multi-wavelength observations data obtained with RATAN-600 The Multifaceted Universe: Theory and Observations – 2022, 23-27 May 2022, SAO RAS, Nizhny Arkhyz, Russia; published December 14, 2022. Online at https://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=425, id.7
3. Bogod V., Lebedev M., Ovchinnikova N., Ripak A., Kurochkin E., Detection of absorption in the decimeter radio emission of solar corona, The Multifaceted Universe: Theory and Observations – 2022, 23-27 May 2022, SAO RAS, Nizhny Arkhyz, Russia; published December 14, 2022. Online at https://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=425, id.5
Details
Archive of achievements, Solar system sector
Hardware and methodological developments
EXPLANATION: Exoplanet and transient events investigation project, first results
Amid the global boom of recent decades, programs of searching for and investigating extrasolar planets (exoplanets) in Russia were until recently extremely limited due to the lack of adequate scientific instruments. With funding from the Russian Science Foundation and two grants from the Ministry of Education and Science (2014-2022), SAO RAS created a complex of wide-angle robotic telescopes to search for exoplanets and non-stationary (transient) events, and a high-accuracy planetary spectrograph that allows detecting the radial velocity variations of parent stars under the influence of exoplanets. As a result, the project abbreviated as EXPLANATION (EXoPLANet And Transient events InvestigatiON) started in the Special Astrophysical Observatory of the Russian Academy of Sciences. Its goal is a massive search and study of exoplanets and non-stationary events in the Universe. In less than two years, the first ten exoplanets and exoplanet candidates were discovered within the project and studied using photometric transits and Doppler spectroscopy methods. An example of two such events is shown in Fig. 1.
Authors:
Valyavin G.G., Valeev A.F., Beskin G.M., Fabrika S.N., Galazutdinov G.A., Vlasyuk V.V. in cooperation with Yakovlev O. Ya. (SAO RAS, IKI RAS), Tavrov A.V., Korablev O.I. (IKI RAS)
Published:
1. Doppler confirmation of TESS planet candidate TOI-1408.01: grazing transit and likely eccentric orbit, Galazutdinov G.A., Baluev R.V., Valyavin G. et al, Monthly Notices of the Royal Astronomical Society: Letters, Volume 526, Issue 1, pp.L111-L115, DOI: 10.1093/mnrasl/slad127
2. Eight Exoplanet Candidates in SAO Survey, Yakovlev O. Ya., Valeev A. F., Valyavin G. G. et al., Astrophysical Bulletin, Volume 78, Issue 1, p.79-93, DOI: 10.1134/S1990341323010108
3. Exoplanet Two-Square Degree Survey With SAO RAS Robotic Facilities, Yakovlev O. Ya., Valeev, Azamat F., Valyavin, Gennady G., Tavrov, Alexander V. et al. Frontiers in Astronomy and Space Sciences, vol. 9, id. 903429, DOI: 10.3389/fspas.2022.903429
4. EXPLANATION: Exoplanet and Transient Event Investigation Project – Optical Facilities and Solutions, Valyavin G., Beskin G., Valeev A., Galazutdinov, G. et al. Photonics, Volume 9, Issue 12, id.950, DOI: 10.3390/photonics9120950
Blazar classification based on multiparameter cluster analysis
Implementing multiparameter cluster analysis for the blazars from the Roma BZCAT catalog, we developed their classification that reflects a continuous variation of properties from the BL Lac-type objects to flat-spectrum radio quasars (FSRQs).
Using world-best databases as well as multi-frequency measurements obtained with RATAN-600, we selected a set of characteristics that described the spectral energy distribution from radio waves to gamma rays, radio luminosity, and distance to a blazar. With these characteristics we carried out a multiparameter cluster analysis using two machine learning methods, which showed similar (~90%) results.
The resulting classification is validated by comparison with the known blazar types: BL Lacs, FSRQs, high synchrotron peaked blazars (HSPs), and blazars detected in the TeV range. A continuous variation of properties along the obtained groups is observed. The group of HSP blazars stands out against the overall distribution.
On this example of a sample of blazars, we demonstrate the effectiveness of the clustering technique for objective analysis of multiparameter arrays of experimental data.
Authors:
Kudryavtsev D.O., Sotnikova Yu.V., Stolyarov V.A., Mufakharov T.V., Vlasyuk V.V., Cherepkova Yu.V. (SAO RAS)
Published:
Kudryavtsev D., Sotnikova Y., Stolyarov V., et al., 2023. Acta Astrophysica Taurica, vol. 4, no. 3, pp. 5–10. DOI: 10.34898/aat.vol4.iss3.pp5-10
Archive of achievements, Instrumental and Methodological Development sector
Archive of achievements, Astronomical education sector
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