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Scientific achievements in 2015

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.

Solar system

Archive of achievements, Solar system sector

Galaxy

Detection of a Very Slow Magnetic Rotator HD 965
Based on the measurements of the magnetic field of the chemically peculiar star HD 965, conducted in 2000-2015 with the SAO RAS 6-m telescope, we have found that this object is an ultraslow magnetic rotator with a rotation period of about 20 years. HD 965 is one of the three very slow rotators among more than 300 studied CP stars. Thus, very slow rotation is a very rare but not unique phenomenon. The occurrence of three such rotators means that the dynamo mechanism is not efficient during the life of a peculiar star on the main sequence and cannot generate a large-scale magnetic field. The generation occurs at early evolutionary stages before the arrival of the star on the main sequence.
Authors: I.Romanyuk , D.Kudryavtsev, E.Semenko, I.Yakunin
Published:
I.Romanyuk, D.Kudryavtsev, E.Semenko, I.Yakunin, Magnetic Field Monitoring of the Very Slowly Rotating CP Star HD 965, 2015, Astrophysical Bulletin, 70, 4, 482

Detection of a Uniquely Bright Radio Flare in the X-Ray Binary Star with a Black Hole V404 Cygni (GS2032+336)
The optical nova and X-ray binary V404 Cyg, consisting of a black hole with a mass of 10M_☼ and a K0 subgiant with a mass of 0.6M_☼ which fills its Roche lobe, was studied from June 18 to July 12, 2015 with the RATAN-600 radio telescope in the range from 2.3 to 22 GHz. In this period, the V404 Cyg radio spectrum was cardinally changing along with the flux measurements in the range of 15-300 keV (Swift/BAT and Integral). On June 26, two hours later an X-Ray flare of 50 Crab, the radio flux increased 40 times up to 4 Jy per day. It was concluded that it was the very beginning of the formation of a relativistic jet ejection from the poles of the accretion disk at the time of near-critical accretion of matter on the black hole.
Authors: S.Trushkin, N.Nizhelskij, P.Tsybulev
Published:
1. Trushkin S.A., Nizhelskij N.A., Tsybulev P.G, The Inverted Radio Spectrum of the Flare in V 404 Cyg, The Astronomer's Telegram, 2015, #7667
2. Trushkin S.A., Nizhelskij N.A., Tsybulev P.G., A New Giant Radio Flare of V404 Cyg at Centimeter Wavelengths, The Astronomer's Telegram, 2015, #7716

Detection of an OH Maser Flare in the Nebula W3
Observing OH masers at a frequency of 1665 MHz in the source W3(ïî) with the 32-m antenna of the Svetloe Radio Astronomy Observatory (IAA RAS), we detected a radiation burst in the right circular polarization at a radial velocity of -46.2 km/s at UT 03:27 on January 23, 2012. At that moment, the radiation flux increased 7 times in 90 seconds and then decreased down the previous level. Such a time gives an estimate of the maser spot linear dimension of 0.18 AU (2.7X10¹² cm). In 2013-2014, we found intensity variations of the components at -47.6 and -45.1 km/s with characteristic times of the order of 10 hours, moreover, the variations of the right and left polarization fluxes were evidently anticorrelated. Such phenomena in the OH maser research are discovered for the first time and have not been explained by any maser variability models.
Authors: I.Gosachinskij, ogether with S.Grenkov, A.Ipatov, I.Rakhimov (IAA RAS)
Published:
The results were reported at the 32th All-Russian Conference "Actual Problems of Extragalactic Astronomy", April 20-23, 2015, Pushchino, and at the 13th Russian-Finnish Symposium on Radio Astronomy, May 25-29, 2015, Saint Petersburg, I.Gosachinskij, S.Grenkov, A.Ipatov, I.Rakhimov, An OH Maser Flare in the Nebula W3, "Astronomy Letters", submitted to the journal.

Archive of achievements, Galaxy sector

Metagalaxy

Explanation of the Origin of Ultraluminous X-Ray Sources
Using optical spectroscopy, we revealed the origin of unusual objects: ultraluminous X-ray sources in other galaxies, which radiate in the X-ray range thousands times stronger than the black holes in our Galaxy. It turned out that these objects are supercritical accretion disks in binary systems with black holes, similar to the supercritical accretor in our Galaxy, SS433, being at the short-term stage of supercritical accretion.
Authors:
S. Fabrika , A.Vinokurov, O.Sholukhova
Published:
S.Fabrika, Y.Ueda, A.Vinokurov, O.Sholukhova, M.Shidatsu, Supercritical Accretion Disks in Ultraluminous X-Ray Sources and SS 433, 2015, Nature Physics, 11, 551

Detection of Considerable Lack of Massive Dwarf Galaxies in the Local Volume compared to the Standard Cosmology
The sample of about 750 galaxies in the Local Volume (distance smaller than 10 Mpc) gives a unique opportunity to study the properties of galaxies including the faintest objects: the absolute magnitude M_B≈-10 and the virial mass M_vir≈10⁹M_☼. We have found that the standard ΛCDM model accurately describes the distribution function of galactic circular velocities for massive objects (V_circ≥70 km/s and M_vir≥5x10¹⁰M_☼), but five times overestimates the number of dwarf galaxies with circular velocities V_circ~30-40 km/s. Such a considerable overabundance of predicted large dwarf galaxies with masses M_vir≈10¹⁰M_☼ in the field causes a complicated problem: to turn out to be lost, these galaxies should be of extremely low surface brightness, with no star formation processes and neutral hydrogen. Up to the present moment, there has been no such a galaxy detected.
Authors:
I.Karachentsev, D.Makarov, O.Nasonova together with A.Klypin (New Mexico State University)
Published:
Klypin A., Karachentsev I., Makarov D., Nasonova O., Abundance of Field Galaxies, 2015, MNRAS, 454, 1798

Detection of Radio Transients and Variable Radio Sources using the Archive Data of the Cold Surveys
Analyzing the data of four observational periods of the RATAN-600 Cold surveys in 1980-1994 with the calibration curves plotted using the sample of non-variable sources with steep spectra, we detected 73 sources (S_lim>20 mJy) with considerable variations of flux density, which are variable according to different statistical criteria, moreover, the variability for 52 of them was determined for the first time; 3 radio transients were also discovered as well as 22 radio sources (4%) not previously mentioned in the RCR catalog. The inference was drawn on the possible use of the observations conducted on RATAN-600 in the survey mode in order to search for faint variable sources and transients and also to study them in detail provided that synchronous multifrequency data is used.
Authors:
O.Zhelenkova), E.Majorova, A.Temirova
Published:
1. E.Majorova, O.Zhelenkova. On the Possibility of Detection of Variable Sources Using the Data of the "Cold" Surveys Carried Out on RATAN-600. Astrophysical Bulletin, Vol.67, Issue 3, pp. 318-339;
2. E.Majorova, O.Zhelenkova. Multiband Study of Radio Sources of the RCR Catalogue with Virtual Observatory Tools. Astrophysical Bulletin, Vol.68, N 4, 371-395 (2013);
3. E.Majorova, O.Zhelenkova, A.Temirova. Search for Variable Sources Using the Data of the "Cold" Surveys in the Right-Ascension Interval 2^h≤RA≤6^h. Astrophysical Bulletin, Vol.70, N 1, 34-46 (2015);
4. E.Majorova, O.Zhelenkova. Search for Variable Sources Using the Data of the "Cold" Surveys. The 30th conference "Actual Problems of Extragalactic Astronomy", Pushchino, April 8-10, 2013;
5. E.Majorova, O.Zhelenkova. Variable Radio Sources from the "Cold" Surveys Carried Out on RATAN-600. The All-Russian Astronomical Conference "Many-Faced Universe" (VAK- 2013), September 23-27, 2013, Saint Petersburg, p.174;
6. O.Zhelenkova, E.Majorova, A.Temirova. Search for Variable and Transient Sources Using the RATAN-600 Surveys in 1980-1994. "Actual Problems of Extragalactic Astronomy", the 32th conference, Pushchino, April 20-25, 2015, p.19.

Archive of achievements, Metagalaxy sector

Hardware and methodological developments

Modernization of the BAO NAS RA 1-m Schmidt Telescope
The modernization of the 1-m Schmidt telescope of the Byurakan Astrophysical Observatory (NAS of Armenia) is finished. A new control system has been created, a CCD detector (4kx4k, readout noise of 11 e, pixel size of 9 μm (0.89 arcsec), field of view of about 1 sq. degree) with fluid cooling and a set of 21 midband, 5 broadband, and 3 narrowband filters has been installed in the telescope focus. First images have been received.
Authors: S.Dodonov, V.Afanasiev, V.Amirkhanyan (SAO RAS) together with T.Movsessian, S.Balayan, V.Gabrielyan (BAO NAS RA)
The results were reported at the international conference "The Present and Future of Small and Medium-Size Telescopes" (SMT-2015), September 19-22, 2015, Nizhny Arkhyz
1. V.Gabrielyan, T.Movsessian, Modernization of the Byurakan Astrophysical Observatory 1-m Schmidt Telescope, SMT-2015 Conference Abstracts, p.36;
2. S.Dodonov, V.Afanasiev, V.Amirkhanyan, T.Movsessian, V.Gabrielyan, Spectrophotometry of Stars and Galaxies in Midband Filters with the Byurakan Astrophysical Observatory 1-m Schmidt telescope: the Instrument Possibilities and Challenges, SMT-2015 Conference Abstracts, p.44.

Archive of achievements, Instrumental and Methodological Development sector

Astronomical education

Archive of achievements, Astronomical education sector