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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.
Solar system
Archive of achievements, Solar system sector
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(по) 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
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 MB≈-10
and the virial mass Mvir≈109M☼.
We have found that the standard ΛCDM model accurately describes
the distribution function of galactic circular velocities for massive
objects (Vcirc≥70 km/s and
Mvir≥5x1010M☼),
but five times overestimates the number of dwarf
galaxies with circular velocities Vcirc~30-40 km/s. Such a considerable overabundance of
predicted large dwarf galaxies with masses
Mvir≈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 (Slim>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
2h≤RA≤6h.
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
Archive of achievements, Astronomical education sector
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