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Scientific achievements, Galaxy 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
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
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)
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.

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