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Scientific achievements, Galaxy sector


Detection of two new LBV stars.
In two exterior galaxies new luminous blue variable stars (LBV) were observed. They are the most massive stars at an evolutionary stage just before a supernova burst. In M33 galaxy it is the seventh LBV having a luminosity of ~2x106L, mass ~100M, temperature ~16000K, temperature of two dust components of the star 900K and 420K. Near the dwarf galaxy DDO 68 it is the first LBV with an absolute star magnitude of MV ~ -7m and a very low metallicity (Z=1/36Z). Study of this star will allow putting limits on the models of evolution of massive stars in the early Universe.
(For contacts: S.N.Fabrika and S.A.Pustilnik).

G89-14 - quaternary system with the lowest metallicity
By means of a speckle interferometry method with BTA telescope it was detected that a sub-dwarf system G89-14 with [m/H]=-1.9 situated in a halo of the Galaxy consists of four components (MA~0.67, MB~0.24, MC~0.33, MD~0.22 solar masses) and that it is a system with the lowest metallicity among all known quaternary stars. It shows that the system was forming in an environment with a low metal concentration. Orbital period ratio for the quaternary system is P1:P2:P3=0.52:3000:650000 years, which points at a high hierarchical organization and a stability of the system. Existence of such objects proves systems with high multiplicity to be able to remain throughout dynamic evolution for the time comparable to the age of the Galaxy.
(For contacts: D.A.Rastegaev).

Fast deceleration of rotation of a magnetic star with a strong field HD 37776.
31 years of observations of the magnetic star HD 37776 resulted in detecting deceleration of its axial rotation for 17.7±0.7s (dP/P = 4.0x10-6 per year). The star has a very strong magnetic field ( ~70-80 kGs on surface) of complex configuration, its age is no more than 1 billion years. The star is surrounded by a nebula. It is supposed that a magnetic deceleration is present (at least in its outer layers), the deceleration is caused by loss of angular momentum through a solar wind which is controlled by a magnetic field. It is the first case of magnetic deceleration detection for a chemically peculiar star on the main sequence.
In cooperation with Institute of Theoretical Physics and Astrophysics, Astronomical Institute and Technical University (Czech), The University of Tennessee (USA), Astronomical institute (Slovakia), Herzberg Institute of Astrophysics (Canada), University of Zagreb (Croatia), Rojen National Astronomical Observatory (Hungary).
(For contacts: I.I.Romanyuk).

Optical observations of an isolated neutron star.
Through international cooperation (Russia, Spain, Germany, South Africa, Chili) observations of optical emission from a SWIFT event J195509+261406 had been carried out during three days. It was demonstrated that this event was neither a classic gamma-ray burst nor a black hole in a binary system nor a micro quasar. It corresponds more to a model of isolated neutron star with abnormally strong magnetic field ~1015Gs (magnetar in its active phase). A variability of optical emission of a soft gamma-repeater is detected. It was shown that this event represents a "bridge" in luminosity scale between abnormal X-ray pulsars and faint isolated neutron stars.
In cooperation with international group of researchers (coordinator A.Castro-Tirado, Spain).
(For contacts: T.A.Fatkhullin).

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Last update: 27/08/2012