Search Publications
Inaccuracies in the spectral classification of stars from the Tycho-2 Spectral Type Catalogue
Tsvetkov, A. S.; Popov, A. V.; Smirnov, A. A.
We compare the spectroscopic and trigonometric parallaxes of common stars from the Tycho-2 Spectral Type and Hipparcos Catalogues. This comparison has revealed that the distance estimations for the overwhelming majority of stars by both methods yield very similar results. However, there is a small fraction of stars for which the distance estimates…
Orientation of the hipparcos frame with respect to the reference frames of the DE403/LE403 and DE405/LE405 ephemerides based on asteroid observations
Chernetenko, Yu. A.
Highly accurate observations of 116 asteroids are used to determine the orientation of the Hipparcos frame with respect to the reference frames of the DE403/LE403 and DE405/LE405 majorplanet ephemerides. These observations include the photographic observations of 15 asteroids obtained as part of the programs for observing selected asteroids and re…
Searching for the host galaxy of GRB 920925C
Pozanenko, A. S.; Loznikov, V. M.; Volnova, A. A. +2 more
GRB 920925C is probably the first cosmic gamma-ray burst with an optical afterglow detected from archival data. We present the results of our observations with the Shajn mirror telescope of the Crimean Astrophysical Observatory aimed at searching for the host galaxy at the afterglow location; we have determined the boundaries of distances to the p…
Emission stratification in two-component HII regions with stellar wind
Sitnik, T. G.; Bychkov, K. V.
To explain the variety of observed optical emission stratification in the shells around Wolf-Rayet stars, we have calculated the nonstationary cooling of a homogeneous gas layer heated to a temperature (0.4-2) × 105 K. We have assumed that the nebula is ionized by its central star and consists of a rarefied gas and a set of clouds with …
The first observation of AX J1749.1-2733 in a bright X-ray state—Another fast transient revealed by INTEGRAL
Sunyaev, R. A.; Grebenev, S. A.
An intense outburst of hard radiation (with a peak flux of ∼50 mCrab) was detected from the X-ray transient AX J1749.1-2733 by the IBIS/ISGRI gamma-ray telescope onboard the INTEGRAL observatory when the Galactic center field was monitored on September 8 10, 2003. Previously, this source had never been observed in a bright X-ray state. During the …
4U 0115+63 from RXTE and INTEGRAL data: Pulse profile and cyclotron line energy
Sunyaev, R. A.; Tsygankov, S. S.; Lutovinov, A. A. +1 more
We analyze the observations of the transient X-ray pulsar 4U 0115+63 with the RXTE and INTEGRAL observatories in a wide X-ray (3-100 keV) energy band during its intense outbursts in 1999 and 2004. The energy of the fundamental harmonic of the cyclotron resonance absorption line near the maximum of the X-ray flux from the source (luminosity range 5…
Detection of the first thermonuclear X-ray burst from AX J1754.2-2754
Grebenev, S. A.; Chelovekov, I. V.
When analyzing the archival data of the INTEGRAL observatory, we detected an intense X-ray burst recorded on April 16, 2005, by the JEM-X and IBIS/ISGRI telescopes from the weak and poorly studied source AX J1754.2-2754. Analysis of its time profiles and spectra allows this event to be attributed to type I X-ray bursts associated with thermonuclea…
High-mass X-ray binaries and recent star formation history of the Small Magellanic Cloud
Gilfanov, M. R.; Shtykovskiy, P. E.
We study the relation between high-mass X-ray binary (HMXB) population and recent star formation history (SFH) for the Small Magellanic Cloud (SMC). Using archival optical SMC observations, we have approximated the color-magnitude diagrams of the stellar population by model stellar populations and, in this way, reconstructed the spatially resolved…
Fine structure of decametric type II radio bursts
Konovalenko, A. A.; Chernov, G. P.; Stanislavsky, A. A. +3 more
We have performed a comparative analysis of the fine structure of two decametric type II bursts observed on July 17 and August 16, 2002, with the 1024-channel spectrograph of the UTR-2 radio telescope in the frequency range 18.5 29.5 MHz and with the IZMIRAN spectrograph in the frequency range 25 270 MHz. The August 16 burst was weak, ∼2 5 s.f.u.,…
Young nuclei in dwarf elliptical galaxies
Prugniel, Ph.; Afanasiev, V. L.; Chilingarian, I. V. +1 more
We report the discovery of young embedded structures in three diffuse elliptical galaxies (dE) in the Virgo cluster: IC 783, IC 3468, and IC 3509. We performed 3D spectroscopic observations of these galaxies with the MPFS spectrograph at the 6-m Special Astrophysical Observatory telescope and obtained spatially resolved distributions of kinematic …