Spectral and photometric monitoring of distant core-collapse supernovae in the SAO RAS     

A. S. Moskvitin  T. A. Fatkhullin  V. V. Sokolov  V. N. Komarova  A. J. Drake  R. Roy  D. Yu. Tsvetkov 《Astrophysical Bulletin》2010,65(3):230-237

This paper describes the aims, objectives and first results of the observational program for the study of distant core-collapse supernovae (SNe) with redshifts z ≲ 0.3. This work is done within the framework of an international cooperation program on the SNe monitoring at the 6-m BTA telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, and other telescopes. We study both the early phases of events (SN type determination, redshift estimation, and a search for manifestations of a wind envelope), and the nebular phase (the effects of explosion asymmetry). The SNe, associated with cosmic gamma-ray bursts are of particular interest. An interpretation of our observational data along with the data obtained on other telescopes is used to test the existing theoretical models of both the SN explosion, and the surrounding circumstellar medium. In 2009 we observed 30 objects; the spectra were obtained for 12 of them. We determined the types, phases after maximum, and redshifts for five SNe (SN 2009db, SN 2009dy, SN 2009dw, SN 2009ew, SN 2009ji). Based on the obtained photometric data a discovery of two more SNe was confirmed (SN 2009bx and SN 2009cb). A study of two type II supernovae in the nebular phase (SN 2008gz and SN 2008in) is finalized, four more objects (SN 2008iy, SN 2009ay, SN 2009bw, SN 2009de) are currently monitored.  相似文献   

Near-Earth space as an object of global monitoring     

I. V. Barmin  V. P. Kulagin  V. P. Savinykh  V. Ya. Tsvetkov 《Solar System Research》2014,48(7):531-535

Near-Earth space is analyzed as a specific object for global monitoring. The structure and specific features of near-Earth space are considered. It is shown that this zone includes almost all the terrestrial fields and the regions where space is actively explored by man.  相似文献   

Stochastic models of hot planetary and satellite coronas: Total water loss in the Martian atmosphere     

V. I. Shematovich  G. A. Tsvetkov  M. A. Krestyanikova  M. Ya. Marov 《Solar System Research》2007,41(2):103-108

Estimates of the total thermal and nonthermal losses of hydrogen and the total nonthermal loss of oxygen from the atmosphere of Mars are discussed, and their ratio is analyzed. It is shown that an H to O ratio of 2:1 has not been achieved in any of the current models of various authors. The closest ratio, H:O = 4:1, has been obtained by Krestyanikova and Shematovich (2006) in the model of formation of a hot oxygen corona.  相似文献   

Distribution of type Ib/c supernovae relative to galactic spiral arms     

G. A. Mikhailova  O. S. Bartunov  D. Yu. Tsvetkov 《Astronomy Letters》2007,33(11):715-719

Type Ib/c supernovae are shown to be concentrated to the inner edges of the spiral arms, with the distributions for type Ib and Ic supernovae being identical. We have found differences between the distributions of type II and Ib/c supernovae relative to spiral arms, suggesting that the type Ib/c presupernovae are, on average, younger.  相似文献   

Observations of five supernovas: 1985–1986     

D. Yu. Tsvetkov 《Astrophysics》1988,29(2):565-572

P. K. Shternberg State Astronomical Institute. Translated from Astrofizika, Vol. 29, No. 2, pp. 260–270, September–October, 1988.  相似文献   

Light curves of the type II supernovas 1980D and 1985L     

G. N. Kimeridze  D. Yu. Tsvetkov 《Astrophysics》1989,31(1):423-428

Abastumani Astrophysical Observatory: P. K. Shternberg State Astronomical Institute. Translated from Astrofizika, Vol. 31, No. 1, pp. 17–24, July–August, 1989.  相似文献   

A new model of the zonal structure of fractures     

A. A. Spivak  V. M. Tsvetkov 《Doklady Earth Sciences》2009,424(1):151-154

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Inaccuracies in the spectral classification of stars from the Tycho-2 Spectral Type Catalogue     

A. S. Tsvetkov  A. V. Popov  A. A. Smirnov 《Astronomy Letters》2008,34(1):17-27

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 differ significantly. It is these stars that are the subject of our study. We have been able to find the causes of these differences.  相似文献   

Experimental errors of measurements of vertical geomagnetic gradients in the stratosphere     

Yu. P. Tsvetkov  O. M. Brekhov  S. V. Filippov  T. N. Bondar  A. A. Ivanov  A. V. Krapivnyi  N. S. Nikolaev 《Geomagnetism and Aeronomy》2007,47(4):510-514

The errors of measurements of vertical geomagnetic gradients at altitudes of 20–40 km, using a balloon magnetic gradiometer with a 6-km-long measuring base oriented along gravity, have been studied in the work. The errors related to the deviation of the measuring base position relative to the vertical have been studied during the real balloon flight with the help of the navigation GPS receivers. The deviations of the measuring base within 5°, which can sometimes reach 15°, have been obtained. This results in a decrease in the magnetic gradient measurement accuracy due to the errors introduced in the specification of the normal magnetic field used to detect magnetic anomalies. To eliminate this error, a GPS receiver was built in each magnetometer in order to observe magnetometers during synchronous measurements and to correct the measurements for the normal magnetic field. It has been indicated that the effect of deviations of the measuring base position on the results is not more than 2% of the measured value at such organization of a gradiometer.  相似文献   

Blue edges of the Delta-Scuti instability strip: Theory in comparison with observations     

Ts. G. Tsvetkov 《Astrophysics and Space Science》1983,89(2):435-445

Models of Delta Scuti stars are tested against radial pulsations in the four lowest modes, using a linear, nonadiabatic approximation. It is shown that the theoretical blue edge locations of the instability strip on the H-R diagram depend strongly (ΔlogT _e?0.03) on both opacity interpolation and variations of the envelope helium abundanceY. Several other factors have small effect (Δ logT _e?0.01): variations of the heavy element abundanceZ, the use of various opacity tables, the treatment of convection, and the number of envelope mass zones. A comparison with both results obtained by various authors and observations is performed. The locations of the observed blue edge and our theoretical third-harmonic ones are consistent. A nonlinear dependence of the theoretical blue edge locations on envelope helium abundanceY is derived. A star withY?0.2 may pulsate within the instability strip, if it is not near the blue edge.  相似文献