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V.?A.?Hagen-ThornEmail author V.?M.?Larionov A.?A.?Arkharov E.?I.?Hagen-Thorn D.?A.?Blinov D.?A.?Morozova Yu.?V.?Troitskaya L.?O.?Takalo A.?Sillanpy?? 《Astronomy Reports》2015,59(6):551-562
The results of multi-color photometric and polarization observations of the blazar S4 0954+658 carried out mainly in the Astronomical Institute of St. Petersburg State University and the Central Astronomical Observatory of the Russian Academy of Sciences in 2008–2012 are analyzed. Individual variable components that are responsible for the activity are distinguished; the power-law spectrum and high degree of polarization confirm that the emission is synchrotron radiation. Modeling the observed dependences between the parameters of the polarization and intensity is used to derive parameters of both the constant and the variable components of the radiation. The observed color variability (“the brighter, the bluer”) can be explained by the superposition of a red constant component and a bluer variable component with a constant relative spectral energy distribution. 相似文献
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V. A. Hagen-Thorn V. M. Larionov D. A. Morozova A. A. Arkharov E. I. Hagen-Thorn E. S. Shablovinskaya M. S. Prokop’eva V. A. Yakovleva 《Astronomy Reports》2018,62(2):103-115
The results of optical, radio, and gamma-ray observations of the blazar AO 0235+16 are presented, including photometric (BV RIJHK) and polarimetric (R)monitoring carried out at St. Petersburg State University and the Central (Pulkovo) Astronomical Observatory in 2007–2015, 43 GHz Very Long Baseline Interferometry radio observations processed at Boston University, and a gamma-ray light curve based on observationswith the Fermi space observatory are presented. Two strong outbursts were detected. The relative spectral energy distributions of the variable components responsible for the outbursts are determined; these follow power laws, but with different spectral indices. The degree of polarization was high in both outbursts; only an average relationship between the brightness and polarization can be found. There was no time lag between the variations in the optical and gamma-ray, suggesting that the sources of the radiation in the optical and gamma-ray are located in the same region of the jet. 相似文献
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G. M. Karataeva N. A. Tikhonov O. A. Galazutdinova V. A. Hagen-Thorn 《Astronomy Letters》2006,32(4):236-243
We present the results of stellar photometry in eight fields of NGC 5128 (Cen A), a candidate polar-ring galaxy, obtained by reducing images from the Hubble Space Telescope archive. In all cases, the color-magnitude diagrams reached the red-giant region, and the distance to the galaxy was determined from the position of the tip of the red-giant branch (4.1 Mpc), in agreement with previous estimates. Comparison of the diagrams with theoretical isochrones indicates that the red supergiants in the dark lane region are metal-rich, which is atypical of the polar rings. Our results are consistent with the assumption made by several authors that the absorption of a less massive spiral galaxy by a more massive one is observed in NGC 5128. 相似文献
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V. A. Hagen-Thorn V. M. Larionov E. G. Larionova N. A. Kudryavtseva A. V. Tikhonov A. V. Hagen-Thorn A. A. Arkharov A. Di Paola F. D'Alessio 《Astronomy Letters》2004,30(4):209-217
We present the results of our multicolor observations of BL Lac in the period 1999–2001. We show that the spectral energy distribution of the variable component in the range from K to B had remained unchanged for three years. The power-law spectrum is indicative of its synchrotron nature. 相似文献
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We report the results of spectroscopic and photometric observations of ZGC 2315+03 with the 6-m Special Astrophysical Observatory telescope. This object is shown to belong neither to polar ring galaxies nor to close interacting pairs. The peculiar appearance of ZGC 2315+03 is explained by projection effects. 相似文献
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V. A. Hagen-Thorn A. V. Hagen-Thorn S. G. Marchenko O. V. Mikolaichuk 《Astrophysics》2000,43(2):129-135
The color variability of BL Lac during the strong 1997 outburst was studied. It was found that the energy distribution in
the spectrum of the variable source, which determines the object’s photometric behavior, did not vary during the outburst.
It was a power- law spectrum and was flatter than during other, lower-power out-bursts. There is no doubt of the synchrotron
nature of the variable source.
Translated from Astrofizika, Vol. 43, No. 2, pp. 175-182, April–June, 2000. 相似文献
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Results are shown for photoelectric B and V observations of Markarian 421 (Mrk 421) from 1982 to 1991. It is found that one can explain the dependence of the color indices (B-V) averaged for a season on the B magnitude within a two-component model (an underlying galaxy + a variable point source). It is determined that the color index (B-V)
var
of the variable source does not change, and the observed variability of the color index is caused by variation of the contribution from the variable source to the total flux.Translated from Astrofizika, Vol. 37, No. 2, pp. 285–300, April–June, 1994.V. A. Hagen-Thorn and V. A. Yakovleva are grateful to the American Astronomical Society for financial support in 1993. 相似文献
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V. A. Hagen-Thorn V. M. Larionov C. M. Raiteri E. I. Hagen-Thorn A. V. Shapiro A. A. Arkharov L. O. Takalo A. Sillanpää 《Astronomy Reports》2007,51(11):882-890
Multicolor (UBVRIJHK) observation of the blazar AO 0235+16 are analyzed. The light curves were compiled at the Turin Observatory from literature
data and the results of observations obtained in the framework of the WEBT program (). The color variability of the blazar was studied in eight time intervals with a sufficient number of multicolor optical
observations; J H K data are available for only one of these. The spectral energy distribution (SED) of the variable component remained constant within each interval, but varied strongly from one interval to another. After correction for
dust absorption, the SED can be represented by a power law in all cases, providing evidence for a synchrotron nature of the
variable component. We show that the variability at both optical and IR wavelengths is associated with the same variable source. 相似文献