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1.
A. A. Tatarnikova A. M. Tatarnikov E. A. Kolotilov V. I. Shenavrin G. V. Komissarova 《Astronomy Letters》2018,44(12):803-810
We present the results of our photometric UBV JHKL observations for the symbiotic star V1413 Aql obtained in 2012–2018. An analysis of the data has shown that inMay 2017 the system passed to a quiescent state with B ? V ≈ 0? 6 for the first time since 1993. It lasted no more than five months. The J ? K color at the primary minimum of 2012 reached 1? 5, which, given the interstellar reddening, corresponds to spectral type M5-M6 III of the cool component. A secondary minimum has been detected at φ ≈ 0.5 on the JK phase light curves constructed for the dates of observations with B ≥ 13. 相似文献
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Astronomy Reports - The results of many-year infrared observations of the Herbig AeBe star AB Aur at 1-5 μm (JHKLM bands) are presented. The duration of the photometric series, together with... 相似文献
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V. I. Shenavrin V. P. Grinin A. N. Rostopchina-Shakhovskaya T. V. Demidova D. N. Shakhovskoi S. P. Belan 《Astronomy Reports》2017,61(1):38-46
The results of ~15 years of photometric observations of the UX Ori star SV Cep in the near-infrared (JHKL) are presented. They demonstrate the presence of a cyclic component with a period of ~7 years in the variations of the IR fluxes. This is clearly seen in all four IR bands, but is absent in the optical. The variation amplitude is highest in the K band: ΔK ≈ 0.68 m . The shape of the variations differs slightly in the transition from J to L. However, it is reproduced with good accuracy during two cycles, suggesting a periodic process is observed. If the periodic perturbations in the circumstellar disk of SV Cep are due to a companion’s orbitalmotion, the orbital semi-major axis should be ~5AU, foramass of SVCep of 2.6M ⊙. The absence of a seven-year period in the optical light curve of SV Cep means that the observed period cannot be due to variations in the circumstellar extinction. The IR brightness variations could be due to the companion’s motion along an eccentric orbit, resulting in a periodic modulation of the rate of accretion onto the star. 相似文献
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A. A. Tatarnikova A. M. Tatarnikov V. F. Esipov T. N. Tarasova V. I. Shenavrin E. A. Kolotilov A. E. Nadzhip 《Astronomy Reports》2011,55(10):896-910
We present the results of our analysis of the spectrophotometric and photometric data for the symbiotic nova PU Vul acquired
in 2001–2008. The continuum in the optical observed in 2006–2008 cannot be reconciled with a standard model including light
from the cool component, hot component, and nebula. The hot component’s temperature increased to 194 000 K by 2008, while
its luminosity decreased by a factor of ten compared to the plateau of 1979–1991. The evolution of the hot component as reflected
by the Hertzsprung-Russell diagram does not agree with a theoretical model describing the evolution of a thermonuclear outburst
in a white-dwarf envelope. We estimate the mass of the hot component to be 0.5M
⊙ based on the luminosity of the hot component during the plateau stage. Our spectroscopy reveals periodic continuum-flux variations
due to brightness variability of the cool component, with an amplitude of at least 2
m
at 7000 ?. The spectral type of the cool component in 2008 was M6.3. 相似文献
6.
Anna Tatarnikova Marina Burlak Eugene Kolotilov Natalia Metlova Victor Shenavrin Sergei Shugarov Taisija Tarasova Andrey Tatarnikov 《天文和天体物理学研究(英文版)》2018,(8)
A new set of low-resolution spectral and UBVJHKL-photometric observations of the symbiotic nova PU Vul is presented. The binary has been evolving after its symbiotic nova outburst in 1977 and now it is in the nebular stage. It is found that the third orbital cycle(after 1977) was characterized by great changes in associated light curves. Now, PU Vul exhibits a sine-wave shape in all the light curves(with an amplitude in the U band of about 0.7 mag), which is typical for symbiotic stars in the quiescent state. Brightness variability due to pulsations of the cool component is now clearly visible in the VRI light curves. The amplitude of the pulsations increases from 0.5 mag in the V band to 0.8 mag in the I band. These two types of variability, as well as a very slow change in the physical parameters of the hot component due to evolution after the outburst of 1977, influence the spectral energy distribution(SED)of the system. The variability of emission lines is highly complex. Only hydrogen line fluxes vary with orbital phase. An important feature of the third orbital cycle is the first emergence of the OVI, 6828 Raman scattering line. We determine the temperature of the hot component by means of the Zanstra method applied to the He II, 4686 line. Our estimate is about 150 000 K for the spectrum obtained near orbital maximum in 2014. The VO spectral index derived near pulsation minimum corresponds to M6 spectral class for the cool component of PU Vul. 相似文献
7.
A. A. Fedoteva A. M. Tatarnikov B. S. Safonov V. I. Shenavrin G. V. Komissarova 《Astronomy Letters》2020,46(1):38-57
$$UBVJHKLM$$
photometry for the carbon Mira star V CrB are presented. The infrared observations were carried out in the time interval 1989–2018, while the $$U$$, $$B$$, and $$V$$ data were obtained in 2001–2014. The light and color curves are analyzed. The pulsation period of V CrB has been found to be $$355\overset{\textrm{d}}{.}2$$ in the infrared $$JHKLM$$ bands and $$352^{\textrm{d}}$$ for the optical $$BV$$ band. In the $$JHK$$ bands, apart from periodic pulsations, there are distinct sinusoidal variations in the average brightness level with a characteristic period of $${\sim}8300$$ days. Color–magnitude relationships have been revealed for the infrared and optical bands. The phase curves exhibit the wavelength dependence of the brightness variability amplitude. The light curves for various bands and colors are discussed. We have constructed the model of a spherically symmetric circumstellar dust envelope that allows the observed spectral energy distribution at both maximum and minimum light to be reproduced equally well (within the model assumptions) and is consistent with the observations of V CrB by differential speckle polarimetry. The model is characterized by the following parameters: the optical depth is $$\tau_{K}=0.33$$, the inner and outer radii of the envelope are 8 and 40 000 AU, respectively. The envelope contains spherical carbon dust grains ($$3/4$$ by mass) and silicon carbide dust grains. Dust grains with a radius of 0.5 $$\mu$$m account for $$90\%$$ of the envelope mass. The remaining $$10\%$$ of the mass is accounted for by finer dust with a grain radius of 0.1 $$\mu$$m. Based on the observational data, we have estimated the bolometric flux from V CrB: $$2.6\times 10^{-7}$$ and $$5.1\times 10^{-7}$$ erg cm$${}^{-2}$$ s$${}^{-1}$$ at minimum and maximum light, respectively. The effective temperature of the star is $$T_{\textrm{max}}=3000$$ K at maximum light and $$T_{\textrm{min}}=2400$$ K at minimum light. 相似文献
8.
Arkhipova V. P. Burlak M. A. Ikonnikova N. P. Komissarova G. V. Esipov V. F. Shenavrin V. I. 《Astronomy Letters》2020,46(2):100-119
Astronomy Letters - We present the results of a new epoch (2009–2019) of a long-term (50 years) photometric monitoring of the variable planetary nebula IC 4997 (QV Sge). The integral (star +... 相似文献
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