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11.
Klochkova V. G. Panchuk V. E. Tavolzhanskaya N. S. Yushkin M. V. 《Astronomy Letters》2020,46(8):528-540
Astronomy Letters - Evidence of wind variability and velocity stratification in the extended atmosphere has been found in the spectra of the supergiant V340 Ser ( $${=}$$ IRAS 17279 $$-$$ 1119)... 相似文献
12.
Radial velocities for 15 stars with high proper motions were measured as a result of spectral observations, conducted with the NES echelle spectrograph of the 6-m BTA telescope in the wavelength range of 3550–5100 Å with a spectral resolution of R=60000. The standard deviation of the measured velocity does not exceed σ ≤ 0.9 km/s for the stars with metallicity [Fe/H]? ?1, and σ ≤ 1.1 km/s for [Fe/H]? ?1. The heliocentric velocities measured with high accuracy in combination with trigonometrical parallaxes and proper motions from the HIPPARCOS catalog allowed us to determine the distances and parameters of the galactic orbits of the stars under study. In general they are located within 100 pc; the binarity of several program stars is confirmed. 相似文献
13.
V. G. Klochkova V. E. Panchuk M. V. Yushkin A. S. Miroshnichenko 《Astronomy Reports》2004,48(4):288-300
Our spectroscopic (with resolution R=75 000) and spectropolarimetric (R=15 000) observations with the 6-m telescope of the Special Astrophysical Observatory have enabled us to distinguish photospheric and circumstellar features in the optical spectrum of the bipolar protoplanetary nebula AFGL 2688 for the first time. The linear polarization of the radiation was measured at 5000–6600 Å. The emission in the lines of the sodium doublet and the Swan bands is formed in the envelope, and the mechanism exciting the transitions is resonance fluorescence. We conclude that the circumstellar envelope has a low density. Features of the structure of the nebula are discussed based on published high-angular-resolution photometric and polarimetric (HST NICMOS) data. 相似文献
14.
E. A. Barsukova N. V. Borisov A. N. Burenkov V. P. Goranskii V. G. Klochkova N. V. Metlova 《Astronomy Reports》2006,50(8):664-678
Our long-time monitoring of the B[e] star and transient X-ray source CI Cam during quiescence following the 1998 outburst demonstrates that the complex, stratified circumstellar envelope has tended to stabilize after this structure was perturbed by the passage of a shock wave from the outburst. The star’s U BV R brightness shows slow, possibly cyclic, variations with an amplitude of about 0.2m. We determined the spectral type of the primary, B4III-V, based on the widths of the absorption wings of high-numbered Balmer lines. A Doppler shift of 460 km/s was detected for the Hell λ4686 Å emission line. The shifts in this line yield an orbital period of 19.41 days, which is also manifested itself in the photometric data as a wave with a V amplitude of 0.034m. The orbit is elliptical, with an eccentricity of 0.62. It is most likely that the secondary is a white dwarf surrounded by an accretion disk. The primary’s mass exceeds 12 M ⊙ . The system may be at a late stage of its evolution, after the stage of mass exchange. 相似文献
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16.
V. G. Klochkova 《Astrophysical Bulletin》2014,69(3):279-295
We analyze the peculiarities of the optical spectra of luminous stars with circumstellar gas and dust envelopes: the time variability of the absorption-emission profiles of the Hα line, the presence of stationary emission and absorption molecular bands, multicomponent absorption-emission profiles of the Na I D doublet lines. We show that the peculiarities of the line profiles (the presence of an emission component in the Na I D doublet lines, the specific type of the molecular features, the asymmetry and splitting of the profiles of strong absorption features with low excitation potential of the low level) can be associated with the kinematic and chemical properties of the envelope and its morphological type. 相似文献
17.
Spectral monitoring of the yellow hypergiant ρ Cas with the by 6-m telescope of the Special Astrophysical Observatory with a spectral resolution of R ≥ 60 000 has led to the detection of new features in the kinematic state of its extended atmosphere following the ejection of matter in 2013. Significant changes in the profile of the Hα line were detected: the line had a doubled core for the first time in a 2014 spectrum, an inverse P Cygni profile on February 13, 2017, and the profile was again doubled on August 6, 2017 and September 5, 2017, but was strongly shifted toward longer wavelengths, indicating a rapid infall of matter. Splitting of the profiles of strong, low-excitation absorption lines into three components was first detected in 2017. There is no correlation between the evolution of the profiles of Hα and the splitted absorption lines. Pulsation-like variability with an amplitude of about 10 km/s is characteristic only of symmetric weak and moderate-intensity absorption lines. Shell emission lines of iron-group elements can be identified in the long-wavelength part of a spectrum obtained in 2013, whose intensity decreased until they completely disappeared in 2017. In the absence of emission in the cores of the H and K lines of Ca II, emission lines of shell metals are visible in the wings of these lines. 相似文献
18.
We report the results of modeling of the spectrum of the O3 If* Cyg OB2 No. 7 supergiant in a broad wavelength range. We determine the physical properties and chemical composition of its atmosphere not assuming the presence of local thermodynamic equilibrium. The atmosphere reveals an excess of nitrogen X(N)/X(N)⊙ = 3.2 and the carbon and oxygen deficiency X(C)/X(C)⊙ = 0.08, X(O)/X(O)⊙ = 0.09. The lines in the stellar spectrum are divided into three groups which fail to be describedwithin a single model. Themodels describing each of these groups differ by themass-loss rate and the law of wind velocity variation. Thus, the numerical modeling suggests that the wind of the supergiant is heterogeneous. In addition, this paper describes the features of the CMFGEN code used and investigates the sensitivity of its results to the variations of different parameters. 相似文献
19.
E. L. Chentsov V. G. Klochkova T. Kipper N. S. Tavolzhanskaya V. E. Panchuk M. V. Yushkin 《Astrophysical Bulletin》2011,66(4):466-477
We present an atlas of spectra of high signal-to-noise ratio and high spectral resolution (R ≥ 60000) in a poorly studied short-wavelength region up to 3055 Å. The spectra of well-studied stars of close temperatures (β Ori, α Lyr and α Cyg) are compared with the spectrum of a low-metallicity A-type supergiant KSPer, the atmosphere of which is poor in hydrogen, H/He = 3 × 10?5.We study the velocity field in the expanding atmospheres and envelopes of these stars. A complete atlas and detailed identification of spectral features are available in the Internet. 相似文献
20.
V. G. Klochkova 《Astrophysical Bulletin》2012,67(4):385-413
Since 1978, extensive observations of stars have been performed at the 6-m BTA telescope using both standard and newly developed instruments. We give a retrospective review of the results obtained within the framework of observational programs carried out at the 6-m telescope and aimed at the study of the physics and evolution of single and multiple stars of different masses. 相似文献