排序方式： 共有58条查询结果，搜索用时 15 毫秒
21.
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
22.
E. L. Chentsov V. G. Klochkova V. E. Panchuk M. V. Yushkin D. S. Nasonov 《Astronomy Reports》2013,57(7):527-547
The NES echelle spectrograph of the 6-m telescope of the Special Astrophysical Observatory has been used to obtain high-resolution spectra for 13 hot O3-B4 stars in the Cyg OB2 association, making it possible to study weak spectral features of stellar and interstellar origin. Velocity fields in the atmospheres and interstellar medium, characteristics of optical spectra and line profiles are investigated. The cascade star-formation scheme for the association is confirmed. Evidence is presented suggesting that the hypergiant Cyg OB2 No. 12 is an LBV object and that its anomalous reddening has a circumstellar nature. 相似文献
23.
High-resolution optical spectroscopy of the V2324 Cyg variable star associated with the IR source IRAS 20572+4919 is performed for the first time. More than 200 absorption features (mostly Fe II, Ti II, Cr II, Y II, Ba II, and Y II) are identified in the wavelength interval from 4549 to 7880 Å. The spectral type and rotation velocity of the star are found to be F0 III and V sin i = 69 km/s, respectively. Neutral-hydrogen and NaI D lines have complex P Cyg-type profiles. Neither systematic trend of radial velocity Vr with line depth Ro nor temporal variability of Vr have been found. We found that the value for the average heliocentric radial velocity is Vr = ?16.8 ± 0.6 km/s. The radial velocities inferred from the cores of the absorption components of the Hβ and NaI wind lines vary from ?140 to ?225 km/s (and the expansion velocities of the corresponding layers, from about 120 to 210 km/s). The maximum expansion velocity is found for the blue component of the split Hα absorption: 450 km/s for December 12, 1995. The method of model atmospheres is used to determine the following parameters of the star: effective temperature T eff = 7500 K, surface gravity log g = 2.0, microturbulence velocity ξ t = 6.0 km/s, and metallicity, which is equal to the solar value. The main peculiarity of the chemical composition of the star is the overabundance of lithium and sodium. The results cast some doubt on the classification of V2324 Cyg as a post-AGB star. 相似文献
24.
Results of the development and implementation of the Nasmyth Echelle Spectrograph (NES) of the 6-m telescope of the Special AstrophysicalObservatory are presented. The NES is a tunable spectral system with a large-diameter collimated beam that is suitable for various types of observations. Selected scientific programs carried out by the developers of the instrument are described as illustrations of its application. The possible development of the spectrograph with the 6-m telescope over the coming 19 years is discussed. 相似文献
25.
The main parameters of spectroscopic experiments in the UV range of the electromagnetic spectrum are estimated. Different spectral devices are compared in terms of their potential quality. Some technical details of current UV experiments and prospects of spectrographs of the WSO-UV project are discussed. 相似文献
26.
V. Klochkova T. Mishenina S. Korotin V. Marsakov V. Panchuk N. Tavolganskaya I. Usenko 《Astrophysics and Space Science》2011,335(1):141-147
Based on high quality spectral data (spectral resolution R≈60000) within the wavelength range of 3550–5000 Å we determined main parameters (effective temperature, surface gravity, microturbulent velocity, and content of chemical elements including heavy metals from Sr to Dy) for 14 metal-deficient G–K stars with large proper motions. The stars studied have a high range of metallicity: [Fe/H]=?0.3÷?2.9. Abundances of Mg, Al, Sr and Ba were calculated with non-LTE line-formation effects accounted for. The abundance both of radioactive element Th and the r-process element Eu were determined through synthetic spectrum calculations. We selected stars that belong to different galactic populations according to the kinematical criterion and parameters determined by us. We found that the studied stars with large proper motions refer to different components of the Galaxy: thin, thick disks and halo. The chemical composition of the star BD+80°?245 far from the galactic plane agrees with its belonging to the accreted halo. For the giant HD?115444 we obtained [Fe/H]=?2.91, an underabundance of Mn, an overabundance of heavy metals from Ba to Dy, and especially a high excess of the r-process element europium: [Eu/Fe]=+1.26. Contrary to its chemical composition typical for halo stars, HD?115444 belongs to the disc population according to its kinematic parameters. 相似文献
27.
We list the principal stages of astroclimatic studies concerned with choosing the sites for astrophysical observatories in
Caucasus and Crimea. We chow that the sites for three observatories in Northern Caucasus (Kislovodsk Mountain Astronomical
Station of Pulkovo Main Astronomical Observatory of the Russian Academy of Sciences, Special Astrophysical Observatory of
the Russian Academy of Sciences, Terskol Observatory) were chosen without obtaining representative statistical data in terms
of the number of clear night hours and seeing. We report the data on the number of clear night hours and seeing for the 6-m
telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences based on results of long-term observations.
We discuss the possible causes of the discrepancies between experimental and forecast data and conclude that currently none
of the three observatories in the North Caucasus can be preferred because of the great variety of the methods employed and
limited statistics in terms of astroclimatic and meteorological parameters for some sites. 相似文献
28.
V. G. Klochkova T. V. Mishenina V. E. Panchuk S. A. Korotin V. A. Marsakov I. A. Usenko V. V. Tsymbal 《Astrophysical Bulletin》2011,66(1):28-46
The results of spectroscopic observations made with the NES echelle spectrograph of the 6-m BTA telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences in the wavelength interval of 3550–5100 Å with a spectral resolution of R≥50000 are used to determine the fundamental parameters and atmospheric abundances of more than 20 chemical elements including heavy s- and r-process elements from Sr to Dy for a total of 14 metal-poor G-K-type stars. The abundances of Mg, Al, Sr, and Ba were calculated with non-LTE line-formation effects accounted for. The inferred overabundance of europium with respect to iron agrees with the results obtained for the stars of similar metallicity. The chemical composition of the star BD+80°245 located far from the Galactic plane is typical of stars of the accreted halo: this star exhibits, in addition to the over-deficiency of α-process elements, also the over-deficiency of the γ-process element Ba: [Ba/Fe]= ?1.46. The kinematical parameters and chemical composition imply that the stars studied belong to different Galactic populations. The abundance of the long-living element Th relative to that of the r-process element Eu is determined for six stars using the synthetic-spectrum method. 相似文献
29.
V. G. Klochkova V. E. Panchuk N. S. Tavolzhanskaya I. A. Usenko 《Astronomy Reports》2014,58(2):101-111
Multiple observations of the yellow hypergiant ρ Cas obtained in 2007–2011 in a wide wavelength range with spectroscopic resolving power R ≥ 60 000 have enabled studies of features of its optical spectrum in detail and brought to light previously unknown characteristics of the star’s extended atmosphere. The radial velocity measured from symmetric absorption lines of metals varies with an amplitude of about ±7 km/s around the systemic velocity V sys = ?47 km/s, due to low-amplitude pulsations of the atmospheric layers near the photosphere. At some times, a velocity gradient was observed in deep atmospheric layers of the star. A slight velocity stratification in the stellar atmosphere was detected for the first time, manifest as a difference of 3–4 km/s in the velocities measured from absorption lines of neutral metals and of ions. The long-wavelength components of split absorption lines of BaII, SrII, TiII, and other strong lines with low excitation potentials for their lower levels are distorted by nearby emission lines. It is suggested that the short-wavelength components, whose locations correspond to the narrow velocity range V r (blue) from approximately ?60 to ?70 km/s, are formed in a circumstellar envelope; one component of the D NaI doublet and the emission components of the FeII 6369.46 and 6432.68 Å ions are also formed there. 相似文献
30.
The Main Stellar Spectrograph (MSS) of the 6-m telescope of the Special Astrophysical Observatory was developed in the early 1970s and has been in permanent operation since 1975. This instrument has been successfully kept operational for a long time by equipping it with modern detectors and significantly upgrading its optical layout. In this paper we present the main parameters of the optomechanical layout of the MSS, the design features of auxiliary devices, operational experience and statistics of the use of the instrument with various detectors, and the characteristics of the corresponding observational techniques. 相似文献