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41.
The star BD-6°1178, which is identified with the IRAS 05238-0626 source, is shown for the first time to be a spectroscopic binary (SB2) by analyzing the high-resolution spectra taken with the NES echelle spectrograph of the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. The components of the binary have close spectral types and luminosity classes: F5 IV–III and F3V. The heliocentric radial velocities are measured for both components at four time moments in 2004–2005. The two stars have close rotation velocities, which are equal to 24 and 19 km/s. We do not confirm the classification of BD-6°1178 as a supergiant in the state of becoming a planetary nebula. BD-6°1178 probably is a young pre-MS stars. It is possibly a member of the 1c subgroup of the OriOB1 association. 相似文献
42.
V G Klochkova Gang Zhao V E Panchuk S V Ermakov National Astronomical Observatories Chinese Academy of Sciences Beijing Special Astrophysical Observatory Russian Academy of Sciences Nizhnij Arkhyz Karachai-Cherkessia Russia 《中国天文和天体物理学报》2004,4(3):279-283
We present an atlas of a group of bright stars in the range of spectral classes F-G and luminosity classes I-V. The spectra were obtained with spectral resolution R ～ 15 000 within spectral region 4500-6620/A Typical spectra of stars with different metallicity [Fe/H] are included. We also show the digital version of the spectral data in FITS format. 相似文献
43.
An atlas of high resolution (R = 60 000) CCD-spectra in the wavelength range 3500-5000A is presented for four objects in metallicity range -3.0 < [Fe/H] < -0.6, temperature range 4750 < Teff < 5900 K, and surface gravity range 1.6 < lgg < 5.0. We describe the calibration of the stellar atmospheric parameters using Alonso's formula based on the method of infrared flux and outline the determination of the abundances of a total number of 25 chemical elements. An analysis of the abundance determination errors for different chemical elements is carried out, and a method is provided for the observations and reduction of spectral material. Properties of the method of producing an atlas of spectra and line identifications are described. 相似文献
44.
Cross correlations between observed and synthetic spectra are used to discover yet another satellite of BM Ori with the following
characteristics: effective temperature Teff = 4000 K, radius R = 16R⊙, mass M = 1.8M⊙, spectral type K7 III, absolute bolometric stellar magnitude Mb = + 4m·0, axial rotation velocity V sini = 85 km/s, and relative luminosity 0.005 near the V band.
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Translated from Astrofizika, Vol. 49, No. 1, pp. 111–120 (February 2006). 相似文献
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47.
The basic parameters and detailed chemical compositions of three asymptotic giant branch stars with similar effective temperatures and surface gravities have been determined using CCD spectra obtained with the échelle spectrometers of the SAO 6-m telescope. The metallicity and chemical composition of the optical counterpart of the OH/IR star IRAS 18123 + 0511 have been derived for the first time. The abundance [X/H]⊙ of the iron group elements (V, Cr, Fe) is ?0.45 dex. An overabundance of oxygen, [O/Fe]⊙=1.44 dex, is detected in the atmosphere of this star. The abundances of s-process heavy elements are not enhanced, and are instead underabundant with respect to the metallicity: the average value of [X/Fe]⊙ for Y, Zr, Ba, La, Ce, Pr, Nd is ?0.25. The derived abundances confirm that IRAS 18123 + 0511 is in the AGB stage of its evolution. The metallicity of the object, together with its radial velocity V r=78.0 km/s and Galactic latitude |b|=11°, suggest that it belongs to the old disk population. The expansion velocity of the circumstellar envelope, V exp≈21 km/s, is derived from the positions of circumstellar absorption bands. The set of parameters obtained for the low-metallicity, highlatitude supergiants BD + 18° 2757 and BD + 18° 2890 (with iron abundances [Fe/H]⊙=2.10 and ?1.48, respectively) confirm that they are evolved halo stars, and probably UU Her-type stars. 相似文献
48.
Photometric variability and spectral features of the protoplanetary nebula LSII + 34° 26 = V1853 Cyg
V. P. Arkhipova N. P. Ikonnikova R. I. Noskova G. V. Komissarova V. G. Klochkova V. F. Esipov 《Astronomy Letters》2001,27(11):719-727
We present photoelectric and spectroscopic observations of the protoplanetary object V 1853 Cyg, a B supergiant with an IR excess. Over two years of its observations, the star exhibited rapid irregular light variations with amplitudes $\Delta V = 0\mathop .\limits^m 3$ , $\Delta B = 0\mathop .\limits^m 3$ , $\Delta U = 0\mathop .\limits^m 4$ and no correlation between color and magnitude. Its mean magnitude has not changed since the first UBV observations in 1973 (Drilling 1975). Low-resolution spectroscopic observations show that the spectrum of V 1853 Cyg in 2000 corresponded to that of a B1–B2 star with T eff ～ 20000 K. High-resolution spectroscopic observations confirm the conclusion that the profiles of absorption and emission lines are variable. We identified the star’s spectral lines and measured the equivalent widths of more than 40 lines. The star’s radial velocity is 〈V r 〉= ?49 × 5 km s?1, as measured from absorption lines, and ranges from–50 to–85 km s–1 for different lines, as measured from shell emission lines. The velocity of the dust clouds on the line of sight determined from diffuse interstellar bands (DIBs) and from interstellar Na I lines is 〈V r 〉= ?16 × 5 km s?1. The P Cyg profiles of the He I λ5876 Å and λ6678 Å lines suggest an ongoing mass loss by the star. An analysis of the observational data confirms the conclusion that the star belongs to the class of intermediatemass protoplanetary objects. 相似文献
49.
The abundances of helium and iron in the atmosphere of the principal star of the BM Ori system are estimated. Spectra obtained with the BTA telescope and from the archives of the IUE and HST satellites are used. It turns out that the helium abundance is close to that in the sun, while that of iron is lower. The helium and iron abundances in other stars of the Trapezium of Orion are generally similar to those in BM Ori, but there are some differences. For example, of the two stars 1 Ori C and 1Ori D, one has a higher and the other a lower abundance of helium than does the sun. At the same time, the secondary of BM Ori has a normal abundance of iron. 相似文献
50.
We have obtained the first high-spectral-resolution (R=15000 and 60000) optical spectra for the extremely luminous star No. 12, identified with the IR source IRAS 20308+4104 in the Cyg OB2 association. We have identified about 200 spectral features at 4552–7939 Å, including the interstellar NaI, KI lines and numerous DIBs, which are the strongest absorption lines in the spectrum, along with the HeI, CII, and SiII lines. A two-dimensional spectral classification indicates that the star's spectral type is B5±0.5 Ia+. Our analysis of the radial-velocity pattern shows the presence of a radial-velocity gradient in the stellar atmosphere, due to the infall of matter onto the star. The strong Hα emission line displays broad Thompson wings and time-variable core absorption, providing evidence that the stellar wind is inhomogeneous, and a slightly blue-shifted P Cygni absorption profile. We conclude that the wind is time-variable. 相似文献