Turbulence in the inner solar wind determined from frequency fluctuations of the downlink signals from the ULYSSES and GALILEO spacecraft     

A. I. Efimov  I. V. Chashei  M. K. Bird  L. N. Samoznaev  D. Plettemeier 《Astronomy Reports》2005,49(6):485-494

The results of several sets of measurements of the frequency of radio signals during coronal-sounding experiments carried out from 1991 to 2000 using the ULYSSES and GALILEO spacecraft are presented and analyzed. The S-band signals (carrier frequency f = 2295 MHz) were received at the three 70-m widely spaced ground stations of the NASA Deep Space Network. As a rule, the frequency-fluctuation spectra at frequencies above 1 mHz are power-laws. At small heliocentric distances, R < 10R_⊙ (R_⊙ is the solar radius), the spectral index is close to zero; this corresponds to a spectral index for the one-dimensional turbulence spectrum p₁ = 1. The index of the frequency-fluctuation spectra in the region of the supersonic solar wind at distances R > 30 R_⊙ is between 0.5 and 0.7 (p₁ = 1.5–1.7). The results demonstrate a substantial difference between the turbulence regimes in these regions: in the region of the established solar wind, the power-law spectra are determined by nonlinear cascade processes that pump energy from the outer turbulence scale to the small-scale part of the spectrum, whereas such cascade processes are absent in the solar wind acceleration region. Near the solar minimum, the change in the turbulence regime of the fast, high-latitude solar wind occurs at greater distances than for the slow, low-latitude solar wind. Spectra with a sharp cutoff at high frequencies have been detected for the first time. Such spectra are observed only at R < 10 R_⊙ and at sufficiently low levels of the electron density fluctuations. The measured cutoff frequencies are between 10 and 30 mHz; the cutoff frequency tends to increase with heliocentric distance. The variance of the plasma-density fluctuations has been estimated for the slow, low-latitude solar wind. These estimates suggest that the relative fluctuation level at distances 7 R_⊙ < R < 30 R_⊙ does not depend on heliocentric distance. The cross correlation of the frequency fluctuations recorded at widely spaced ground stations increases with the index of the frequency-fluctuation spectrum. At distances R ≈ 10 R_⊙, the rate of temporal changes in irregularities on the scale of several thousand kilometers is less than or comparable to the solar wind velocity.  相似文献   

First experimental studies of a perturbed zone preceding the front of a coronal mass ejection     

M. V. Eselevich  V. G. Eselevich 《Astronomy Reports》2007,51(11):947-954

The first experimental evidence for a perturbed zone that is likely filled with fast magnetoacoustic oscillations and precedes a coronal mass ejection is presented. When the speed of the coronal mass ejection exceeds the Alfven speed, an outward-moving discontinuity of the plasma density is observed in front of the perturbed zone, on scales comparable to the mean-free path for proton-proton collisions. This suggests that this discontinuity should be interpreted as a collisional shock at distances of R < 30 R _⊙ (where R _⊙ is the solar radius).  相似文献   

Radial pulsations of helium stars and a model for BX CIR     

Yu. A. Fadeev  M. F. Novikova 《Astronomy Reports》2003,47(1):68-74

The results of hydrodynamical calculations of radially pulsating helium stars with masses 0.5M_⊙≤M≤0.9M_⊙, bolometric luminosities 600L_⊙≤5×10³L_⊙, and effective temperatures 1.5×10⁴ K≤T_eff≤3.5×10⁴ K are presented. The pulsation instability of these stars is due to the effects of ionization of iron-group elements in layers with temperatures T～2×10⁵ K. The calculations were carried out using opacities for the relative mass abundances of hydrogen and heavy elements X=0 and Z=0.01, 0.015, and 0.02. Approximate formulas for the pulsation constant Q over the entire range of pulsation instability of the hot helium stars in terms of the mass M, radius R, effective temperature T_eff, and heavy-element abundance Z are derived. The instability of BX Cir to radial pulsations with the observed period Π=0.1066 d occurs only for a mass M≥0.55M_⊙, effective temperature T_eff≥23000 K, and heavy-element abundance Z≥0.015. The allowed mass of BX Cir is in the range 0.55M_⊙≤M≤0.8M_⊙, which corresponds to luminosities 800L_⊙≤M≤1400L_⊙ and mean radii 1.7R_⊙?R?2.1R_⊙.  相似文献   

Thermodynamic Properties of Natural Cuspidine     

L. P. Ogorodova  M. F. Vigasina  O. V. Kononov  N. N. Koshlyakova  D. A. Ksenofontov  D. A. Khanin  V. D. Shcherbakov  L. V. Mel’chakova 《Geochemistry International》2018,56(8):865-869

The paper reports pioneering data on the calorimetrically determined enthalpy of formation from elements of cuspidine, Ca fluordiorthosilicate Ca₄Si₂O₇F₂, from the Tyrny-Auz Mo–W deposit in Kabardino- Balkaria, Russia. The data were obtained by high-temperature melt solution calorimetry. The determined value is ΔfH_el° (298.15 K) =–5190 ± 13 kJ/mol. The paper reports estimated S°(298.15 K) and Δ_fG_el° (298.15 K) of cuspidine.  相似文献   

Abundances of carbon,nitrogen, oxygen,and other elements in the atmospheres of the giants 25 Mon and HR 7389     

T. M. Rachkovskaya 《Astronomy Reports》2005,49(9):714-723

An analysis of high-resolution CCD spectra of the giant 25 Mon, which shows signs of metallicity, and the normal giant HR 7389 is presented. The derived effective temperatures, gravitational accelerations, and microturbulence velocities are T_eff = 6700 K, log g = 3.24, and ξ _t = 3.1 km/s for 25 Mon and T_eff = 6630 K, log g = 3.71, and ξ _t = 2.6 km/s for HR 7389. The abundances (log ε) of nine elements are determined: carbon, nitrogen, oxygen, sodium, silicon, calcium, iron, nickel, and barium. The derived excess carbon abundances are 0.23 dex for 25 Mon and 0.16 dex for HR 7389. 25 Mon displays a modest (0.08 dex) oxygen excess, with the oxygen excess for HR 7389 being somewhat higher (0.15 dex). The nitrogen abundance is probably no lower than the solar value for both stars. The abundances of iron, sodium, calcium (for HR 7389), barium, and nickel exceed the solar values by 0.22–0.40 dex for both stars. The highest excess (0.62 dex) is exhibited by the calcium abundance for 25 Mon. Silicon displays a nearly solar abundance in both stars—small deficits of ?0.03 dex and ?0.07 dex for 25 Mon and HR 7389, respectively. No fundamental differences in the elemental abundances were found in the atmospheres of 25 Mon and HR 7389. Based on their T_eff and log g values, as well as theoretical calculations, A. Claret estimated the masses, radii, luminosities, and ages of 25 Mon (M/M_⊙ = 2.45, log(R/R_⊙) = 0.79, log(L/L_⊙) = 1.85, t = 5.3 × 10⁸ yr) and HR 7389 (M/M_⊙ = 2.36, log(R/R_⊙) = 0.50, log(L/L_⊙) = 1.24, t = 4.6 × 10⁸ yr), and also of the stars 20 Peg (M/M_⊙ = 2.36, log(R/R_⊙) = 0.73, log(L/L_⊙) = 1.79, t = 4.9 × 10⁸ yr) and 30 LMi (M/M_⊙ = 2.47, log(R/R_⊙) = 0.73, log(L/L_⊙) = 1.88, t = 4.8 × 10⁸ yr) studied by the author earlier.  相似文献   

Calorimetric Study of Natural Basic Copper Phosphate—Pseudomalachite     

L. P. Ogorodova  L. V. Melchakova  M. F. Vigasina  Yu. D. Gritsenko  D. A. Ksenofontov 《Geochemistry International》2018,56(5):484-487

The thermochemical study of a natural basic copper phosphate, pseudomalachite Cu₅(PO₄)₂(OH)₄ (Virneberg deposit, Germany), was carried out using high-temperature melt solution calorimetry method with a Tian–Calvet microcalorimeter. The enthalpy of formation of the mineral from elements was obtained to be Δ _f H_el(298.15 K) =–3214 ± 13 kJ/mol. The value of the Gibbs energy of pseudomalachite formation calculated using literature data on its standard entropy is Δ _f H_el^°(298.15 K) =–2812 ± 13 kJ/mol.  相似文献   

Photometry and spectroscopy of the system V4641 sagittarii in quiescence     

V. P. Goranskij  E. A. Barsukova  A. N. Burenkov 《Astronomy Reports》2003,47(9):740-749

We present the results of our CCD photometric and moderate-dispersion spectroscopic observations of the binary system V4641 Sgr, which contains a black hole of mass ≈9.5M_⊙ and a normal B9III star. The photometric light curve reveals an ellipticity effect with very high amplitudes in V and R, 0.40^m and 0.37^m, and the color curve shows that the surface temperature is nonuniform. All this testifies to tidal distortion of the normal star's surface due to the massive companion and to a high inclination of the orbit to the line of sight. In June and July 2002, during quiescence, we obtained data during three flares with amplitudes up to 0.26^m. In particular, spectroscopic observations were acquired near the time of the black hole's inferior conjunction. One hour before conjunction, a depression by EW=0.5 Å was observed in the red wing of the Hα absorption line, interpreted as absorption by gas flowing in the direction from the observer toward the normal star. This flow is apparently associated with a rarefied gas disk around the black hole, and the conjunction grazes the stellar surface if the orbital inclination is close to 70.7°. The maximum velocity along a circular Keplerian orbit is 650 km/s at a distance of R=0.15–0.20a from the black hole (where a is the component separation). Thus, we find the mass of the black hole to be M _BH =7.1–9.5M_⊙, confirming the model of Orosz et al. (2001).  相似文献   

The impact of reflection effects on the parameters of the old pre-cataclysmic variables MS Peg and LM Com     

V. V. Shimansky  N. V. Borisov  N. N. Shimanskaya 《Astronomy Reports》2003,47(9):763-776

We have determined the main parameters of the old precataclysmic variable stars MS Peg and LM Com. The radial velocities of the components, reflection effects in the spectra, and light curves of the systems are studied based on model stellar atmospheres subject to external irradiation. Forty-seven moderate-resolution spectra for MS Peg and 57 for LM Com obtained with the 6-m telescope of the Special Astrophysical Observatory are used to derive the refined orbital periods of 0.1736660 days and 0.2586873 days, respectively; the orbital eccentricities do not exceed e=0.04. The mass (M _w =0.49e_⊙) and radius (e _w =0.015R_⊙) of the MS Peg primary calculated using the gravitational redshift correspond to those for a cooling carbon white dwarf with a thin hydrogen envelope. The parameters of the red dwarf (M _r =0.19M_⊙, T_eff=3560 K, R _r =0.18R_⊙) are close to those derived from evolutionary tracks for main-sequence M stars with solar chemical composition. The radius (R _r =0.22R_⊙) and temperature (T_eff=3650 K) of the LM Com secondary exceed theoretical estimates for main-sequence stars with masses of M _r =0.17M_⊙. The luminosity excess of the red dwarf in LM Com can be explained by a prolonged (T>5×10⁶ yrs) relaxation of the M star to its normal state after the binary leaves the common-envelope stage. For both systems, theoretical U, B, V, and R light curves and spectra calculated using the adopted sets of parameters are generally consistent with the observations. This confirms the radiative origin of the hot spots, the unimportance of horizontal radiative transport, and the absence of large-scale velocity fields with high values (V_trans>50 km/s) at the surfaces of the secondaries. Most of the emission lines in the spectra of these objects are formed under conditions close to thermalization, enabling modeling of their pro files in an LTE approximation. A strong λ3905 Å emission line has been identified as the 3s²3p4s 1P⁰-3s²3p² 1S SiI λ3905.52 Å line formed in the atmosphere of the hot spot. The observed intensity can be explained by non-LTE “superionization” of SiI atoms by soft UV radiation from the white dwarf. We suggest a technique for identifying binaries whose cool components are subject to UV irradiation based on observations of λ3905 Å emission in their spectra.  相似文献   

Effect of 2-D Random Field Discretization on Failure Probability and Failure Mechanism in Probabilistic Slope Stability     

Liang Li  Xuesong Chu 《Geotechnical and Geological Engineering》2016,34(2):437-447

This paper investigates, using the random field theory and Monte Carlo simulation, the effects of random field discretization on failure probability, p _f, and failure mechanism of cohesive soil slope stability. The spatial sizes of the discretized elements in random field Δx, Δy in horizontal and vertical directions, respectively, are assigned a series of combinational values in order to model the discretization accuracy. The p _f of deterministic critical slip surface (DCSS) and that of the slope system both are analyzed. The numerical simulation results have demonstrated that both the ratios of Δy/λ _y (λ _y  = scale of fluctuation in vertical direction) and Δx/λ _x (λ _x  = scale of fluctuation in horizontal direction) contribute in a similar manner to the accuracy of p _f of DCSS. The effect of random field discretization on the p _f can be negligible if both the ratios of Δx/λ _x and Δy/λ _y are no greater than 0.1. The normalized discrepancy tends to increase at a linear rate with Δy/λ _y when Δx/λ _x is larger than 0.1, and vice versa for p _f of DCSS. The random field discretization tends to have more considerable influence on the p _f of DCSS than on that of the slope system. The variation of p _f versus λ _x and λ _y may exhibit opposite trends for the cases where the limit state functions of slope failure are defined on DCSS and on the slope system as well. Finally, the p _f of slope system converges in a more rapid manner to that of DCSS than the failure mechanism does to DCSS as the spatial variability of soil property grows from significant to negligible.  相似文献   

The mass of the compact object in the X-ray binary her X-1/HZ her     

M. K. Abubekerov  E. A. Antokhina  A. M. Cherepashchuk  V. V. Shimanskii 《Astronomy Reports》2008,52(5):379-389

We have obtained the first estimates of the masses of the components of the Her X-1/HZ Her X-ray binary system taking into account non-LTE effects in the formation of the H _γ absorption line: m _x = 1.8 M _⊙ and m _v = 2.5 M _⊙. These mass estimates were made in a Roche model based on the observed radial-velocity curve of the optical star, HZ Her. The masses for the X-ray pulsar and optical star obtained for an LTE model lie are m _x = 0.85 ± 0.15 M _⊙ and m _v = 1.87 ± 0.13 M _⊙. These mass estimates for the components of Her X-1/HZ Her derived from the radial-velocity curve should be considered tentative. Further mass estimates from high-precision observations of the orbital variability of the absorption profiles in a non-LTE model for the atmosphere of the optical component should be made.  相似文献   

Additional plasma streams with steep fronts in structures of enhanced brightness in the coronal streamer belt     

M. V. Eselevich  V. G. Eselevich 《Astronomy Reports》2004,48(8):688-698

The presence of additional plasma streams with enhanced density in bright rays of the solar coronal-streamer belt is demonstrated. The streams have steep fronts, whose widths δ≈0.10R_⊙ (where R_⊙ is the solar radius) are comparable to the spatial resolution of the LASCO C3 instrument of the SOHO satellite. The additional streams are similar to streams of the slow, quasi-steady solar wind in the streamer belt in terms of their plasma density, directional velocity, and lifetime and are apparently one of the main sources of the slow solar wind.  相似文献   

The formation of a perturbed zone and shock wave excited by a coronal mass ejection     

M. V. Eselevich  V. G. Eselevich 《Astronomy Reports》2009,53(2):173-185

The existence of perturbed zones ahead of coronal mass ejections (CMEs) has been confirmed, and their evolution with increasing CME velocity studied. At CME velocities that are close to or higher than the local Alfvén velocity, a discontinuity forms in the plasma density distribution ahead of the perturbed zone, which can be interpreted as a shock. Estimates testify that, at distances from the solar center of R < (15–20) R _⊙, the width of the observed shock front is probably of the order of the mean free path for proton-proton collisions.  相似文献   

Determination of the thermodynamic properties of compounds in the Ag-Au-Se and Ag-Au-Te systems by the EMF method     

E. A. Echmaeva  E. G. Osadchii 《Geology of Ore Deposits》2009,51(3):247-258

The standard thermodynamic properties (Δ_f G°, S°, Δ_f H°) of the following synthetic minerals and compounds in the Ag-Au-Se and Ag-Au-Te systems were determined by the EMF method: β-Ag₂Se (low-temperature naumannite), α-Ag₂Se (high-temperature naumannite), Ag₃AuSe₂ (fischesserite), AuSe, Ag₅Te₃ (stützite), Ag₂ Te (hessite), and Ag₃AuTe₂ (petzite). All minerals and compounds were produced by solid-phase synthesis from elements or electrum of the given composition in evacuated ampoules made of quartz glass. The phases were verified by X-ray diffraction analysis, microscopically in reflected light, and with an electron microprobe. The absence of the ternary compound AgAuSe in the Ag-Au-Se system was confirmed by solid-phase annealing. On the basis of experimental data on the electromotive force E versus temperature, the equations E(T) were calculated, from which the temperature-dependent relationships of the Gibbs energy in the relevant reactions and the standard thermodynamic functions of compounds within the range 300–502 K were obtained.  相似文献   

Dependence of the absorption-line profiles and radial-velocity curve of the optical star in an X-ray binary on the orbital inclination and component-mass ratio     

M. K. Abubekerov  É. A. Antokhina  A. M. Cherepashchuk 《Astronomy Reports》2005,49(10):801-813

Theoretical absorption-line profiles and radial-velocity curves for tidally deformed optical stars in X-ray binary systems are calculated assuming LTE. The variations in the profile shapes and radial-velocity curve of the optical star are analyzed as a function of the orbital inclination of the X-ray binary system. The dependence of the shape of the radial-velocity curve on the orbital inclination i increases with decreasing component-mass ratio q = m _x /m _v . The integrated line profiles and radial-velocity curves of the optical star are calculated for the Cyg X-1 binary, which are then used to estimate the orbital inclination and mass of the relativistic object: i < 43° andm _x = 8.2–12.8 M_⊙. These estimates are in good agreement with earlier results of fitting the radial-velocity curve of Cyg X-1 using a simpler model (i < 45°, m _x = 9.0–13.2 M_⊙).  相似文献   

Application of time- and magnitude-predictable model for long-term earthquake prediction in Iran   总被引：1，自引：0，他引：1  

H. Zafarani  S. M. M. Ghafoori  M. R. Adlparvar  P. Rajaeian  A. Hasankhani 《Natural Hazards》2015,78(1):155-178

The regional time- and magnitude-predictable model has been applied successfully in diverse regions of the world to describe the occurrence of main shocks. In the current study, the model has been calibrated against the historical and instrumental catalog of Iranian earthquakes. The Iranian plateau is divided into 15 seismogenic provinces; then, the interevent times for strong main shocks have been determined for each one. The empirical relations reported by Papazachos et al. (Tectonophysics 271:295–323, 1997a) for the Alpine–Himalayan belt (including Iran) were adopted except for the constant terms that were calculated separately for every seismotectonic area. By using the calibrated equations developed for the study area and taking into account the occurrence time and magnitude of the last main shocks in each seismogenic source, the time-dependent conditional probabilities of occurrence P(?t) of the next main shocks during next 10, 20, 30, 40 and 50 years as well as the magnitude of the expected main shocks (M _f) have been estimated. The immediate probability (within next 10 years) of a large main shock is estimated to be high and moderate (>35 %) in all regions except zones 9 (M _f = 5.8) and 15 (M _f = 6.1). However, it should be noted that the probabilities have been estimated for different M _f values in 15 regions. Comparing the model predictions with the actual earthquake occurrence rates shows the good performance of the model for Iranian plateau.  相似文献   

The eclipsing WN3(h)+O5V binary BAT99-129: Light curve analysis and parameters of its components     

I. I. Antokhin  A. M. Cherepashchuk 《Astronomy Reports》2007,51(6):486-499

We have analyzed the broad-band light curve of the massive eclipsing binary BAT99-129, which is located in the Large Magellanic Cloud and consists of WN3(h) and O5V components. The light curve was obtained as part of the MACHO project. The dense extended atmosphere of the Wolf-Rayet (WR) star makes it impossible to apply a standard parametric model, such as that of Wilson and Devinney, to analyze the light curve. We reconstructed the distributions of the brightness and absorption across the disk of the WR component by directly solving the integral equations describing the eclipses in the system. Our analysis yields reliable estimates of the system’s orbital parameters and the parameters of its components. The orbital inclination is 78°, the size of the orbit 28.5 R _⊙, and the radius of the O component R _O = 7.1 R _⊙. The size of the WR core, which is opaque in the optical continuum, is R _WR = 3.4 R _⊙, and the brightness temperature at the center of the WR-component disk is T _br = 45 000 K. We discuss possible uncertainties in the parameters obtained. The derived information is used to draw conclusions about the system’s evolutionary status.  相似文献   

Nonlinear radial pulsations of Wolf-Rayet stars     

Yu. A. Fadeev 《Astronomy Reports》2008,52(8):645-655

The evolution of Population I stars with initial masses 60 M _⊙ ≤ M _ZAMS ≤ 120 M _⊙ is computed up to the Wolf-Rayet stage, when the central helium abundance decreases to Y _c ≈ 0.05. Several models from evolutionary sequences in the core helium-burning stage were used as initial conditions when solving the equations of radiative hydrodynamics for self-exciting stellar radial pulsations. The low-density envelope surrounding the compact core during the core helium burning is unstable against radial oscillations in a wide range of effective temperatures extending to T _eff ～ 10⁵ K. The e-folding time of the amplitude growth is comparable to the dynamical time scale of the star, and, when the instability ceases growing, the radial displacement of the outer layers is comparable to the stellar radius. Evolutionary changes of the stellar radius and luminosity are accompanied by a decrease in the amplitude of radial pulsations, but, at the effective temperature T _eff ≈ 10⁵ K, the stellar oscillations are still nonlinear, with a maximum expansion velocity of the outer layers of about one-third the local escape velocity. The period of the radial oscillations decreases from 9 hr to 4 min as stellar mass decreases from M = 28 M _⊙ to M = 6 M _⊙ in the course of evolution. The nonlinear oscillations lead to a substantial increase of the radii of the Lagrangian mass zones compared to their equilibrium radii throughout the instability region. The instability of Wolf-Rayet stars against radial oscillations is due to the action of the κ mechanism in the iron-group ionization zone, which has a temperature of T ～ 2 × 10⁵ K.  相似文献   

Peculiarities and variations in the optical spectrum of the post-AGB star V448 Lac = IRAS 22223+4327     

V. G. Klochkova  V. E. Panchuk  N. S. Tavolzhanskaya 《Astronomy Reports》2010,54(3):234-246

Multi-epoch observations with high spectral resolution acquired in 1998–2008 are used to study the time behavior of the spectral-line profiles and velocity fields in the atmosphere and circumstellar shell of the post-AGB star V448 Lac. Asymmetry of the profiles of the strongest absorption lines with lower-level excitation potentials χ _low < 1 eV and time variations of these profiles have been detected, most prominently the profiles of the resonance lines of BaII, YII, LaII, SiII. The peculiarities of these profiles can be explained using a superposition of stellar absorption line and shell emission lines. Emission in the (0; 1) 5635 Å Swan system band of the C₂ molecule has been detected in the spectrum of V448 Lac for the first time. The core of the Hα line displays radial-velocity variations with an amplitude of ΔV _r ≈ 8 km/s. Radial-velocity variations displayed by weak metallic lines with lower amplitudes, ΔV _r ≈ 1–2 km/s, may be due to atmospheric pulsations. Differential line shifts, ΔV _r = 0–8 km/s have been detected on various dates. The position of the molecular spectrum is stationary in time, indicating a constant expansion velocity of the circumstellar shell, V _exp = 15.2 km/s, as derived from the C₂ and NaI lines.  相似文献   

Calorimetric Study of Natural Anapaite     

L. P. Ogorodova  L. V. Melchakova  M. F. Vigasina  D. A. Ksenofontov  I. A. Bryzgalov 《Geochemistry International》2018,56(4):397-401

The thermochemical study of natural hydrous calcium and iron phosphate, anapaite Ca₂Fe(PO₄)₂ · 4H₂O (Kerch iron ore deposit, Crimea, Russia), was carried out using high-temperature melt solution calorimetry with a Tian-Kalvet microcalorimeter. The enthalpy of formation of the mineral from elements was obtained to be Δ _f H_el°(298.15 K) =–4812 ± 16 kJ/mol. The values of the standard entropy and the Gibbs energy of anapaite formation are S°(298.15 K) = 404.2 J/K mol and Δ _f G_el°(298.15 K) =–4352 ± 16 kJ/mol, respectively.  相似文献   

Evolutionary status of the spectral variable BD + 48°1220 = IRAS 05040+4820     

V. G. Klochkova  E. L. Chentsov  N. S. Tavolzhanskaya  V. E. Panchuk 《Astronomy Reports》2007,51(8):642-674

Based on high-resolution observations (R = 60 000 and 75 000), we have studied the optical spectral variability of the star BD + 48°1220, identified with the IR source IRAS 05040+4820. We have measured the equivalent widths of numerous absorption lines of neutral atoms and ions at wavelengths from 4500 Å to 6760 Å, as well as the corresponding radial velocities. We use model atmospheres to determine the effective temperature T _eff = 7900 K, surface gravity log g = 0.0, microturbulence velocity ξ _t = 6.0, and the abundances for 16 elements. The star’s metallicity differs little from the solar value: [Fe/H] = ?0.10 dex. The main peculiarity of the chemical composition of the star is a large helium excess, derived from the Hel λ 5876 Å absorption, [He/H] = +1.04, and the equally large oxygen excess, [O/Fe] = +0.72 dex. The carbon excess is small, [C/Fe] = +0.09 dex, and the ratio [C/O] < 1. We obtained an altered relation for the light-metal abundances: [Na/Fe] = +0.87 dex with [Mg/Fe] = ?0.31 dex. The barium abundance is low, [Ba/Fe] = ?0.84 dex. It is concluded that the selective separation of elements onto dust grains of the envelope is probably efficient. The radial velocity of the star measured from photospheric absorption lines over three years of observations varies in the interval V _⊙ = ?(7–15) km/s. Time-variable differential line shifts have been revealed. The entire set of available data (the luminosity M _v ≈ ?5 ^m , velocity V _lsr ≈ ?20 km/s, metallicity [Fe/H] = ?0.10, and peculiarities of the optical spectrum and chemical composition) confirms the status of BD + 48°1220 as a post-AGB star with He and O excesses belonging to the Galactic disk.  相似文献