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1.
We use 240 CCD spectra taken in 1998–2000 with the coude echelle spectrograph of the 2-m telescope of the National Academy of Sciences of Azerbaijan to study temporal radial velocity and line profile variations of the ion, HeI, and Hβ lines in the spectrumof the α Cyg supergiant. We demonstrate that these variations are caused by pulsation-type motions in the star’s atmosphere. Ion and HeI lines oscillate in the main fundamental mode with a period of about 12.0 ± 0.5 d and an amplitude of 5.0 ± 0.5 km/s. These ion-line oscillations continue for about 35 days. Then the difference between the radial velocities of strong and weak ion lines results in a gradual decay of oscillations over a time interval of about 5.0 ± 1.0 d . Thereafter the process repeats itself. For the Hβ line we found two significant periods, two amplitudes, and three characteristic radial velocity variability behaviors for the blue and red halves of the absorption profile: with equal variability parameters (period P and amplitude A); with equal P and A, but with a phase shift between the radial velocity variations of the blue and red halves of the absorption profile; with different P and A for the two halves of the absorption profile. The star’s center of mass radial velocity as inferred from the γ-velocity is −4.5 ± 0.5 km/s. The average expansion velocity of the atmospheric layers, where the Hβ line forms, amounts to about −16.5 ± 0.5 km/s and varies temporally with an amplitude of about 3.0 km/s.  相似文献   

2.
On the basis of 55 Zeeman spectrograms obtained at Tautenburg in the years 1975–1979 the effective magnetic fields and the radial velocities of the supergiant ν Cep (HD 207260) were determined. For the effective magnetic field a slow variation occurring on a time scale of years was found. The spectrograms taken at the first time show only moderate effective magnetic field strengths of a few hundred Gauß, but in the year 1978 values of +2000 Gauß were detected. The measured radial velocities show a longtime variability similar to that of the magnetic field as well as more rapid changes. A periodical variation of the radial velocity with a period of ∼ 39.9 days, perhaps produced by the rotation of the star, is indicated. The Balmer absorption lines Hβ, Hβ, and Hδ have different radial velocities refering to the presence of an expanding envelope. Moreover, there exist significant differences between the velocities of various elements respectively ions of 1–4 km/s.  相似文献   

3.
The CCD spectra taken with echelle spectrographs of the 2-m telescope of the Shemakha Astrophysical Observatory of the National Academy of Sciences of Azerbaijan and the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences are used to study the line profile variations in the spectrum of the hot supergiant 55Cyg. The variability of the radial velocity and profiles of the lines of heavy elements is shown to be due to radial pulsation type motions. The corresponding variations for He I lines are due to nonradial pulsations. In the case of the H β and H α lines the pattern and behavior of variations differ for different observing periods. The variability of these lines is mostly due to the photometric and positional variability of the absorption and emission components of their profiles. The profiles of these lines show additional emission components, which move from the blue toward the red line wing. Such a behavior is indicative of the clumpy structure of the stellar envelope.  相似文献   

4.
Investigation of 38 Zeeman spectrograms of the Be star EW Lac obtained in three successive years, 1978, 1979, and 1980, yield no hints at the occurrence of a global magnetic field larger than 150 Gauß. The temporal variations of the radial velocities of the Balmer and metallic absorption lines indicate a disturbance travelling through the envelope of EW Lac from the inner to the outer parts. The observed variations of the line widths and equivalent widths of the metallic lines suggest that the physical parameters remarkable change. These results together with the measured variations of the radial velocity and intensity of the emission features of Hβ can be explained by a thick elliptical ring surrounding EW Lac.  相似文献   

5.
Temporal variations of radial velocities and line profiles in the spectrum of the supergiant κ Cas were investigated. Variability of radial velocities and profiles of photospheric lines Si III, OII, He I, H10–Hδ and wind lines He I λ 5875, 6678 Å ismainly caused by non-radial pulsations. For photospheric lines quasisinusoidal variabilities of the radial velocity were found. Temporal variability of radial velocity of the wind lines He I λ 5875, 6678 A? differ from each other and from the photospheric lines. Gamma velocities and amplitudes of radial velocity variability were determined. The amplitude of variability and the velocity of expansion increase from lower to upper layers of the atmosphere. Emission components are superimposed on the line profiles at positions about ?135 ± 10.0, ?20 ± 20 and 135 ± 10.0 kms?1 respectively. They are more obvious in the wind line profiles, although, there are signs of emissions also in the photospheric lines. Such a character of variability of all the lines in the κ Cas spectrum confirms its Be nature.  相似文献   

6.
Fifty-three spectrograms in the optical region (3700–7300 Å) with the spectral resolution ～8 Å have been obtained for the Seyfert nucleus of the galaxy NGC 3227 with the 6-m telescope on January 1977, while the nucleus was in the historically important epoch of its extreme maximum brightness. Width of the slit was 1″, length of the box during the spectra measurements was 1.5″. Data obtained by us and those compiled from literature showed that profiles of the Balmer lines Hα, Hβ and Hγ are different, evidencing that the gas emitting these lines is highly self-absorbed. It was shown that narrow components of the profiles revealed by Rubin and Ford kept their positions (radial velocities) over 25 years. The components showed intensity variations compared to the central one from minimum to maximum of the nucleus brightness. The same variations were observed by us earlier in the emission line profiles of the NGC 7469 nucleus spectrum. Narrow profile components can reflect long-lived flows or jets in the broad line region (BLR). Obtained facts evidenced that long-lived gas streams and flows causing narrow components of broad line profiles presented not only when BLR of accretion disc is strong but when BLR of accretion disc declined. Blue bump at radial velocity of ?5000 km/s in Hγ profile was revealed in spectra of high states of the nucleus, which disappeared in low state. One of the interpretations of this event can be in the framework of a model of one-sided or two-sided gas ejection during the high state of the nucleus, positive radial velocities of which being screened out by a circumnuclear disk.  相似文献   

7.
We present differential Hα and Hβ photometry of the very bright RS CVn‐binary α Aurigae (Capella)obtained with theVienna automatic photoelectric telescope in the years 1996 through 2000. Low‐level photometric variations of up to 0m.04 are detected in Hα. A multifrequency analysis suggests two real periods of 106 ± 3 days and 8.64 ± 0.09 days, that we interpret to be the rotation periods of the cool and the hot component of the Capella binary, respectively. These periods confirm that the hotter component of Capella rotates asynchronously, while the cooler component appears to be synchronized with the binary motion. The combined Hα data possibly contains an additional period of 80.4 days that we, however, believe is either spurious and was introduced due to seasonal amplitude variations or stems from a time‐variable circumbinary mass flow. The rotational periods result in stellar radii of 14.3 ± 4.6 R⊙ and 8.5 ± 0.5 R⊙ for the cool and hot component, respectively, and are in good agreement with previously published radii based on radiometric and interferometric techniques. The long‐period eclipsing binary Aurigae served as our check star, and we detected complex light variations outside of eclipse of up to 0m.15 in H α and 0m.20 in Hβ. Our frequency analysis suggests the existence of at least three significant periods of 132, 89, and 73 days. One of our comparison stars (HD 33167, F5V) was discovered to be a very‐low amplitude variable with a period of 2.6360 ± 0.0055 days.  相似文献   

8.
The radial velocity, intensity variations of the Caii line and chemical composition of the suspected magnetic star HD 151 199 have been studied using three 9.6 A/mm and twenty-one 40 A/mm dispersion spectrograms which were taken at St. Michel and Asiago Observatories respectively. The radial velocity and the intensity of the Caii K line suggest a variation with a 6.143 day period. The range is about 40 km/sec for the radial velocity and the K line changes in intensity by 50%. Preliminary results of the photometric data in the Geneva system show a similar trend of variation in (B 2–B 1) with the same period. H and H contours and the Balmer discontinuity give eff=0.50 and logg=4. The most probable microturbulence is found to be 6.4 km/sec. The excitation temperature, exc=0.50, is derived from the Fe lines and adopted for the other elements as well. A quantitative analysis by curve of growth and weighting function method, using Mihalas and Conti's atmospherical models was made. HD 151 199 shows an overabundance of Ca, Sr, Ba, by factors of 2, 40, and 5 with respect to 30 L Mi. Euii is probably overabundant also but it is not possible to give this element a numerical value. The other elements seem to be normal.  相似文献   

9.
We have established that the cataclysmic variable TU Crateris is an SU UMa star. Superhumps were observed after 3 days of the 1998 March-April supermaximum, repeating with a mean period of Ps = 0d.08535(5). Timings of superhump maxima revealed a period decrease of P = 7.2 × 10-5. Based on an empirical relationship, we estimated an orbital period of 0d.0810(25), just in the lower limit of the reported quiescence photometric period. H emission lines during quiescence vary with the orbital period with radial velocity half amplitude of 70 ± 19 km s-1, evidencing a hotspot located in front of the standard position.  相似文献   

10.
The radial velocity variations of the components of someOii, Siiii, andNii lines in P Cyg spectrum are investigated during the period 1981–1983. All data are analyzed in terms of a model which implies a multiple ejection of shells in the stellar wind. It is shown that the observed phenomenon is not periodic, but it occurs on a time-scale between 110 and 160 days with the most frequently observed length of the cycle of about 110 days. The shells move away from the star with an acceleration that is greater at low velocities than at high ones. The radial velocity variations ofOii, Siiii, andNii lines agree with these of hydrogen lines if we assume velocity and excitation condition differences inside the shell.  相似文献   

11.
We measured the radial velocity of the star θ1 Ori D from IUE spectra and used published observations. Based on these data, we determined the period of its radial-velocity variations, P=20.2675±0.0010 days, constructed the phase radial-velocity curve, and solved it by least squares. The spectroscopic orbital elements were found to be the following: the epoch of periastron passage Ep=JD 2430826.6±0.1, the system's center-of-mass velocity /Gg=32.4±1.0 km s?1, K=14.3±1.5 km s?1, Ω=3.3±0.1 rad, e=0.68±0.09, a1 sin i = 3 × 1010 km, and f1 = 0.0025M⊙. Twice the period, P=40.528±0.002 days, is also consistent with the observations.  相似文献   

12.
We report an efficient method for analyzing the radial-velocity and line-profile variability. We show that a detailed analysis of the variations of line profiles and velocity field in the stellar atmosphere requires the radial velocities to be measured separately for the blue and red halves of the absorption lines at different levels of their residual intensity. We applied this method to 120 CCD spectra taken in 1998–99 with the coude echelle spectrograph attached to the 2-m telescope of Shemakha Astronomical Observatory of National Academy of Sciences of Azerbaijan and analyzed the variations of the radial velocities and profiles of ion and Hβ lines in the spectrum of α Cyg. In the case of ion lines both halves of the absorption profile exhibit synchronous radial-velocity variations at all levels of line intensity. In the case of the Hβ line, which forms in the layers where stellar wind originates, the pattern of radial-velocity variations differs for the blue and red halves of the absorption profile. The variability pattern is the same at all levels in the red half of the profile, the blue half of the profile exhibits different variability patterns at different levels of residual line intensity. Identification and analysis of such variations allows us to study the nature of stellar-wind variability in the region of wind formation.The spectrum of α Cyg showed no line-profile or radial-velocity variations for six days in both halves of the absorption contour at all levels of line intensity. The star was in the quiescent phase.  相似文献   

13.
The variability of positional and photometric parameters of the lines in the spectrum of HD 93521 is analyzed using CCD spectra taken with the PFES echelle spectrograph of the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS). To study the velocity field of the star’s atmosphere, the radial velocity variations are measured separately for the blue and red halves of the absorption profile at different levels of residual line intensity. The amplitude and phase of temporal variations of radial velocity differ for the two halves of the absorption profile. In case of strong HeI, Hβ, andHα lines the amplitude depends on intensity r. The time scales (P) of radial velocity variations and the mean halfwidths \(\overline {FW H M} \) differ for different lines and correlate fairly well with their central depths. The increase of P and decrease of \(\overline {FW H M} \) from weak to strong lines are due to the differential nature of the rotation of the star. Our analysis proofs that HD 93521 is a run-away star and this fact explains its location at a distance of about 2.0 kpc above the Galactic plane.  相似文献   

14.
The results of quasi-simultaneous spectroscopic and photometric observations of a W UMatype eclipsing variable star AM Leo are presented. The observations were carried out with a 1.2-m telescope equipped with a high-resolution echelle spectrometer, and a telescope-reflector (D = 0.45m) of the Kourovka Astronomical Observatory of Ural Federal University. New values of semi-amplitudes of the radial velocity curves of the components, K1 = 109.6kms?1 and K2 = 252.4kms?1 and the systemic radial velocity V0 =-9.3 kms?1 are obtained, comparable to the data published in the literature. The semi-amplitude of the radial velocity curve of a more massive component K1 and the mass ratio of the components q = 0.412 appeared to be slightly smaller than the values obtained by other authors. An assumption wasmade that a possible reason of this is the presence of hot and/or cold spots on the surface of the components, shifting the effective center of brightness of the visible disk of the component with respect to its center of mass position. It was shown that the AM Leo light curve variations on the time scales of one and more days, registered within the photometric part of the study may be described by the choice of appropriate model of the spot structure.  相似文献   

15.
We present the results of spectroscopic and photometric studies of a new polar CRTS CSS130604 J 215427+155714, conducted at the telescopes of the SAO RAS. Analysis of the photometric series of observations allowed to clarify the orbital period of the system, P o = 0. d 0672879 (±0.0000003). We build radial velocity curves and trace the intensity variations in the Hβ and Hγ hydrogen lines and He II λ 4686 ?A ionized heliumline. Based on the Hβ and He II lines we build Doppler maps. It is shown that the line formation region is localized near the Lagrange point. The following parameter estimates of the system are obtained:M 1 = 0.83 ± 0.10M ⊙, M 2 = 0.15 ± 0.01M ⊙, q = M 2/M 1 = 0.18 ± 0.03, i = 53? ± 5?. Based on the results of spectral, photometric and previously published polarimetric observations the possible geometric model of the system is discussed.  相似文献   

16.
The variations of kinematic parameters with age are considered for a sample of 15 402 thin-disk O-F stars with accurate ??, ??, ??, and ?? > 3 mas from the Hipparcos catalogue and radial velocities from the PCRV catalogue. The ages have been calculated from the positions of the stars on the Hertzsprung-Russell diagram relative to the isochrones from the Padova database by taking into account the extinction from the previously constructed 3D analytical model and extinction coefficient R V from the 3D map of its variations. Smooth, mutually reconciled variations of the velocity dispersions ??(U), ??(V), ??(W), solar motion components U ??, V ??, W ??, Ogorodnikov-Milne model parameters, Oort constants, and vertex deviation l xy consistent with all of the extraneous results for which the stellar ages were determined have been found. The velocity dispersion variations are well fitted by power laws the deviations from which are explained by the influence of predominantly radial stellar streams: Sirius, Hyades, ?? Cet/Wolf 630, and Hercules. The accuracy of determining the solar motion relative to the local standard of rest is shown to be fundamentally limited due to these variations of stellar kinematics. The deviations of our results from those of Dehnen and Binney (1998), the Geneva-Copenhagen survey of dwarfs, and the Besan con model of the Galaxy are explained by the use of PCRV radial velocities with corrected systematic errors.  相似文献   

17.
The results of radial velocity measures of the star o And from high dispersion plates relative to the years 1964, 1966, 1975 and 1976 are given. The averaged values of the 1964 and 1966 plates confirm the existence of the minimum in the trend of the radial velocities and fit well the curve obtained in the hypothesis of periodic long-term radial velocity variations with the period of 23.5 years (Fracassiniet al., 1977). Preliminary orbital elements in the hypothesis of a long period spectroscopic binary system have been tentatively drawn.  相似文献   

18.
High resolution echelle spectroscopic observations taken with the FEROS spectrograph at the 2.2 m telescope ESO confirm the binary nature of the flare M3.5V star LU Vel (GJ 375, RE J0958-462) previously reported by Christian and Mathioudakis (2002). Emission of similar intensity from both components is detected in the Balmer, Na i D1&D2, He i D3, Ca ii H&K, and Ca ii IRT lines. We have determined precise radial velocities by cross correlation with radial velocity standard stars, which have allowed us to obtain for the first time the orbital solution of the system. The binary consists of two near-equal M3.5V components with an orbital period shorter than 2 days. We have analyzed the behaviour of the chromospheric activity indicators (variability and possible flares). In addition, we have determined its rotational velocity and kinematics.  相似文献   

19.
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   

20.
Based on observations with the 6-m SAO RAS telescope, we have found that chemically peculiar star with a large depression of the continuum at λ5200 Å and strengthened silicon lines in the spectrum has a strong magnetic field. The longitudinal field component Be has a negative polarity and varies from ?300 G to ?2000 G with a period of 1.756 days. Photometric variations of brightness take place with the same period. We determined the variability of the radial velocity at times of about tens of years pointing to a possible binarity of the object. We have built a magnetic model of this star, determined the inclination angles of the rotation axis to the line of sight i = 20° and of the dipole axis to the rotation axis β = 116°, and the field strength at the pole is Bp = 10 kG. We carried out a chemical composition analysis and found a lack of helium for almost an order of magnitude, some overabundance of silicon and metal elements for more than an order of magnitude, particularly, cobalt for three orders of magnitude.  相似文献   

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