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1.
G. Scholz 《Astronomische Nachrichten》1981,302(6):279-284
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
2.
G. Scholz 《Astronomische Nachrichten》1979,300(4):213-217
Further investigations of the Ap star γ Equ (SCHOLZ , 1975) showed that a very slow variation of the longitudinal magnetic field exists, with a change of sign in the years 1970/1971. In three spectrograms obtained near of the crossover points of the longitudinal magnetic field hints are given at the presence of a transversal magnetic field of about 3500 Gauß. The radial velocity measurements show no definitive variations. 相似文献
3.
G. Scholz 《Astronomische Nachrichten》1978,299(6):305-309
The radial velocities of the Ap star 53 Cam = HD 65339 show a longtime variation corresponding to a binary motion. For the elements of the binary system the following values were derived: K = 8km/s, γ = -2.2 km/s, P = 2380 days. e = 0.56, ω = 10°, and a · sin i = 22 · 107 km. A second period of about 1850 days is indicated but this value seems to be a spurious period. Investigations of ZEEMAN spectrograms made by several authors gave a magnetic period of a bout 8 days. This period, interpreted as rotational period of the star, obviously differs a little for various observational times depending on the position in the binary orbit; so that the period is smaller at the time of the apastron passage. At present it is not possible to decide wheter this behaviour – if real – preponderantly reflects changes of the velocity of rotation or of the magnetic field. Furthermore the radial velocities show a dependence on the state of ionization of the elements in such a way that evidently lines from neutral elements have larger radial velocities (absolute values) than those of the ionized elements. These differences also depend on the position in the binary orbit as mentioned for the magnetic periods. 相似文献
4.
We present our synchronous spectroscopy and photometry of DI Cep, a classical T Tauri star. The equivalent widths and radial velocities of the individual components and Hα, Hβ, D1 and D2 Na I, and HeI λ5876 Å emission line profiles exhibit variability. We have found a clear positive correlation between the brightness and equivalent width for the Hα and Hβ emission lines. The photometric and spectroscopic data are satisfactorily described in phases of a 9-day period. The expected magnetic field of the star has been estimated using existing magnetospheric models to be 655–1000 G. The star is suspected to be a binary. 相似文献
5.
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
6.
The results of investigations of the Hα and Hβ lines in the spectrum of the star HD 206267 are presented. Observations were carried out in 2011–2014 at the Cassegrain focus of the 2-m telescope of the Tusi Shamakhy Astrophysical Observatory of the National Academy of Sciences of Azerbaijan using an echelle spectrometer. The following features have been revealed for the first time: the moving discrete absorption components in the core of the Hα line from the red side to the violet, the stable emission in the violet wing of the Hα line, the antiphase variation of the radial velocities and equivalent widths of the Hα line, and the independence of the changes of the equivalent widths of the Hβ line from the phase of the orbital period. No spectral features according to which this star could be considered as a source of X-ray radiation have been found. 相似文献
7.
We have studied the structure of hot accretion flow bathed in a general large-scale magnetic field. We have considered magnetic parameters , where are the Alfvén sound speeds in three direction of cylindrical coordinate (r,φ,z). The dominant mechanism of energy dissipation is assumed to be the magnetic diffusivity due to turbulence and viscosity in the accretion flow. Also, we adopt a more realistic model for kinematic viscosity (ν=αc s H), with both c s and H as a function of magnetic field. As a result in our model, the kinematic viscosity and magnetic diffusivity (η=η 0 c s H) are not constant. In order to solve the integrated equations that govern the behavior of the accretion flow, a self-similar method is used. It is found that the existence of magnetic resistivity will increase the radial infall velocity as well as sound speed and vertical thickness of the disk. However the rotational velocity of the disk decreases by the increase of magnetic resistivity. Moreover, we study the effect of three components of global magnetic field on the structure of the disk. We found out that the radial velocity and sound speed are Sub-Keplerian for all values of magnetic field parameters, but the rotational velocity can be Super-Keplerian by the increase of toroidal magnetic field. Also, Our numerical results show that all components of magnetic field can be important and have a considerable effect on velocities and vertical thickness of the disk. 相似文献
8.
I. I. Romanyuk E. A. Semenko D. O. Kudryavtsev A. V. Moiseevaa 《Astrophysical Bulletin》2016,71(3):302-313
We present the results of measuring longitudinal magnetic fields (Be), rotation velocities (ve sin i), and radial velocities (Vr) of 44 stars observed with the Main Stellar Spectrograph (MSS) of the 6-m BTA telescope of the Special Astrophysical Observatory in 2009. For the first time, magnetic fields were detected for the stars HD5441, HD199180, HD225627, and BD+00° 4535. We show that for the same stars, the longitudinal fields Be measured from the Hβ hydrogen line core and from metal lines can differ by 10% and up to a factor of 2–3. Except in rare cases, magnetic fields measured from the metal lines are stronger. We believe that this phenomenon is of a physical nature and depends on the magnetic field topology and the physical conditions inside a specific star. Observations of standard stars without magnetic fields confirm the absence of systematic errors capable of introducing distortions into the longitudinal-field measurement results. In this work we comment on the results for each of the stars. 相似文献
9.
D. N. Rustamov 《Astronomy Letters》2010,36(5):355-361
Based on 24 high-resolution echelle spectrograms of the Wolf-Rayet star HD 192163 taken in 2005–2007 at the Cassegrain focus of the 2-m Zeiss-2000 telescope at the Shemakha Astrophysical Observatory (National Academy of Sciences of Azerbaijan), we have investigated the profiles of five emission lines: He II 4859, He II 5411, CIV 5808, He I 5875, (He II + Hα) 6560. We have analyzed the echelle spectrograms using the DECH20 code. Various emission line parameters have been determined: the equivalent widths, radial velocities, central intensities, and FWHMs. The violet wing of the He II + Hα emission band has been found to be variable (from 6496 Å to 6532 Å). Significant differences in the equivalent widths and radial velocities of the He II + Hα emission band in 2005 and 2007 were revealed. This can be a manifestation of long-term variations in the star HD 192163. We have confirmed that HD 192163 belongs to the WN6 spectral subtype. 相似文献
10.
K. G. Strassmeier M. Weber T. Granzer L. Schanne J. Bartus I. Ilyin 《Astronomische Nachrichten》2014,335(9):904-934
We present continuous and time‐resolved R = 55 000 optical échelle spectroscopy of ε Aurigae from 2006–2013. Data were taken with the STELLA Echelle Spectrograph of the robotic STELLA facility at the Observatorio del Teide in Tenerife. Contemporaneous photometry with the Automatic Photoelectric Telescopes at Fairborn Observatory in Arizona is presented for the years 1996–2013. Spectroscopic observations started three years prior to the photometric eclipse and are still ongoing. A total of 474 high‐resolution échelle spectra are analyzed and made available in this paper. We identify 368 absorption lines of which 161 lines show the characteristic sharp disk lines during eclipse. Another 207 spectral lines appeared nearly unaffected by the eclipse. From spectrum synthesis, we obtained the supergiant atmospheric parameters Teff = 7395 ± 70 K, log g ≈ 1, and [Fe/H] = +0.02 ± 0.2 with ξt = 9 km s–1, ζRT = 13 km s–1, and v sin i = 28 ± 3 km s–1. The residual average line broadening expressed in km s–1 varies with a period of 62.6 ± 0.7 d, in particular at egress and after the eclipse. Two‐dimensional line‐profile periodograms show several periods, the strongest with ≈110 d evident in optically thin lines as well as in the Balmer lines. Center‐of‐intensity weighted radial velocities of individual spectral lines also show the 110‐d period but, again, additional shorter and longer periods are evident and are different in the Balmer lines. The two main spectroscopic Hα periods, ≈ 116 d from the line core and ≈ 150 d from the center‐of‐intensity radial velocities, appear at 102 d and 139 d in the photometry. The Hβ and Johnson V I photometry on the other hand shows two well‐defined and phase‐coherent periods of 77 d and 132 d. We conclude that Hα is contaminated by changes in the circumstellar environment while the Hβ and V I photometry stems predominantly from the non radial pulsations of the F0 supergiant. We isolate the disk‐rotation profile from 61 absorption lines and found that low disk eccentricity generally relates to low disk rotational velocity (but not always) while high disk eccentricity always relates to high velocity. There is also the general trend that the disk‐absorption in spectral lines with higher excitation potential comes from disk regions with higher eccentricity and thus also with higher rotational velocity. The dependency on transition probability is more complex and shows a bi‐modal trend. The outskirts of the disk is distributed asymmetrically around the disk and appears to have been built up mostly in a tail along the orbit behind the secondary. Our data show that this tail continues to eclipse the F0 Iab primary star even two years after the end of the photometric eclipse. High‐resolution spectra were also taken of the other, bona‐fide, visual‐binary components of ε Aur (ADS 3605BCDE). Only the C‐component, a K3‐4‐giant, appears at the same distance than ε Aur but its radial velocity is in disagreement with a bound orbit. The other components are a nearby (≈ 7 pc) cool DA white dwarf, a G8 dwarf, and a B9 supergiant, and not related to ε Aur. The cool white dwarf shows strong DIB lines that suggest the existence of a debris disk around this star. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
11.
New spectroscopic and photometric observations of the variable Ap star ET And carried out 1982 and 1983 confirm once again the existence of short-time variations. For the radial velocity variations a period of 0.19771 days and for the light variations a period of 0.0989 days was found. Some spectrograms show a velocity progression of the Balmer lines. The gradient is of such a kind that the radial velocity values increase from the line Hγ to H15. Different models for the interpreation of the velocity progression are discussed. 相似文献
12.
Dainis Dravins 《Solar physics》1975,40(1):53-63
Horizontal macroscopic velocities V hor in the photosphere are studied. High-resolution spectrograms of quiet regions are analyzed for center-limb variation of rms Doppler shifts. The data are treated to assure that the observed velocities refer to constant size volumes on the Sun (800 × × 3000 × 250 km), independent of μ. Using known height variation of vertical velocities and calculated line formation heights, the height dependence of 〈V hor〉 is obtained. From a value around 450 m s?1 it decreases rapidly with increasing height. To study also small-scale velocities, the time evolution of subarcsecond size elements in the photospheric network (solar filigree) is studied on filtergrams. It is concluded that they show proper motions implying 〈V hor〉 about 1 km s?1. 相似文献
13.
During August 1972, Explorer 45 orbiting near the equatorial plane with an apogee of ～5.2 Re traversed magnetic field lines in close proximity to those simultaneously traversed by the topside ionospheric satellite ISIS 2 near dusk in the L range 2.0–5.4. The locations of the Explorer 45 plasmapause crossings (determined by the saturation of the d.c. electric field double probe) during this month were compared to the latitudinal decreases of the H+ density observed on ISIS 2 (by the magnetic ion mass spectrometer) near the same magnetic field lines. The equatorially determined plasmapause field lines typically passed through or poleward of the minimum of the ionospheric light ion trough, with coincident satellite passes occurring for which the L separation between the plasmapause and trough field lines was between 1 and 2. Hence, the abruptly decreasing H+ density on the low latitude side of the ionospheric trough is not a near earth signature of the equatorial plasmapause. Vertical flows of the H+ ions in the light ion trough as detected by the magnetic ion mass spectrometer on ISIS were directed upward with velocities between 1 and 2 km s?1 near dusk on these passes. These velocities decreased to lower values on the low latitude side of the H+ trough but did not show any noticeable change across the field lines corresponding to the magnetospheric plasmapause. The existence of upward accelerated H+ flows to possibly supersonic speeds during the refilling of magnetic flux tubes in the outer plasmasphere could produce an equatorial plasmapause whose field lines map into the ionosphere at latitudes which are poleward of the H+ density decrease. 相似文献
14.
V. I. Kulidzanishvili 《Solar physics》1980,66(2):251-258
Almost simultaneous height sequences of 69 spicules in the Hα line have been studied. The spectra are obtained at six heights during 6 s on the east side of the solar disk with the 53-cm Lyot coronagraph of Abastumani Astrophysical Observatory. Radial velocities V r, total intensities or equivalent widths W, full widths at half maximum of intensity (FWHM) at all heights are determined (about 300 profiles of the Hα line). It is found that:
- Absolute values of radial velocities increase linearly with the height (see Equation (1));
- variation of the sign of the radial velocity along single spicules was never observed.
15.
Assuming that the orientation of a pulsar’s velocity vector is parallel to its spin axis, we have calculated the space velocities of 61 pulsars from their tangential velocities. The mean space velocity of the sample is equal to 267 km s-1. The radial velocities and kinematical ages of 20 pulsars are obtained. The decay time of the magnetic field of pulsars is τD = 2 Myr, smaller than previously found 相似文献
16.
The phenomenon of the sudden disappearance of equatorial sporadic E at two stations, namely, Trivandrum and Kodaikanal is studied. It is established that whenever there is a sudden disappearance of Es, there is a depression in the horizontal magnetic field (H) range. Electron velocities during the presence and absence of sporadic E have been estimated. These results show that the irregularities responsible for sporadic E are present even when the electron velocities are less than the ion thermal velocity. 相似文献
17.
G. Scholz 《Astronomische Nachrichten》1975,296(1):31-39
The determination of the radial velocity and the effective magnetic field strength for the peculiar A-type stars 53 Cam and γ Equ lad to the following results 53 Cam: The radial velocity shows a dependence on the excitation, resp. ionization potential in the way that evidently lines with higher excitation potential have higher radial velocity. We cannot explain this result with the rotator model without an essential modification of that. The amount and the time variation of the effective magnetic field agrees only approximately with that determined by BABCOCK. A secular variation may be indicated, but needs further confirmation. The effective magnetic field strength determined from the SiII-line λ = 4130.884 Å shows an essential smaller value than that by the other lines. The investigation of γ Equ yielded the following results: The best way to represent both the radial velocity and the effective magnetic field strength is a period of 1786 days given by STEINITZ and PYPER. We did not find a difference of the radial velocities derived from different lines and no line intensity variations. However, there seems to be observational evidence that short and obvious accidental variations of the radial velocity and effective magnetic field exist. 相似文献
18.
A dual étalon Fabry‐Pérot spectrometer called DEFPOS has been used for observing physical properties of HII regions and planetary nebulae since May 2007 (Aksaker et al. 2009, 2011; Şahan et al. 2009; Şahan 2011). In this study, the Hα measurements of the HII region NGC 1499 (California Nebula) have been investigated with a 4′ circular field of view over a 200 km s–1 (4.4 Å) spectral window. These measurements provide information about the densities, line widths, and radial velocities of the surrounding NGC 1499 nebula. The intensities, the radial velocities and the line widths of the Hα emission line vary from 397.75 R to 1044.14 R, –4.88 km s–1 to –1.02 km s–1, and 36.72 km s–1 to 42.81 km s–1, respectively (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
19.
We study the evolution of growth and decay laws for the magnetic field coherence length ξ, energy EM and magnetic helicity H in freely decaying 3D MHD turbulence. We show that with certain assumptions, self‐similarity of the magnetic power spectrum alone implies that ξ ∼ t1/2. This in turn implies that magnetic helicity decays as H ∼ t–2s, where s = (ξdiff/ξH)2, in terms of ξdiff, the diffusion length scale, and ξH, a length scale defined from the helicity power spectrum. The relative magnetic helicity remains constant, implying that the magnetic energy decays as EM ∼ t–1/2–2s. The parameter s is inversely proportional to the magnetic Reynolds number ReM, which is constant in the self‐similar regime. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
20.
We present the first infrared light curves of the binary V1430 Aql, in the bands J and K, plus V, R and I light curves and spectra covering the ranges of Hβ, Hα and Ca II-IRT lines. Our VRIJK data, together with published radial velocity curves, are analyzed to determine the orbital and stellar parameters of the system. Both stellar components present spectroscopic evidence of chromospheric activity, with emission excesses in the Hβ, Hα and Ca II-IRT lines. The measured ratio of the lines Hβ/Hα emission excesses can be interpreted as originated in plages. Our light curves also show photometric evidence of cool spots at least on one of the stars. 相似文献