共查询到20条相似文献，搜索用时 37 毫秒
1.
Yu. V. Glagolevskij 《Astrophysical Bulletin》2009,64(1):62-71
The method of “magnetic charges” is used to model magnetic fields of five rapidly rotating stars (P < 25d) and to find the basic parameters of their magnetic fields. A table containing all the modeling results obtained using the adopted method as well as the parameters obtained for the same stars by other authors is presented. Significant discrepances are found in a number of cases, which can apparently be explained by insufficient accuracy of the estimated inclinations of the stars to the line of sight. 相似文献
2.
We model magnetic fields of seven magnetic stars using a program for studying the structure of magnetic fields in CP stars.
It appears that five of them clearly manifest the structure of a central dipole, and the remaining two can be explained by
a shifted dipole model. Our previous research and the results of this study demonstrate that the dipole orientation inside
the stars relative to the rotation axis can vary from 0° to 90°, both for fast and slow rotators. We can not yet solve the
question of the existence of a dominant orientation due to lack of statistics. Our modeling results are consistent with those
calculated using Preston’s technique in the case of a dipole field configuration. 相似文献
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Yu. V. Glagolevskij 《Astrophysical Bulletin》2010,65(1):34-41
We model the magnetic fields of four magnetic stars using published longitudinal (Be) field measurements. The structure of
the magnetic field of each of the four stars is close to that of the central dipole. Unfortunately, the number of measurements
for each star is insufficient for accurate finding of the field parameters, and therefore we find no dipole shift exceeding
its error Δa ≈ 0.1, expressed as a fraction of the stellar radius. Our data support the opinion that the results of modeling depend most
strongly on the adopted inclination of the star’s rotation axis i. 相似文献
5.
Our spectroscopic monitoring of the hypergiants HD 168607 (B9.5 Ia-0) and HD 168625 (B5.5 Ia-0) with resolutions from 15000 to 70000 confirms that both stars belong to the Ser OB1 association, proves their spatial closeness, and increases the probability that they constitute a physical pair. 相似文献
6.
Astronomy Letters - We present the results of our determination of the fundamental atmospheric parameters for the magnetic chemically peculiar Ap stars HD 110066 (AX CVn) and HD 153882 (V451 Her).... 相似文献
7.
I. I. Romanyuk E. A. Semenko I. A. Yakunin D. O. Kudryavtsev A. V. Moiseeva 《Astrophysical Bulletin》2017,72(2):165-177
We present the results of magnetic field measurements of four chemically peculiar (CP) stars with helium abundance anomalies which are the members of the Orion stellar association OB1. The stars under study were classified as magnetic by other authors earlier. The present paper contains the results of the extensive study of the stars. Magnetic field measurements allowed us to conclude that HD36540 has a weak field and the longitudinal component B e does not exceed 500 G. The longitudinal field of HD36668 varies with the period P = 2. d 11884 and the amplitude from ?2 to +2 kG. The magnetic field of HD36916 has mainly negative polarity and varies within the range from 0 to ?1 kG with the period P = 1.d 565238. HD37058 is a magnetic star, the longitudinal field of which varies from ?1.2 to +0.8 kG with the period P = 14. d 659. The B e field variability pattern for the stars HD36916 and HD37058 is of a simple harmonic type. The longitudinal field of HD36668 is best described with two combined harmonic functions (“a doublewave”). The variability period of HD36540 is still undetermined. For all the stars from this paper, we measured radial velocities V r, axial rotation rates v e sin i, and determined basic parameters of atmospheres (effective temperatures T eff and gravity acceleration log g). We also estimated masses M, luminosities L, and radii R of the stars. 相似文献
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Yu. V. Glagolevskii 《Astrophysics》2001,44(1):98-105
The magnetic fields of the chemically peculiar stars HD 115708 and HD 119419 were modeled using observed curves of variation of the magnetic field with the phase of the rotational period. It turned out that the field of HD 115708 is described, in a first approximation, by a central dipole, while the field of HD 119419 is described by an off-center dipole. The main parameters of the magnetic fields of both stars and maps of the surface field-strength distribution were obtained. The dipole axis of the first star lies in the equatorial plane while that of the second is almost parallel to the axis of rotation. 相似文献
10.
I. I. Romanyuk E. A. Semenko I. A. Yakunin D. O. Kudryavtsev A. V. Moiseeva 《Astrophysical Bulletin》2016,71(4):436-446
We present the results of magnetic field measurements of four chemically peculiar (CP) stars, the members of the Orion stellar association OB1. Observations were carried out with the circular polarization analyzer at the Main Stellar Spectrograph of the 6-m telescope. All the studied stars refer to the subtype of Bp stars with weak helium lines. Canadian astronomer E. F. Borra detected a magnetic field in three of them (HD35456, HD36313, and HD36526) from the Balmer line magnetometer observations. HD35881 was observed for the first time for the purpose to search for a magnetic field. We obtained the following results: HD35456 is a magnetic star with longitudinal field variation range from +300 to +650 G and a period of 4.9506 days; HD35881 is possible a new magnetic star, the longitudinal component of which varies from?1 to +1 kGwith a period of 0.6998 days, however, a small number of lines broadened by rotation does not allow us to conduct measurements more accurately; HD36313 is a binary star with the components similar in brightness, the primary component is a magnetic star with broad lines, the magnetic field of the secondary component (the star with narrow lines) was not detected. Measurements in the Hβ hydrogen line showed the variations of the longitudinal component from ?1.5 to +2 kG with a period of 1.17862 days; a strong longitudinal field was detected in HD36526 (from 0 to +3000 G) varying with a rotation period of the star of 3.081 days. In all the cases, we observe considerable discrepancies with the data on magnetic fields of these objects obtained earlier. 相似文献
11.
HD 115781 and HD 116204 (BL CVn and BM CVn) are shown to be RS CVn binaries with periods near 20 days. HD 115781 is double-lined;
the primary type is about K1III, while the secondary is probably a late-type subgiant. The masses of the two components are equal within observational error.
There is substantial photometric variability with a period half the orbital period; it is attributed to ellipsoidal variation.
HD 116204 is also of type K1III. It shows exceptionally strong Ca II H and K emission, together with an emission-line spectrum typical of RS CVn stars in
theIUE ultraviolet region, but Hα is an absorption line. The secondary star in the HD 116204 system has not been detected. The primary
shows photometric variations, presumably due to starspots, with a period 5 per cent longer than the orbital period. 相似文献
12.
根据贫金属星个别重元素丰度的观测值和太阳系重核素的ｒ过程和ｓ过程分量的丰度分布,计算了贫金属星ＨＤ２０３６０８和ＨＤ２１１９９８的重元素丰度并与观测进行了比较。结果表明,太阳系纯ｒ过程和ｓ过程元素丰度均不能拟合出这二颗样品星的丰度观测值,而应同时考虑ｒ过程和ｓ过程的贡献 相似文献
13.
陆文贤 《中国天文和天体物理学报》1990,(2)
使用加拿大自治领天体物理台(DAO)的视向速度仪及光栅摄谱仪,获得了分光双星HD144515和HD178428的新的视向速度。结合文献中前人的观测资料,HD144515的轨道运动周期测定为4.285439±0.000009天;HD178428的为21.95582±0.00032天。HD144515的速度曲线的半变幅K有重要的改进。两双星的轨道偏心率e获得显著的修正。 相似文献
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We present a study of stratification of helium and silicon in the atmospheres of CP stars HD 168785 (He-r) and HD 21699 (He-w).
The distribution of these elements with depth is well described by the mechanism of diffusion under the effect of gravity,
radiation pressure and stellar wind. We studied the stratification of these elements in different regions of the surface of
HD 21699. We demonstrate that as the star rotates the abundance of He and Si changes in the antiphase. The position of the
abundance maximum varies within small limits with optical depth as well. 相似文献
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We report the discovery of brightness variability in the IR-excess early F supergiant HD 331319, a candidate post-AGB star.
Over three years of systematic U BV observations, the star showed low-amplitude (up to
in V) quasi-periodic brightness variations on a time scale of ∼45 days. A preliminary analysis of our photometry indicates that
HD 331319 and other typical post-AGBF supergiants have a similar pattern of variability. A study of the extinction toward
HD 331319 leads us to conclude that the fraction of the circumstellar extinction is small for this star. We present low-resolution
spectroscopy for HD 331319 and discuss the spectral classification of post-AGB F supergiants using HD 331319, HD 161796, HD
187885, and HD 56126 as examples. 相似文献
19.
This is the final paper on a study of the magnetic field structure of CP stars with long rotation periods. It is first demonstrated
that the orientation and strength of the magnetic field have no effect on their rotation velocity. The orientation of the
dipole structures in slow magnetic rotators is shown to be random, as it is in fast rotators. The hypothesis that magnetic
stars are slowed down under the influence of the magnetic field is called into question. The origin of CP stars is probably
related to their initial slow rotation.
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Translated from Astrofizika, Vol. 51, No. 2, pp. 295–303 (May 2008). 相似文献
20.
We investigate the HD 182255, a star earlier suspected to be helium-weak. We show it to be a SiHe-w-type CP object. Our study
revealed four regions with anomalous elemental abundances on the stellar surface near the equator of rotation. Its magnetic
field could not be measured, apparently due to the unfavorable orientation of the star. The star is seen almost (rotation)
pole on, the inclination of its rotation axis is i = 12°. The magnitude of HD 182255 varies as a result of its rotation owing to the nonuniform distribution of chemical elements
on its surface, which leads to the variable blanketing effect. The helium and silicon abundances increase with depth, i.e.,
the stratification typical of CP stars is observed. The star undergoes nonradial pulsations and nonstationary variations of
the structure of its upper atmosphere. 相似文献