Unified view and interpretation of peculiar pulsation features in roAp stars, RR Lyrae stars, Early-type stars
Unified view and interpretation of peculiar pulsation features in roAp stars, RR Lyrae stars, Early-type stars
批准号:
11440061
负责人:
SHIBAHASHI Hiromoto
金额:
$3.26万
依托单位:
依托单位国家:
日本
项目类别:
Grant-in-Aid for Scientific Research (B).
财政年份:
1999
资助国家:
日本
项目状态:
已结题
起止时间:
1999 至 2000
中文摘要
我讨论了快速振荡的AP星的振荡特征、天琴座RR恒星的布拉日科效应和β造父变星,并将它们解释为恒星振荡本征函数的磁扰动的表现。RoAp星的脉动幅度随磁场变化而同步变化,且振幅最大位相与磁极大位相重合。我讨论了哪些信息是可用的,并概述了它是如何从观测数据中推断出来的。我们讨论了β造父变星的振荡特征,它是一颗磁轴似乎与自转轴成斜角的磁星。我将观察到的频谱的等距精细结构解释为本征模的磁扰动的表现,在没有磁场的情况下,本征模将是径向模。除了这些频率分量,我将频谱中的另一个峰值解释为独立的四极模。通过模式识别,推导出β造父变星的质量、演化阶段、自转频率、磁场强度和几何构型。通过假设天琴座RR星具有相当强的偶极子磁场,且对称轴与恒星的旋转轴成斜角,我证明了在没有磁场的情况下振荡模式是纯径向振荡,它有一个四极分量,其对称轴与磁轴重合。四极分量的方位角随恒星自转而变化,这种明显的振幅变化被解释为天琴座RR恒星中的Blazhko效应。结果表明,在离轴磁场的情况下,位相调制是可望的。我列出了一些基于该模型的理论预测,这些预测将从观测上检验这一假设。
英文摘要
I discuss the oscillation features of the rapidly oscillating Ap stars, the Blazhko effect of the RR Lyrae stars, and β Cephei and interpret them as being a manifestation of a magnetic perturbation to the oscillation eigenfunctions of the stars.1. The pulsation amplitude of the roAp stars varies synchronously with the magnetic variation, and the amplitude maximum phase coincides with the magnetic maximum phase. I discuss what kind of information is available and outline how it is deduced from the observational data.2. I discuss the oscillation features of β Cephei, which is a magnetic star in which the magnetic axis seems to be oblique to the rotation axis. I interpret the observed equi-distant fine structure of the frequency spectrum as a manifestation of a magnetic perturbation of an eigenmode, which would be a radial mode in the absence of the magnetic field. Besides these frequency components, I interpret another peak in the frequency spectrum as an independent quadrupole mode. By this mode identification, I deduce the mass, the evolutionary stage, the rotational frequency, the magnetic field strength, and the geometrical configuration of β Cephei.3. By assuming that RR Lyrae stars have fairly strong dipole magnetic fields with symmetry axis oblique to the rotation axis of the star, I show that the oscillation mode which would be a pure radial oscillation in absence of the magnetic field has a quadrupole component, whose symmetry axis coincides with the magnetic axis. The aspect angle of the quadrupole component changes due to the stellar rotation, and this apparent amplitude variation is interpreted as the Blazhko effect in RR Lyrae stars. It is shown that, in the case of off-axis magnetic field, the phase modulation is expected. I list up some theoretical predictions based on this model, which would observationally examine this hypothesis.
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Shibahashi,H.,& Aerts,C.: "Asteroseismology and Oblique Pulsator Model of β Cephei"Astrophys.J.Letters. 531. L143-L146 (2000)
Shibahashi, H., & Aerts, C.:“仙王星的星震学和倾斜脉动模型”Astrophys.J.Letters 531. L143-L146 (2000)
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共 21 条
Asteroseismology based on high time-resolution and high dispersion spectroscopy
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批准号:23540260
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项目类别:Grant-in-Aid for Scientific Research (C)
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资助金额:$3.16万
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财政年份:2011
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负责人:SHIBAHASHI Hiromoto
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依托单位:
Nonradial oscillations of tidally distorted stars and asteroseismology
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批准号:13640232
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项目类别:Grant-in-Aid for Scientific Research (C)
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资助金额:$1.92万
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财政年份:2001
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负责人:SHIBAHASHI Hiromoto
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依托单位:
Helioseismic Study of Solar Internal Rotation
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批准号:08454048
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项目类别:Grant-in-Aid for Scientific Research (B)
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资助金额:$4.48万
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财政年份:1996
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负责人:SHIBAHASHI Hiromoto
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依托单位:
Deduction of the solar internal structure from the sound speed profile in the sun and estimates of the solar neutrino fluxes based on the heliseismic data
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批准号:06452018
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项目类别:Grant-in-Aid for General Scientific Research (B)
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资助金额:$4.74万
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财政年份:1994
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负责人:SHIBAHASHI Hiromoto
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依托单位:
Determination of an Instability Strip of Long Period Variables
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批准号:04640266
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项目类别:Grant-in-Aid for General Scientific Research (C)
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资助金额:$1.41万
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财政年份:1992
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负责人:SHIBAHASHI Hiromoto
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依托单位: