排序方式： 共有40条查询结果，搜索用时 140 毫秒
11.
M. S. Cunha C. Aerts J. Christensen-Dalsgaard A. Baglin L. Bigot T. M. Brown C. Catala O. L. Creevey A. Domiciano de Souza P. Eggenberger P. J. V. Garcia F. Grundahl P. Kervella D. W. Kurtz P. Mathias A. Miglio M. J. P. F. G. Monteiro G. Perrin F. P. Pijpers D. Pourbaix A. Quirrenbach K. Rousselet-Perraut T. C. Teixeira F. Thévenin M. J. Thompson 《Astronomy and Astrophysics Review》2007,14(3-4):217-360
Asteroseismology provides us with a unique opportunity to improve our understanding of stellar structure and evolution. Recent developments, including the first systematic studies of solar-like pulsators, have boosted the impact of this field of research within astrophysics and have led to a significant increase in the size of the research community. In the present paper we start by reviewing the basic observational and theoretical properties of classical and solar-like pulsators and present results from some of the most recent and outstanding studies of these stars. We centre our review on those classes of pulsators for which interferometric studies are expected to provide a significant input. We discuss current limitations to asteroseismic studies, including difficulties in mode identification and in the accurate determination of global parameters of pulsating stars, and, after a brief review of those aspects of interferometry that are most relevant in this context, anticipate how interferometric observations may contribute to overcome these limitations. Moreover, we present results of recent pilot studies of pulsating stars involving both asteroseismic and interferometric constraints and look into the future, summarizing ongoing efforts concerning the development of future instruments and satellite missions which are expected to have an impact in this field of research. 相似文献
12.
Maria Pia Di Mauro JØrgen Christensen-Dalsgaard Lucio Paternò Francesca D'Antona 《Solar physics》2004,220(2):185-198
HR 5235, better known as η Bootis, is a bright and well-known star for which very accurate observations have recently enabled
Kjeldsen et al. (2003) and Carrier, Bouchy, and Eggenberger (2003) not only to confirm the presence of solar-like oscillations, but also
to identify the excitation in the oscillation spectrum of several p-mode frequencies with harmonic degrees l = 0 – 2. Here we show how such observational success, through the calculation and the investigation of theoretical structure
models and the comparison of the observed oscillation spectra with the predicted p-mode frequencies of oscillations, permits one to draw conclusions about the actual evolutionary state of this star and on
the physical properties of its internal structure. The computation of the structure models is based on the use of updated
global parameters and includes overshooting from the convective core. In particular, we consider the effect on the stellar
structure, and hence on the theoretical frequencies, of employing different equations of state and different formalisms to
describe the convective energy transport. 相似文献
13.
Philip H. Scherrer John M. Wilcox J. Christensen-Dalsgaard D. O. Gough 《Solar physics》1983,82(1-2):75-87
Solar five-minute oscillations of degree l = 3, 4, and 5 have been observed at Stanford, in the Doppler shift of the Fe 5124 line. The frequencies and amplitudes are in broad agreement with previous observations of modes with l ≤ 3, though we note that there are some systematic discrepancies between the results of different observers. 相似文献
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Rotational enhancement of the sensitivity of whole-disk Doppler observations of solar oscillations may permit the measurement of five-minute modes with l = 4. We estimate from superposed power spectra of artificial solar data that there might be identifiable power lying above the noise in the data acquired by Pallé et al. (1986), which could provide confirmation of the rotational splitting measured by Duvall and Harvey (1984). 相似文献
17.
Jørgen Christensen-Dalsgaard 《Astrophysics and Space Science》1998,261(1-4):1-12
18.
F.Pérez Hernández J.Christensen-Dalsgaard 《Monthly notices of the Royal Astronomical Society》1998,295(2):344-352
In recent years there has been some progress towards detecting solar-like oscillations in stars. The goal of this challenging project is to analyse frequency spectra similar to that observed for the Sun in integrated light. In this context it is important to investigate what can be learned about the structure and evolution of the stars from such future observations. Here we concentrate on the structure of the upper layers, as reflected in the phase function. We show that it is possible to obtain this function from low-degree p modes, at least for stars on the main sequence. We analyse its dependence on several uncertainties in the structure of the uppermost layers. We also investigate a filtered phase function, which has properties that depend on the layers around the second helium ionization zone. 相似文献
19.
H. Otí Floranes J. Christensen-Dalsgaard M. J. Thompson † 《Monthly notices of the Royal Astronomical Society》2005,356(2):671-679
The systematic patterns of separations between frequencies of modes of different degree and order are a characteristic of p-mode oscillations of stars. The frequency separations depend on the internal structure of the star and so measuring them in the observed oscillation spectra of variable stars gives valuable diagnostics of the interior of a star. Roxburgh & Vorontsov proposed using the ratio of the so-called small frequency separation to the large frequency separation as a diagnostic of the stellar interior, and demonstrated that this ratio was less sensitive than the individual frequency separations themselves to uncertain details of the near-surface structure. Here we derive kernels relating the frequency separation ratio to structure, and show why the ratio is relatively insensitive to the near-surface structure in terms of the very small amplitude of the kernels in the near-surface layers. We also investigate the behaviour of the separation ratio for stars of different masses and ages, and demonstrate the usefulness of the ratio in the so-called asteroseismic Hertzsprung–Russell diagram. 相似文献
20.
J. Christensen-Dalsgaard M. P. Di Mauro H. Schlattl A. Weiss 《Monthly notices of the Royal Astronomical Society》2005,356(2):587-595
An important goal of helioseismology is to provide information about the basic physics and parameters that determine the structure of the solar interior. Here we discuss the procedures applied in such analyses, using as an example attempts to obtain significant constraints on the value of Newton's gravitational constant G from helioseismology. The analysis is based on complete direct and inverse helioseismic analysis of a set of accurate observed acoustic frequencies. We confirm, as found by previous investigations based on different approaches, that the actual level of precision of the helioseismic inferences does not allow us to constrain G with a precision better than that which can be reached with direct experimental measurements. The conclusion emphasizes the importance in helioseismic inferences of considering not only the accuracy with which solar oscillations are measured, but also the effect of uncertainties in other aspects of the model computation and helioseismic analysis. 相似文献