scholarly journals Inverse problem: acoustic potential vs acoustic length

1988 ◽  
Vol 123 ◽  
pp. 133-136
Author(s):  
Hiromoto Shibahashi
Keyword(s):  
Inverse Problem ◽  
Integral Equation ◽  
Sound Velocity ◽  
Internal Structure ◽  
Asymptotic Method ◽  
The Sun ◽  
Quantization Rule ◽  
Rule Based ◽  
Deep Interior

By using the quantization rule based on the WKB asymptotic method, we present an integral equation to infer the form of the acoustic potential of a fixed ℓ as a function of the acoustic length. Since we analyze the acoustic potential itself by taking account of some factors other than the sound velocity and we can analyze the radial modes by this scheme as well as nonradial modes, this method improves the accuracy and effectiveness of the inverse problem to infer the internal structure of the Sun, in particular, the deep interior of the Sun.

scholarly journals White Dwarf Seismology: Inverse Problem of g-Mode Oscillations

1988 ◽  
Vol 108 ◽  
pp. 86-87
Author(s):  
Hiromoto Shibahashi ◽  
Takashi Sekii ◽  
Steven Kawaler
Keyword(s):  
Inverse Problem ◽  
Internal Structure ◽  
White Dwarf ◽  
White Dwarfs ◽  
Research Field ◽  
The Sun ◽  
Pulsating Stars ◽  
Low Degree ◽  
Physical Quantities ◽  
Light Variability

Since light variability in white dwarfs was first discovered twenty years ago, eighteen DA white dwarfs, several pulsating DB white dwarfs, and hotter pre-white dwarfs have so far been found to be pulsating variables. The most conspicuous characteristics of pulsations in these stars are that they seem to consist of multiple g-modes of nonradial oscillations. Attention should be paid to multiplicity of modes. Stimulated by the success of helioseimology, a research field called ‘asteroseismology’, in which we may probe the internal structure of stars by means of observations of their oscillations, is going to develop. How well such a seismological approach succeeds is dependent on how many modes are observed in each of stars. Since the number of modes of an individual pulsating white dwarf is larger than those of other types of pulsating stars but for the Sun, the seismological study may be the most promising as to the white dwarfs. In fact, by applying the asymptotic relations among eigenfrequencies of high order g-modes with low degree, the degreel, and the radial ordern, Kawaler(1987a,b,c) succeeded to get some constraints on the physical quantities of some of pulsating white dwarfs.

scholarly journals Nonradial and radial oscillations observed in non-emission line OB dwarfs and giants

1986 ◽  
Vol 7 ◽  
pp. 255-263
Author(s):  
Dietrich Baade
Keyword(s):  
Mass Loss ◽  
Emission Line ◽  
Internal Structure ◽  
Fundamental Problem ◽  
Spectral Lines ◽  
Driving Mechanism ◽  
The Sun ◽  
Ob Stars ◽  
Pulsating Stars ◽  
Reconnaissance Surveys

Only a decade ago, this talk could have concerned only the β Cephei stars which however populate a much more precisely defined strip in the Hertzsprung-Russel diagram (MED). But recent reconnaissance surveys (Smith 1977; Smith and Penrod 1984; Waelkens and Rufener 1985; Baade, in preparation) show that perhaps only one, if any, sizeable region of the upper HRD is devoid of nonradially pulsating stars. The identification of the driving mechanism is still pending (cf. the parallel talk by Osaki), and apparently our knowledge about the internal structure of OB stars is incomplete. But, turning that argument around, it also is indicative of how much may be learned about OB stars from and through the solution of that fundamental problem. This seismologial potential, the ubiquity of the phenomenon, and the effect, as suggested by recent observations of some stars, of the pulsations on the mass loss of OB stars make the oscillations of OB stars one of the most important problems of current astrophysics. On the observational side, rotationally broadened spectral lines, large amplitudes, comparatively long periods, and high luminosities permit information to be gathered which otherwise is accessible only for the sun.

scholarly journals Potential energy stored by planets and grand minima events

2011 ◽  
Vol 7 (S286) ◽  
pp. 410-413
Author(s):  
Rodolfo G. Cionco
Keyword(s):  
Solar Cycle ◽  
Solar System ◽  
Potential Energy ◽  
Internal Structure ◽  
Temporal Evolution ◽  
Maunder Minimum ◽  
The Sun ◽  
Dalton Minimum ◽  
Putative Mechanism ◽  
Grand Minima

AbstractRecently, Wolff & Patrone (2010), have developed a simple but very interesting model by which the movement of the Sun around the barycentre of the Solar system could create potential energy that could be released by flows pre-existing inside the Sun. The authors claim that it is the first mechanism showing how planetary movements can modify internal structure in the Sun that can be related to solar cycle. In this work we point out limitations of mentioned mechanism (which is based on interchange arguments), which could be inapplicable to a real star. Then, we calculate the temporal evolution of potential energy stored in zones of Sun's interior in which the potential energy could be most efficiently stored taking into account detailed barycentric Sun dynamics. We show strong variations of potential energy related to Maunder Minimum, Dalton Minimum and the maximum of Cycle 22, around 1990. We discuss briefly possible implications of this putative mechanism to solar cycle specially Grand Minima events.

scholarly journals Integral equation methods for the inverse problem with discontinuous wave speed

1996 ◽  
Vol 37 (7) ◽  
pp. 3218-3245 ◽  
Author(s):  
Tuncay Aktosun ◽  
Martin Klaus ◽  
Cornelis van der Mee
Keyword(s):  
Inverse Problem ◽  
Integral Equation ◽  
Wave Speed ◽  
Discontinuous Wave ◽  
Integral Equation Methods

On the investigation of the internal structure of the sun by means of neutrino radiation studies

1968 ◽  
Vol 46 (10) ◽  
pp. S491-S493
Author(s):  
V. A. Dergachov ◽  
G. E. Kocharov
Keyword(s):  
Energy Spectrum ◽  
Experimental Determination ◽  
Internal Structure ◽  
Solar Neutrino ◽  
Gravitational Constant ◽  
Neutrino Flux ◽  
The Sun ◽  
Neutrino Radiation ◽  
Solar Neutrino Flux

We consider the possibilities of investigating the internal structure of the sun using the energy spectrum and the intensity of its neutrino radiation. The experimental determination of the solar neutrino flux will permit us to obtain values for some parameters which are important for the theory of the internal structure of the sun (e.g. the time for evolution and the concentrations of various isotopes in the interior). It is also possible to decide whether or not the gravitational constant varies with time.

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