scholarly journals What can we Learn from Oscillation Studies about Irradiance and Radius Changes?

1994 ◽  
Vol 143 ◽  
pp. 252-263 ◽  
Author(s):  
Douglas Gough
Keyword(s):  
Internal Structure ◽  
The Sun ◽  
Solar Oscillations ◽  
Thermal Modulation

Dynamical and thermal modulation of the internal structure of the Sun can be manifest at the surface as changes in irradiance and radius. The relative magnitudes of these changes could provide a diagnostic of at least the location of the primary modulation, if only the mechanism were known. Variations of the frequencies of solar oscillations offer additional potentially valuable diagnostics, but unfortunately at present the mechanisms causing those variations and their relation to the structural and irradiance changes are not yet understood. In this lecture I shall review some of the theoretical conjectures that have been put forward to explain the observations.

scholarly journals The Internal Structure of the Sun and Solar Type Stars

1976 ◽  
Vol 71 ◽  
pp. 453-466 ◽  
Author(s):  
IAN W. Roxburgh
Keyword(s):  
Internal Structure ◽  
Solar Neutrino ◽  
Convective Zone ◽  
The Sun ◽  
Solar Oscillations ◽  
Solar Constant ◽  
Solar Neutrino Problem ◽  
Solar Type

Our understanding of the internal structure of the Sun and solar type stars has been undermined by recent observations. In this paper we consider some of the puzzles and possible resolutions; the solar neutrino problem, lithium and beryllium abundance, rotation and calcium emission, variation of the solar constant, solar oscillations and the solar convective zone. The picture that emerges is one of confusion, and so it should be since we have no idea of what is going on inside the Sun and a fortiori of what is going on inside other stars.

scholarly journals Helioseismic Investigation of Solar Internal Structure

1990 ◽  
Vol 121 ◽  
pp. 305-326
Author(s):  
Jørgen Christensen-Dalsgaard
Keyword(s):  
Internal Structure ◽  
The Sun ◽  
Solar Oscillation ◽  
Solar Oscillations ◽  
Oscillation Frequencies

AbstractThe solar oscillation frequencies provide our only means of obtaining detailed information about conditions inside the Sun. Here I give a brief overview of the relevant properties of solar models and solar oscillations, and present examples of the dependence of the oscillation frequencies on the structure of the model. Furthermore I discuss some results obtained so far from analysis of observed frequencies.

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 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 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.

Solar neutrinos and solar oscillations

1994 ◽  
Vol 346 (1678) ◽  
pp. 37-49 ◽  
Keyword(s):  
Solar Neutrino ◽  
Particle Physics ◽  
Sound Speed ◽  
Solar Neutrinos ◽  
Diagnostic Information ◽  
The Sun ◽  
Solar Oscillations ◽  
Thermonuclear Reactions ◽  
Neutrino Production ◽  
Classical Models

For solar neutrino measurements to contribute directly to particle physics it is essential that we know the structure of the Sun. Only then can we be sure both of the conditions under which the neutrinos are produced and of the state of the material through which they must pass before arriving at the detectors on Earth. Solar oscillations play at least one, and possibly two important roles: firstly, as passive carriers of information about density and sound speed, they provide important diagnostic information which has been used to set quite stringent constraints on the structure of the Sun’s interior; secondly, as active participants in the dynamics of the solar core, it is not out of the question that they induce motion that influences substantially the rates of the various thermonuclear reactions that em it the neutrinos. The basic processes of seismic inference will be discussed briefly, followed by a summary of those inferences that have a bearing on neutrino production. Finally, some of the uncertainties in our understanding of the Sun’s interior will be aired, to restrain the temptation to accept too hastily the details of the simple hydrostatic classical models of the Sun.

scholarly journals Solar activity and solar oscillations

1997 ◽  
Vol 181 ◽  
pp. 277-285
Author(s):  
Y. Elsworth
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Radio Emission ◽  
Surface Temperature ◽  
The Sun ◽  
Solar Oscillations ◽  
Thermal Component ◽  
X Ray ◽  
Convective Flows ◽  
Wide Range

Helioseismology provides us with the tools to probe solar activity. So that we can consider how the solar oscillations are influenced by that activity, we first consider the phenomena that we associate with the active Sun. The surface of the Sun is not quiet but shows evidence of convection on a wide range of scales from a few hundred kilometres through to several tens-of-thousands of kilometres. The surface temperature shows signs of the convection structures with the temperature in the bright granules being some 100 K to 200 K hotter than the surrounding dark lanes. Sunspots, which are regions of high magnetic field that suppress convective flows, are clearly visible to even quite crude observations. They are several tens-of-thousands of kilometres in diameter and about 2000 K cooler than their surroundings. Ultraviolet and X-ray pictures from satellites show that the higher layers of the solar atmosphere are very non-uniform with bright regions of high activity. Contemporaneous magnetograms show that these regions are associated with sunspots. Flares - regions of magnetic reconnections - are seen at all wavelengths from X-ray through the visible to radio. They are the non-thermal component of the radio emission of the Sun. There are many other indicators of activity on the Sun.

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.

scholarly journals Introduction

1995 ◽  
Vol 10 ◽  
pp. 319-320
Author(s):  
W. Däppen
Keyword(s):  
Spherical Harmonics ◽  
Solar Rotation ◽  
Solar Neutrinos ◽  
The Sun ◽  
Solar Oscillations ◽  
Good Information ◽  
Solar Neutrino Problem ◽  
Oscillation Frequencies ◽  
Very High ◽  
Better Than

Since the early 1960s the surface of the Sun has been know to be in a regular pulsating motion with periods of about 5 minutes. While at the beginning various explanations were offered, only in the 1970s it was recognized that these so-called solar oscillations are manifestations of global motions of the Sun about its equilibrium. Helioseismology is the name of the branch of astrophysics that deals with deciphering these data, that cover the whole range of spherical harmonics from l = 0 (radial) to very high angular order (above l = 1000). Thanks to observational data of superb quality (each of the oscillation frequencies is measured accurately to better than one part in ten thousand), our knowledge of the Sun has leap-frogged in the last 20 years. For instance, we now know the run of temperature inside the Sun, or have good information about the internal solar rotation. In the solar neutrino problem the data from solar oscillations have become a compulsory testing stone for any model proposed to explain the discrepancy between observed and theoretically predicted solar neutrinos.

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