Journal ArticleDOI
On the rotation of the Sun
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In this paper, an asymptotic method is developed to estimate the rotational splitting of sectoral five-minute solar oscillations, which can be inverted to yield the variation with depth of the Sun's angular velocity near the equatorial plane.Abstract:
An asymptotic method is developed to estimate the rotational splitting of sectoral five-minute solar oscillations. Integral formulae are obtained which can be inverted to yield the variation with depth of the Sun's angular velocity near the equatorial plane. The result is a functional of smoothed data, and does not rely on a detailed theoretical model of the Sun. The method has been tested with artificial data (computed from a theoretical solar model) of a kind similar to some real solar data obtained recently by Duvall & Harvey (Nature, Lond. 310, 19 (1984)). The results are encouraging, for they reproduce at least the broadest feature of the somewhat arbitrary angular velocity with which the theoretical model was endowed. When applied to the real data, the method yields a result similar to that derived by Duvall et al. (Nature, Lond. 310, 22 (1984)) by another procedure.read more
Citations
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Journal ArticleDOI
Speed of sound in the solar interior
TL;DR: The sound speed of the solar interior is directly determinable on the basis of the frequencies of solar 5-min oscillations, irrespective of solar model, and relying only on a simple asymptotic description of the oscillations in terms of trapped acoustic waves as discussed by the authors.
Journal ArticleDOI
An asteroseismic signature of helium ionization
Günter Houdek,Douglas Gough +1 more
TL;DR: In this article, the authors investigate the influence of the ionization of helium on the low-degree acoustic oscillation frequencies in model solar-type stars and show how an analytic approximation to the variation of y leads to a simple representation of this oscillatory contribution to ∇ 2 ν which can be used to characterize the y variation, their intention being to use it as a seismic diagnostic of the helium abundance of the star.
Journal ArticleDOI
Global seismology of the Sun
TL;DR: In this article, the authors discuss some of the techniques used in helioseismic analyses and the results obtained using those techniques and briefly touch upon asteroseismology, the seismic study of stars other than the Sun, and discuss how seismic data of others stars are interpreted.
Journal ArticleDOI
Modeling the Subsurface Structure of Sunspots
Hamed Moradi,Charles S. Baldner,Aaron C. Birch,Douglas Braun,Robert H. Cameron,Thomas L. Duvall,Laurent Gizon,Deborah A. Haber,Shravan M. Hanasoge,Bradley W. Hindman,Jason Jackiewicz,Elena Khomenko,Rudolf Komm,Paul Rajaguru,Matthias Rempel,Michael Roth,Rolf Schlichenmaier,Hannah Schunker,Hendrik C. Spruit,Klaus G. Strassmeier,Michael Thompson,Michael Thompson,S. Zharkov,S. Zharkov +23 more
TL;DR: In this article, a critical review of the existing sunspot models and an overview of numerical methods employed to model wave propagation through model sunspots is provided, along with a helioseismic analysis of the sunspot in Active Region 9787 and address the serious inconsistencies uncovered by Gizon et al.
Journal ArticleDOI
Seismology of the sun.
TL;DR: The oscillation frequencies yield a helium abundance that is consistent with cosmology, but they reinforce the severity of the neutrino problem, which should soon provide an important standard by which to calibrate the theory of stellar evolution.
References
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Journal ArticleDOI
Smoothing by spline functions. II
TL;DR: In this paper, the authors generalize the results of [4] and modify the algorithm presented there to obtain a better rate of convergence, which is the same as in this paper.
Journal ArticleDOI
Internal rotation of the Sun
Thomas L. Duvall,W. A. Dziembowski,Philip R. Goode,Douglas Gough,J. W. Harvey,John Leibacher +5 more
TL;DR: In this article, the frequency difference between prograde and retrograde sectoral solar oscillations was analyzed to determine the rotation rate of the solar interior, assuming no latitudinal dependence, and the resulting solar gravitational quadrupole moment is J2 = (1.7 + or - 0.4) x 10 to the -7th and provides a negligible contribution to current planetary tests of general relativity.
Journal ArticleDOI
Rotational frequency splitting of solar oscillations
Thomas L. Duvall,J. W. Harvey +1 more
TL;DR: In this article, the authors observed the sectoral oscillations of the sun to determine frequency differences produced by rotation and found that most of the solar volume rotates at a rate close to that of the surface, but also that the energy generating core may rotate more rapidly than the surface.
Journal ArticleDOI
Rapid rotation of the solar interior
TL;DR: In this article, a measurement of the splitting of the discrete lines in the 5-min oscillations of the solar surface produced experimental evidence for the rapid internal rotation of the Sun, and the number of components into which the lines are split also allows unambiguous identification of 11 examples of each of the l = 0, l = 1 and l = 2 modes in the frequency range 2.40-3.85 mHz.
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