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Magnetoatmospheric oscillations in sunspot umbrae

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dc.contributor.author Hasan, S. S
dc.date.accessioned 2008-09-11T15:53:48Z
dc.date.available 2008-09-11T15:53:48Z
dc.date.issued 1990-01
dc.identifier.citation Astrophysical Journal, Part 1 , Vol. 366, No. 1, pp. 328 - 339 en
dc.identifier.issn 0004-637X
dc.identifier.uri http://hdl.handle.net/2248/3545
dc.description.abstract The nature of umbral oscillations is investigated using an empirical model for the sunspot umbra, based on the model of Maltby et al. (1986). Approximating the sunspot as a thick flux tube of circular cross section, the axisymmetric normal modes of magnetoatmospheric waves were determined, and a diagnostic diagram was generated for different field strengths. The diagram shows the existence of 'avoided crossings' in the solution of magnetoatmospheric modes in a sunspot atmosphere. It was found that, for low values of the radial wavenumber k, corresponding to observed oscillations, a simple global classification is not possible. The oscillations in the low photosphere and below are of either fast or mixed type, but tend to acquire a slow or acoustic character above the temperature minimum. en
dc.language.iso en en
dc.publisher The American Astronomical Society en
dc.relation.uri http://dx.doi.org/10.1086/169566 en
dc.subject Solar atmosphere en
dc.subject Solar magnetic field en
dc.subject Solar oscillations en
dc.subject Sunspots en
dc.subject Atmospheric models en
dc.subject Kinetic energy en
dc.subject Linear equations en
dc.subject Magnetic field configurations en
dc.subject Photosphere en
dc.subject Solar temperature en
dc.title Magnetoatmospheric oscillations in sunspot umbrae en
dc.type Article en


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