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Astronomische Nachrichten
Article . 2012 . Peer-reviewed
License: Wiley Online Library User Agreement
Data sources: Crossref
https://dx.doi.org/10.48550/ar...
Article . 2012
License: arXiv Non-Exclusive Distribution
Data sources: Datacite
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Asteroseismology and magnetic cycles

Authors: Santos, A. R. G.; Cunha, M. S.; Lima, J. J. G.;

Asteroseismology and magnetic cycles

Abstract

AbstractSmall cyclic variations in the frequencies of acoustic modes are expected to be a common phenomenon in solar‐like pulsators, as a result of stellar magnetic activity cycles. The frequency variations observed throughout the solar and stellar cycles contain information about structural changes that take place inside the stars as well as about variations in magnetic field structure and intensity. The task of inferring and disentangling that information is, however, not a trivial one. In the sun and solar‐like pulsators, the direct effect of the magnetic field on the oscillations might be significantly important in regions of strong magnetic field (such as solar/stellar spots), where the Lorentz force can be comparable to the gas‐pressure gradient. Our aim is to determine the sun‐/starspot effect on the oscillation frequencies and attempt to understand if this effect contributes strongly to the frequency changes observed along the magnetic cycle. The total contribution of the spots to the frequency shifts results from a combination of direct and indirect effects of the magnetic field on the oscillations. In this first work we considered only the indirect effect associated with changes in the stratification within the starspot. Based on the solution of the wave equation and the variational principal we estimated the impact of these stratification changes on the oscillation frequencies of global modes in the sun and found that the induced frequency shifts are about two orders of magnitude smaller than the frequency shifts observed over the solar cycle (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Keywords

Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, Solar and Stellar Astrophysics (astro-ph.SR)

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
4
Average
Average
Average
Green
bronze