FIVE-MINUTE OSCILLATION POWER WITHIN MAGNETIC ELEMENTS IN THE SOLAR ATMOSPHERE

2.50
Hdl Handle:
http://hdl.handle.net/2436/621036
Title:
FIVE-MINUTE OSCILLATION POWER WITHIN MAGNETIC ELEMENTS IN THE SOLAR ATMOSPHERE
Authors:
Jain, Rekha; Gascoyne, Andrew; Hindman, Bradley W.; Greer, Benjamin
Abstract:
It has long been known that magnetic plage and sunspots are regions in which the power of acoustic waves is reduced within the photospheric layers. Recent observations now suggest that this suppression of power extends into the low chromosphere and is also present in small magnetic elements far from active regions. In this paper we investigate the observed power suppression in plage and magnetic elements, by modeling each as a collection of vertically aligned magnetic fibrils and presuming that the velocity within each fibril is the response to buffeting by incident p modes in the surrounding field-free atmosphere. We restrict our attention to modeling observations made near the solar disk center, where the line-of-sight velocity is nearly vertical and hence, only the longitudinal component of the motion within the fibril contributes. Therefore, we only consider the excitation of axisymmetric sausage waves and ignore kink oscillations as their motions are primarily horizontal. We compare the vertical motion within the fibril with the vertical motion of the incident p mode by constructing the ratio of their powers. In agreement with observational measurements we find that the total power is suppressed within strong magnetic elements for frequencies below the acoustic cut-off frequency. However, further physical effects need to be examined for understanding the observed power ratios for stronger magnetic field strengths and higher frequencies. We also find that the magnitude of the power deficit increases with the height above the photosphere at which the measurement is made. Furthermore, we argue that the area of the solar disk over which the power suppression extends increases as a function of height.
Citation:
FIVE-MINUTE OSCILLATION POWER WITHIN MAGNETIC ELEMENTS IN THE SOLAR ATMOSPHERE 2014, 796 (2):72 The Astrophysical Journal
Publisher:
IOP Publishing
Journal:
The Astrophysical Journal
Issue Date:
6-Nov-2014
URI:
http://hdl.handle.net/2436/621036
DOI:
10.1088/0004-637X/796/2/72
Additional Links:
http://stacks.iop.org/0004-637X/796/i=2/a=72?key=crossref.e9b4601fbece389f52e18b5695ccbaf6
Type:
Article
Language:
en
ISSN:
1538-4357
Sponsors:
STFC (UK) and NASA grants NNX09AB04G, NNX14AC05G, and NNX14AG05G
Appears in Collections:
FSE

Full metadata record

DC FieldValue Language
dc.contributor.authorJain, Rekhaen
dc.contributor.authorGascoyne, Andrewen
dc.contributor.authorHindman, Bradley W.en
dc.contributor.authorGreer, Benjaminen
dc.date.accessioned2018-01-17T10:30:14Z-
dc.date.available2018-01-17T10:30:14Z-
dc.date.issued2014-11-06-
dc.identifier.citationFIVE-MINUTE OSCILLATION POWER WITHIN MAGNETIC ELEMENTS IN THE SOLAR ATMOSPHERE 2014, 796 (2):72 The Astrophysical Journalen
dc.identifier.issn1538-4357-
dc.identifier.doi10.1088/0004-637X/796/2/72-
dc.identifier.urihttp://hdl.handle.net/2436/621036-
dc.description.abstractIt has long been known that magnetic plage and sunspots are regions in which the power of acoustic waves is reduced within the photospheric layers. Recent observations now suggest that this suppression of power extends into the low chromosphere and is also present in small magnetic elements far from active regions. In this paper we investigate the observed power suppression in plage and magnetic elements, by modeling each as a collection of vertically aligned magnetic fibrils and presuming that the velocity within each fibril is the response to buffeting by incident p modes in the surrounding field-free atmosphere. We restrict our attention to modeling observations made near the solar disk center, where the line-of-sight velocity is nearly vertical and hence, only the longitudinal component of the motion within the fibril contributes. Therefore, we only consider the excitation of axisymmetric sausage waves and ignore kink oscillations as their motions are primarily horizontal. We compare the vertical motion within the fibril with the vertical motion of the incident p mode by constructing the ratio of their powers. In agreement with observational measurements we find that the total power is suppressed within strong magnetic elements for frequencies below the acoustic cut-off frequency. However, further physical effects need to be examined for understanding the observed power ratios for stronger magnetic field strengths and higher frequencies. We also find that the magnitude of the power deficit increases with the height above the photosphere at which the measurement is made. Furthermore, we argue that the area of the solar disk over which the power suppression extends increases as a function of height.en
dc.description.sponsorshipSTFC (UK) and NASA grants NNX09AB04G, NNX14AC05G, and NNX14AG05Gen
dc.language.isoenen
dc.publisherIOP Publishingen
dc.relation.urlhttp://stacks.iop.org/0004-637X/796/i=2/a=72?key=crossref.e9b4601fbece389f52e18b5695ccbaf6en
dc.rightsArchived with thanks to The Astrophysical Journalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/*
dc.subjectLine: formationen
dc.subjectmagnetohydrodynamics (MHD)en
dc.subjectSun: helioseismologyen
dc.subjectSun: magnetic fieldsen
dc.subjectSun: oscillationsen
dc.subjectSun: photosphereen
dc.subjectwavesen
dc.titleFIVE-MINUTE OSCILLATION POWER WITHIN MAGNETIC ELEMENTS IN THE SOLAR ATMOSPHEREen
dc.typeArticleen
dc.identifier.journalThe Astrophysical Journalen
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