What determines the radio polar brightening?

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dc.contributor.authorSelhorst C.L.
dc.contributor.authorSilva A.V.R.
dc.contributor.authorCosta J.E.R.
dc.date.accessioned2024-03-13T01:43:53Z
dc.date.available2024-03-13T01:43:53Z
dc.date.issued2005
dc.description.abstractIn order to explain the bright patches of emission near the poles of 17 GHz solar maps, we have applied a previously developed atmospheric model based on radio observations. This 2-D model, which includes spicules, yields results in good agreement with brightness temperature values at the disk center, radius, and limb brightening 17 GHz observations at equatorial and intermediate regions. Nevertheless, the intensity of discrete bright patches observed near the poles in 17 GHz maps (as bright as 40% over the quiet Sun), can only be explained by holes in the spicule forest. These regions without spicules probably reflect the presence of polar faculae, which inhibit the appearance of spicules. Moreover, the absence of spicules over faculae explains the anti-correlation between the mean polar limb brightening and the solar cycle, because the polar faculae are known be anti-correlated with the solar cycle. Results from the model with spicule-less regions showed that: 1) for bare regions of the same size (5°), the limb brightening increases with the pole proximity; 2) larger regions yield more intense limb brightening; 3) the average height of the spicules greatly influences the solar radius; 4) the maximum excess brightness temperature of 40% is in very good agreement with the polar limb observations above bright patches. © ESO 2005.
dc.description.firstpage367
dc.description.issuenumber1
dc.description.lastpage371
dc.description.volume440
dc.identifier.doi10.1051/0004-6361:20053083
dc.identifier.issn0004-6361
dc.identifier.urihttps://dspace.mackenzie.br/handle/10899/37866
dc.relation.ispartofAstronomy and Astrophysics
dc.rightsAcesso Aberto
dc.subject.otherlanguageSun: atmosphere
dc.subject.otherlanguageSun: faculae, plages
dc.subject.otherlanguageSun: fundamental parameters
dc.subject.otherlanguageSun: radio radiation
dc.titleWhat determines the radio polar brightening?
dc.typeArtigo
local.scopus.citations10
local.scopus.eid2-s2.0-24944457269
local.scopus.subjectSun: atmosphere
local.scopus.subjectSun: faculae, plages
local.scopus.subjectSun: fundamental parameters
local.scopus.subjectSun: radio radiation
local.scopus.updated2024-05-01
local.scopus.urlhttps://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=24944457269&origin=inward
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