Solar Polar Brightening and Radius at 100 and 230 GHz Observed by ALMA

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dc.contributor.authorSelhorst C.L.
dc.contributor.authorSimoes P.J.A.
dc.contributor.authorBrajsa R.
dc.contributor.authorValio A.
dc.contributor.authorDe Castro C.G.G.
dc.contributor.authorCosta J.E.R.
dc.contributor.authorMenezes F.
dc.contributor.authorRozelot J.P.
dc.contributor.authorHales A.S.
dc.contributor.authorIwai K.
dc.contributor.authorWhite S.
dc.date.accessioned2024-03-12T23:53:59Z
dc.date.available2024-03-12T23:53:59Z
dc.date.issued2019
dc.description.abstract© 2019. The American Astronomical Society. All rights reserved..Polar brightening of the Sun at radio frequencies has been studied for almost 50 years and yet a disagreement persists between solar atmospheric models and observations. Some observations reported brightening values much smaller than the expected values obtained from the models, with discrepancies being particularly large at millimeter wavelengths. New clues to calibrate the atmospheric models can be obtained with the advent of the Atacama Large Millimeter/submillimeter Array (ALMA) radio interferometer. In this work, we analyzed the lower limit of the polar brightening observed at 100 and 230 GHz by ALMA, during its Science Verification period, 2015 December 16-20. We find that the average polar intensity is higher than the disk intensity at 100 and 230 GHz, with larger brightness intensities at the south pole in eight of the nine maps analyzed. The observational results were compared with calculations of the millimetric limb brightening emission for two semi-empirical atmospheric models, FAL-C and SSC. Both models presented larger limb intensities than the average observed values. The intensities obtained with the SSC model were closer to the observations, with polar brightenings of 10.5% and 17.8% at 100 and 230 GHz, respectively. This discrepancy may be due to the presence of chromospheric features (like spicules) at regions close to the limb.
dc.description.issuenumber1
dc.description.volume871
dc.identifier.doi10.3847/1538-4357/aaf4f2
dc.identifier.issn1538-4357
dc.identifier.urihttps://dspace.mackenzie.br/handle/10899/35313
dc.relation.ispartofAstrophysical Journal
dc.rightsAcesso Aberto
dc.subject.otherlanguageSun: chromosphere
dc.subject.otherlanguageSun: general
dc.subject.otherlanguageSun: photosphere
dc.subject.otherlanguageSun: radio radiation
dc.titleSolar Polar Brightening and Radius at 100 and 230 GHz Observed by ALMA
dc.typeArtigo
local.scopus.citations22
local.scopus.eid2-s2.0-85062030886
local.scopus.updated2024-05-01
local.scopus.urlhttps://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85062030886&origin=inward
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