@Article{SelhorstSBVGCFRHIW:2019:SoPoBr,
author = "Selhorst, Caius L. and Sim{\~o}es, Paulo J. A. and Brajsa, Roman
and Valio, Adriana and Gim{\'e}nez de Castro, Carlos Guillermo
and Costa, Joaquim Eduardo Rezende and Fabian, Menezes and
Rozelot, Jean Pierre and Hales, Antonio S. and Iwai, Kazumasa and
White, Stephen",
affiliation = "{Universidade Cruzeiro do Sul} and {University of Glasgow} and
{University of Zagreb} and {Universidade Presbiteriana Mackenzie}
and {Universidade Presbiteriana Mackenzie} and {Instituto Nacional
de Pesquisas Espaciais (INPE)} and {Universidade Presbiteriana
Mackenzie} and {Universit{\'e} C{\^o}te d’Azur} and {Joint ALMA
Observatory} and {Nagoya University} and {Air Force Research
Laboratory}",
title = "Solar polar brightening and radius at 100 and 230 GHz observed by
ALMA",
journal = "Astrophysical Journal",
year = "2019",
volume = "871",
number = "1",
pages = "e45",
month = "Jan.",
keywords = "Sun: chromosphere, Sun: general, Sun: photosphere, Sun: radio
radiation.",
abstract = "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.",
doi = "10.3847/1538-4357/aaf4f2",
url = "http://dx.doi.org/10.3847/1538-4357/aaf4f2",
issn = "0004-637X and 1538-4357",
language = "en",
targetfile = "selhorst_solar.pdf",
urlaccessdate = "27 abr. 2024"
}