@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"
}