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@Article{VilasBoasAbra:2000:NHToSo,
               author = "Vilas Boas, Jos{\'e} Williams dos Santos and Abraham, Zulema",
                title = "NH3(1,1)survey toward southern hemisphere HII regions. I",
              journal = "Astronomy \& Astrophysics",
                 year = "2000",
               volume = "355",
               number = "3",
                pages = "1115--1121",
                month = "Mar.",
             keywords = "RADIASTRONOMIA, abund{\^a}ncias, nuvens de mol{\'e}culas, 
                         linhas, galaxias, am{\^o}nia, abundance, clouds, molecules 
                         clouds, lines, galaxies, ammonia.",
             abstract = "The (J,K)=(1,1)metastable ammonia line was searched for in the 
                         direction of more than one hundred southern HII regions located 
                         between 270 degrees and 15 degrees in galactic longitude, 
                         resulting in new detections toward 21 of them. Ammonia detection 
                         rate was about 30 towards all directions except in the longitude 
                         interval 270 degrees-290 degrees where no ammonia lines were found 
                         in the 15 selected HII regions. A high detection rate (greater 
                         than or equal to 0.6)was observed toward positions where IRAS 
                         point sources with color indices of ultra-compact HII regions were 
                         in the beam of the telescope. An anticorrelation between the 
                         number of detected NH3 sources and the distance to the Galactic 
                         Center was found, compatible with the observed gradient in N 
                         abundance. From the Value of this gradient and the detection rate 
                         of ammonia lines toward HII regions, it is inferred that the 
                         number of ammonia sources must be proportional to the inverse of 
                         the column density of the molecular cloud.",
                 issn = "0004-6361 and 1432-0746",
                label = "9532",
           targetfile = "8951.pdf",
        urlaccessdate = "18 jan. 2021"
}


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