Submitted by Automação e Estatística (sst@bczm.ufrn.br) on 2018-08-02T14:41:54Z No. of bitstreams: 1 JoseEdvaldoDeLimaJunior_DISSERT.pdf: 8648608 bytes, checksum: ac60121306bdbf8de8b282fdde78c614 (MD5) / Approved for entry into archive by clediane guedes (clediane@bczm.ufrn.br) on 2018-08-02T15:23:30Z (GMT) No. of bitstreams: 1 JoseEdvaldoDeLimaJunior_DISSERT.pdf: 8648608 bytes, checksum: ac60121306bdbf8de8b282fdde78c614 (MD5) / Made available in DSpace on 2018-08-02T15:23:30Z (GMT). No. of bitstreams: 1 JoseEdvaldoDeLimaJunior_DISSERT.pdf: 8648608 bytes, checksum: ac60121306bdbf8de8b282fdde78c614 (MD5) Previous issue date: 2015-12-21 / Este trabalho tem como foco principal a análise do infravermelho das 1916 estrelas gigantes vermelhas do catálogo de Pinsonneault. Para realizar tal análise nos utilizamos da avaliação do diagrama cor-cor como primeiro critério de seleção para a procura de estrelas com excesso de infravermelho, das quais 47 estrelas foram selecionadas, depois analisamos as distribuições espectrais de energia ou SED onde 29 estrelas foram selecionadas e para confirmação do excesso de infravermelho, passamos pela inspeção visual, onde das 29 estrelas apenas uma não apresentou contaminação por background de galáxias ou por uma estrela próxima. Na inspeção visual, e nas SEDS analisamos o excesso nas bandas W1, W2 e principalmente nas bandas W3 e W4 do satélite WISE. Por fim calculamos a temperatura dessa poeira em aproximadamente 200K. / This work has focused primarily on the analysis of infrared of 1916 red giant stars Pinsonneault catalog. To perform this analysis we use the evaluation of the color-color diagram as a first selection criterion looking for stars with infrared excess, of which 47 were selected stars, then we analyze the spectral energy distributions or SED where 29 stars were selected and infrared excess of confirmation, We passed the visual inspection, where the 29 stars one, the KIC9728845 star, showed no contamination by background galaxies or a nearby star. On visual inspection, and the SEDS analyzed over the bands W1, W2 and W3 mainly by bands and bands W3 and W4 satellite WISE. Finally we calculate the tempertura this dust at about 200K.

We present the final results from a targeted search for brown dwarfs with unusual near-infrared colors. From a positional cross-match of the Sloan Digital Sky Survey (SDSS), 2-Micron All-Sky Survey (2MASS), and Wide-Field Infrared Survey Explorer (WISE) catalogs, we have identified 144 candidate peculiar L and T dwarfs. Spectroscopy confirms that 20 of the objects are peculiar or are candidate binaries. Of the 420 objects in our full sample 9 are young (less than or similar to 200 Myr; 2.1%) and another 8 (1.9%) are unusually red, with no signatures of youth. With a spectroscopic J-K-s color of 2.58 +/- 0.11 mag, one of the new objects, the L6 dwarf 2MASS J03530419 +0418193, is among the reddest field dwarfs currently known and is one of the reddest objects with no signatures of youth known to date. We have also discovered another potentially very-low-gravity object, the L1 dwarf 2MASS J00133470+1109403, and independently identified the young L7 dwarf 2MASS J00440332+0228112, which was first reported by Schneider and collaborators. Our results confirm that signatures of low gravity are no longer discernible in low to moderate resolution spectra of objects older than similar to 200 Myr. The 1.9% of unusually red L dwarfs that do not show other signatures of youth could be slightly older, up to similar to 400 Myr. In this case a red J - K-s color may be more diagnostic of moderate youth than individual spectral features. However, its is also possible that these objects are relatively metal-rich, and thus have enhanced atmospheric dust content.