4,485 research outputs found
U B V R I Photometry of Stellar Structures throughout the Disk of the Barred Galaxy NGC 3367
We report new detailed surface U, B, V, R, and I photometry of 81 stellar
structures in the disk of the barred galaxy NGC 3367. The images show many
different structures indicating that star formation is going on in the most
part of the disk. NGC 3367 is known to have a very high concentration of
molecular gas distribution in the central regions of the galaxy and bipolar
synchrotron emission from the nucleus with two lobes (at 6 kpc) forming a
triple structure similar to a radio galaxy. We have determined the U, B, V, R,
and I magnitudes and U - B, B - V, U - V, and V - I colors for the central
region (nucleus), a region which includes supernovae 2003 AA, and 79 star
associations throughout NGC 3367. Estimation of ages of star associations is
very difficult due to several factors, among them: filling factor, metallicity,
spatial distribution of each structure and the fact that we estimated the
magnitudes with a circular aperture of 16 pixels in diameter, equivalent to
kpc. However, if the colors derived for NGC 3367 were similar to
the colors expected of star clusters with theoretical evolutionary star tracks
developed for the LMC and had a similar metallicity, NGC 3367 show 51 percent
of the observed structures with age type SWB I (few tens of Myrs), with seven
sources outside the bright surface brightness visible disk of NGC 3367.Comment: Accepted for publication (abr 2007) in The Astronomical Journal (July
2007 issue
Equation of state and transport processes in self--similar spheres
We study the effect of transport processes (diffusion and free--streaming) on
a collapsing spherically symmetric distribution of matter in a self--similar
space--time. A very simple solution shows interesting features when it is
matched with the Vaidya exterior solution. In the mixed case (diffusion and
free--streaming), we find a barotropic equation of state in the stationary
regime. In the diffusion approximation the gravitational potential at the
surface is always constant; if we perturb the stationary state, the system is
very stable, recovering the barotropic equation of state as time progresses. In
the free--streaming case the self--similar evolution is stationary but with a
non--barotropic equation of state.Comment: 9 pages, 2 figure
Perspectivas da mandiocultura como alternativa para o desenvolvimento sustentável do Amazonas.
Informações técnicas sobre a vantagem do cultivo da mandioca para o desenvolvimento sustentável no Amazonas (Brasil)
Cultivar BRS Purus: nova alternativa de mandioca para terra firme no Amazonas.
Mandioca cultivar BRS Purus: origem, adaptação, características botânica e agronômica, recomendações técnicas e produtividade, em Manaus-AM.bitstream/CPAA-2009-09/4507/1/Folder_Mandioca.pd
Self-similar and charged spheres in the diffusion approximation
We study spherical, charged and self--similar distributions of matter in the
diffusion approximation. We propose a simple, dynamic but physically meaningful
solution. For such a solution we obtain a model in which the distribution
becomes static and changes to dust. The collapse is halted with damped mass
oscillations about the absolute value of the total charge.Comment: 15 pages, 7 figure
Avaliação das condições de salinidade, drenagem e fertilidade e alterações químicas ocorridas em areia quartzozas apos cinco anos sob irrigação localizada.
Este trabalho foi conduzido em uma área de areia quartzoza da Fazenda Boa Esperança, em Petrolina-Pe, cultivada c om videira e mangueira. Avaliou-se o efeito d a irrigação e da adubação, aplicadas durante cinco anos, sobre algumas características químicas do solo e aparecimento de lençol freático. O sistema de irrigação utilizado foi micro-aspersão. Amostragem do solo foi feita em 34 pontos da área cultivada, onde estão localizados os poços, para observação do nível do lençol freático. Os resultados analíticos mostraram que houve um aumento da CE das bases trocáveis e do fósforo "disponível" e o aparecimento do lençol freático, na área da videira
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