173 research outputs found

    Refractive index and extinction coefficient of vapor-deposited water ice in the UV-vis range

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    Laboratory astrophysics and astrochemistr

    Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

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    We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

    Desempenho de alevinos de jundiá alimentados com silagem de rejeito de peixe

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    O objetivo deste trabalho foi avaliar o desempenho zootécnico de alevinos de jundiá, alimentados com silagem de rejeitos de pescado, em substituição ao farelo de soja e à levedura de cana. Durante 35 dias, 375 alevinos de jundiá com peso inicial de 1,73±0,17 g, distribuídos em delineamento inteiramente casualizado, foram avaliados em cinco tratamentos e quatro repetições. Os tratamentos consistiram de inclusão de silagem de pescado a 0, 12,5, 25, 37,5 e 50%. Todos os parâmetros zootécnicos avaliados, exceto o fator de condição, mostraram que a substituição do farelo de soja e da levedura pela silagem de rejeito de pescado melhora o desempenho produtivo de alevinos de jundiá
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