9 research outputs found
Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy
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
Aspectos neurocirĂşrgicos dos osteomas fronto-etmoidais: relato de 6 casos e revisĂŁo da literatura
SĂŁo relatados seis casos de osteomas fronto-etmoidais que provocaram complicações intracranianas ou orbitárias. Os casos sĂŁo divididos em dois grupos, dependendo dos sintomas observados, desde deformações cranio-faciais e exoftalmo atĂ© complicações mais graves como rinorrĂ©as, meningites, pneumocĂ©falos e mucoceles. Uma revisĂŁo da literatura mostra a importância destas lesões na patologia neurocirĂşrgica como causa de meningites recidivantes, rinorrĂ©as espontâneas e pneumocĂ©falos nĂŁo traumáticos. Uma análise crĂtica das tĂ©cnicas cirĂşrgicas propostas mostra que, por meio de craniotomia frontal, Ă© possĂvel obter resultado bom, tanto estĂ©tico como funcional