Sandra Márcia Castro

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We review some of the scientific opportunities and technical challenges posed by the exploration of the large digital sky surveys, in the context of a Virtual Observatory (VO). The VO paradigm will profoundly change the way observational astronomy is done. Clustering analysis techniques can be used to discover samples of rare, unusual, or even previously(More)
Discovery of the cosmic reionization epoch would represent a significant milestone in cosmology. We present Keck spectroscopy of the quasar SDSS 1044–0125, at z = 5.73. The spectrum shows a dramatic increase in the optical depth at observed wavelengths λ >∼ 7550 Å, corresponding to zabs >∼ 5.2. Only a few small, narrow transmission regions are present in(More)
Using the IRAM interferometer we have detected J=4→3 and 5→4 CO line emission toward the radio quiet quasar PSS 2322+1944. At a redshift of zCO = 4.1199 this is the fourth and strongest detection of CO at z > 4. The velocity-integrated CO J=4→3 and J=5→4 line fluxes are 4.21± 0.40 and 3.74± 0.56 Jy kms−1, and the linewidth is ≈ 300 kms−1. The CO J=10→9 was(More)
We present accurate metallicity measurements for 121 damped Lyα systems at 0.5 < z < 5 including ≈ 50 new measurements from our recently published Echellette Spectrograph and Imager surveys. This dataset is analysed to determine the age-metallicity relation of neutral gas in the universe. Contrary to previous datasets this sample shows statistically(More)
Using the IRAM interferometer we have detected J = 4→3 and 5→4 CO line emission toward the radio quiet quasar PSS 2322+1944. At a redshift of zCO = 4.1199 this is the fourth and strongest detection of CO at z > 4. The velocity-integrated CO J = 4→3 and J = 5→4 line fluxes are 4.21 ± 0.40 and 3.74 ± 0.56 Jy km s−1, and the linewidth is ≈300 kms−1. The CO J =(More)
Studies of the cosmic gamma-ray bursts (GRBs) and their host galaxies are now starting to provide interesting or even unique new insights in observational cosmology. Observed GRB host galaxies have a median magnitude R ∼ 25 mag, and show a range of luminosities, morphologies, and star formation rates, with a median redshift z ∼ 1.0. They represent a new way(More)
We present sequential optical spectra of the afterglow of GRB 010222 obtained one day apart using the Low Resolution Imaging Spectrometer (LRIS) and the Echellette Spectrograph and Imager (ESI) on the Keck telescopes. Three lowionization absorption systems are spectroscopically identified at z1 = 1.47688, z2 = 1.15628, and z3 = 0.92747. The higher(More)
We report the first results of a program to study the internal kinematics of globular clusters in the outer halo of the Milky Way. Using the Keck telescope and High Resolution Echelle Spectrometer, we have measured precise radial velocities for 30 candidate red giants in the direction of Palomar 13, an object traditionally cataloged as a compact,(More)
1 Universidade Estadual de Feira de Santana, Av. Transnordestina, s/n, 40036-900, Feira de Santana, BA, Brasil e-mail: rguimara@eso.org 2 UPMC Paris 6, Institut d’Astrophysique de Paris, CNRS, 98bis boulevard Arago, 75014 Paris, France 3 Instituto Nacional de Pesquisas Espaciais INPE, Av. dos Astronautas 1758, 12227-010 S. J. dos Campos, SP, Brasil 4(More)
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