Astrofísicas: Galaxias

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    OJ 287 and the predicted fade of 1998
    There were predictions that blazar OJ 287 should have faded in late 1997 or early 1998. The observational background for these predictions is the sudden fade of...
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    Old Globular Clusters Masquerading as Young in NGC 4365?
    High signal-to-noise ratio, low-resolution spectra have been obtained for 22 globular clusters (GCs) in NGC 4365. Some of these were selected as probable...
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    Old Main-Sequence Turnoff Photometry in the Small Magellanic Cloud. I. Constraints on the Star Formation History in Different Fields
    We present ground-based B- and R-band color-magnitude diagrams (CMDs) reaching the oldest main-sequence (MS) turnoffs with good photometric accuracy for 12...
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    Old Main-Sequence Turnoff Photometry in the Small Magellanic Cloud. II. Star Formation History and its Spatial Gradients
    We present a quantitative analysis of the star formation history (SFH) of 12 fields in the Small Magellanic Cloud (SMC) based on unprecedented deep [(B - R), R]...
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    Old Main-Sequence Turnoff Photometry in the SMC
    We present ground-based B and R-band color-magnitude diagrams (CMDs) of unprecedented depth for twelve fields in the Small Magellanic Cloud (SMC). They reach...
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    OMEGA - OSIRIS Mapping of Emission-line Galaxies in A901/2 - I. Survey description, data analysis, and star formation and AGN activity in the highest density regions
    We present an overview of and first results from the OMEGA (OSIRIS Mapping of Emission-line Galaxies in the multicluster system A901/2) survey. The ultimate...
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    On ageing star clusters using red supergiants independent of the fraction of interacting binary stars
    We use the Binary Population and Spectral Synthesis models to test the recent suggestion that red supergiants can provide an accurate age estimate of a coeval...
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    On an analytical framework for voids: their abundances, density profiles and local mass functions
    We present a general analytical procedure for computing the number density of voids with radius above a given value within the context of gravitational...
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    On biases in the predictions of stellar population synthesis models
    Sampling fluctuations in stellar populations give rise to dispersion in observables when a small number of sources contribute effectively to the observables...