Following the discovery of the new X-ray transient XTE J1637-498 (Atel #1699), we obtained a short (nearly 1 ksec) observation using the Swift/XRT in PC mode on 2008-09-04 at 18:15 UT. We detected one relatively bright source within the ~6 arcminutes PCA error circle at a position of RA=16:37:02.995, Dec=-49:51:37 (J2000), with an estimated

El objetivo de la presente Tesis es contribuir al entendimiento de la estructura y evolución de galaxias, a través del estudio de las poblaciones estelares resueltas. En particular, estudiando la ``Pequeña Nube de Magallanes'', una de las dos únicas galaxias irregulares de la Vía Láctea. Situada a 60 kpc del sol es, después de la Gran Nube de

Context: Observations at 0.1 arcsec have revealed the existence of dark cores in the bright filaments of sunspot penumbrae. Expectations are high that such dark-cored filaments are the basic building blocks of the penumbra, but their nature remains unknown. Aims: We investigate the origin of dark cores in penumbral filaments and the surplus

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Magnetars are young neutron stars with very strong magnetic fields of the order of 1014-1015G. They are detected in our Galaxy either as soft γ-ray repeaters or anomalous X-ray pulsars. Soft γ-ray repeaters are a rare type of γ-ray transient sources that are occasionally detected as bursters in the high-energy sky. No optical counterpart to the γ