Las binarias compactas son sistemas formados por un objeto compacto (agujero negro (AN), estrella de neutrones (EN) o enana blanca) que acrece gracias a la masa procedente de una estrella compañera (también llamada donante). De manera general, la transferencia se produce por medio de un disco de acreción. A las binarias compactas que albergan EN o

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The calculation of solar absolute fluxes in the near-UV is revisited, discussing in some detail recent updates in theoretical calculations of bound free opacity from metals. Modest changes in the abundances of elements such as Mg and iron-peak elements have a significant impact on atmospheric structure, and therefore self-consistent calculations

We report the discovery of a previously unseen X-ray source detected in a 5ks Chandra/ACIS observation starting on 2008-11-27.72 UT as part of our ongoing Chandra/HST M31 transient program. Its coordinates (subject to the standard boresight correction) are RA(J2000) 00:42:45.96, Dec(J2000) +41:10:36.60, with centroiding errors of 0.18" and 0.21"

We present an astrometric catalogue of positions and proper motions derived from the Carte du Ciel plates of the San Fernando zone, which has a mean epoch 1901.4 and a limiting magnitude V 15. Digitization has been made using a conventional flatbed scanner. Special techniques have been developed to handle the combination of plate material and the