We consider the coupling between massive and spinning particles and three dimensional gravity. This allows us to construct geometric operators (distances between particles) as Dirac observables. We quantize the system à la loop quantum gravity: we give a description of the kinematical Hilbert space and construct the associated spin-foam model. We

We present some results of a CFHT adaptive optics search for companions to nearby dwarfs. We identify 21 new components in solar neighbourhood systems, of which 13 were found while surveying a volume-limited sample of M dwarfs within 12 pc. We are obtaining complete observations for this subsample, to derive unbiased multiplicity statistics for the

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Presentamos y discutimos en esta tesis un nuevo y original algoritmo - el Método Integral Implícito (MII) - para la solución numérica de la ecuación de transporte radiativo (TR) en condiciones físicas similares a las de las atmósferas estelares. En la primera parte se presenta el proceso de TR en términos operativos actuales: utilización de la

The structure and kinematics of the bipolar nebula Mz 3 have been investigated by means of HST, CTIO and ESO images and spectra. At least four distinct outflows have been identified which, from the inside to the outside, are the following: a pair of bright bipolar lobes, two opposite highly collimated column-shaped outflows, a conical system of