The results of a 2D numerical simulation of the rise of twisted magnetic flux tubes are sketched. The theoretical criterion for the minimum twist necessary to prevent the conversion of the tube into a pair of strong vortices is shown to be correct. The transition from a low-twist to a high-twist regime is exemplified. There is a sharp transition

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We study the global scaling-laws of 51 compact field galaxies with redshifts z = 0.2-1.3 and apparent magnitudes I

We present results of our search for free floating brown dwarfs in the Pleiades star cluster showing that the process of star formation does not stop at the substellar limit. A number of objects with masses below 70 Jupiter masses have been discovered by our group (Rebolo et al. 1995 Nature 377, 129; 1996, ApJ, 469, L53). The new extension of the

ISOPHOT is one of the instruments on board the Infrared Space Observatory (ISO), launched in November 1995 by the European Space Agency. ISOPHOT Interactive Analysis, PIA, is a scientific and calibration data analysis tool for ISOPHOT data reduction. The PIA software was designed both as a tool for use by the instrument team for calibration of the

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