We find a strong correlation between the optical outburst amplitude and orbital period for the soft X-ray transient sources with orbital periods less than 1 d. By fitting the observed values for eight X-ray transients, we determine an empirical relation that can be used to predict the orbital period of an X-ray transient given only its outburst

Within the classical Eulerian theory of gravitational instability, and in an Omega = 1 universe, we introduce a method for obtaining iterative solutions for the density contrast and peculiar velocity that can be extended to any order of approximation in the quasilinear regime. We compute the solution up to the fourth order (E4) and establish a

The huge photometric databases that are being created for stars in the Magellanic Clouds and in Local Group galaxies not only allow a detailed study of the star formation history of these systems but also provide important information on stellar evolutionary theory. Two low-level features above the red clump in the LMC color-magnitude diagram (CMD)

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The main objective of the GOLF Experiment (Global Oscillations at Low Frequencies) on-board the SOHO (Solar and Heliospheric Observatory) space mission is the quantitative knowledge of the internal structure of the Sun by measuring the spectrum of its global oscillations in a wide frequency range (30 nHz to 6 mHz). There is special interest in

We present a library of Utrecht echelle spectrograph (UES) observations of a sample of F, G, K and M field dwarf stars covering the spectral range from 4800 Angstroms to 10600 Angstroms with a resolution of 55000. These spectra include some of the spectral lines most widely used as optical and near-infrared indicators of chromospheric activity such