A test of Newton's law of gravity in the low acceleration regime using globular clusters is presented and new results for the core collapsed globular cluster NGC 7099 given. The run of the gravitational potential as a function of distance is probed by studying the velocity dispersion profile of the cluster, as derived from a set of 125 radial

We describe a new method involving wavelet transforms for deriving the wind velocity associated with atmospheric turbulent layers from Generalized SCIDAR measurements. The algorithm analyses the cross-correlation of a series of scintillation patterns separated by lapses of Δt, 2Δt, 3Δt, 4Δt and 5Δt using wavelet transforms. Wavelet analysis

Aims.We present a search for low-mass brown dwarfs in the Pleiades open cluster. The identification of Pleiades members fainter and cooler than those currently known allows us to constrain evolutionary models for L dwarfs and to extend the study of the cluster mass function to lower masses. Methods: .We conducted a 1.8 deg2 near-infrared J-band

This paper presents a homogeneous study of abundances in a sample of 79 northern Galactic planetary nebulae (PNe) whose morphological classes have been uniformly determined. Ionic abundances and plasma diagnostics were derived from selected optical line strengths in the literature, and elemental abundances were estimated with the ionization

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We argue on the basis of astrometric and spectroscopic data that the ultramassive white dwarf GD50 is associated with the star formation event that created the Pleiades and is possibly a former member of this cluster. Its cooling age (~60 Myr) is consistent with it having evolved essentially as a single star from a progenitor with a mass M >