We present astrometric monitoring data of the binary brown dwarf DENIS-P J1228.2-1547. The data have been obtained with the Hubble Space Telescope over a time span of 5.5 yr, and confirm that DENIS-P J1228.2-1547 is indeed a common proper motion, i.e., physical, binary. The data cover about 1/8th of the binary orbit, indicating an orbital period of

In this paper we present beryllium (Be) abundances in a large sample of 41 extra-solar planet host stars, and for 29 stars without any known planetary-mass companion, spanning a large range of effective temperatures. The Be abundances were derived through spectral synthesis done in standard Local Thermodynamic Equilibrium, using spectra obtained

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We report atmospheric parameter estimates (Teff, log g, [Fe/H]) and other information (radial velocities, proper motions, distance estimates) for roughly 40,000 stars (out of a total of some 75,000) from the third public release of the Sloan Digital Sky Survey (SDSS), DR-3. As part of this exercise, we have compiled a set of spectral templates that

We define a method for the analysis of the integrated spectra of extragalactic globular clusters that provides more reliable measures of the age, metallicity and α-element abundance ratio than have so far been achieved. The method involves the simultaneous fitting of up to 25 Lick indices in a χ2 fitting technique that maximizes the use of the

The observational picture of the enigmatic O-type spectrum variable HD 191612 has been sharpened substantially. A symmetrical, low-amplitude light curve with a period near 540 days has recently been reported from Hipparcos photometry. This period satisfies all of the spectroscopy since at least 1982, including extensive new observations during 2003