We have calculated the structural models of sdB stars and their corresponding theoretical frequencies needed to carry out an asteroseismological analysis.

We obtained moderate/low resolution spectroscopy (2/5 AA FWHM) of the microquasar candidate MCQC J162847-4152 (hereafter J1628) on 2003 May 5/6/13 (UT) and June 22/23/25 with the B&C spectrograph mounted on the 6.5-m Baade and Clay telescopes at LCO. In addition, high resolution spectra (R~27000 and 36000 in the blue and red respectively) were

We report the results of a high-resolution spectroscopic survey of all the stars more luminous than M_V = 6.5 mag within 14.5 pc from the Sun. The Hipparcos catalog's completeness limits guarantee that our survey is comprehensive and free from some of the selection effects in other samples of nearby stars. The resulting spectroscopic database

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We confirm the planetary nebula nature of two sources: PN G000.2+06.1 and PN G002.3+02.2, previously identified by Terzan in a photometric survey toward the Galactic center as objects possibly belonging to this class. Optical images taken in Hα reveal the extended morphology of the nebulae, while spectroscopic observations allow us to determine

We report the results of a non-LTE Fe, O and Mg abundance analysis of the carbon-nitrogen-rich ultra-metal-poor giants CS 29498-043 and CS 22949-037. The abundance of oxygen has been derived from measurements of the oxygen triplet at 7771-5 Å in high resolution spectra obtained with KeckI/HIRES and the forbidden line [O I] 6300 Å detected in the