The fragile and rare isotope 6Li has a spallative origin. It is rapidly destroyed in solar-type stars while fully preserved in low-mass brown dwarfs and planets. So far, 6Li has been unambigiously detected in only few metal-poor halo and disk stars whereas it has never been observed with a high level of confidence in any metal-rich or even solar

We report the largest mass-loss rate of ~5 % of the solar mass per year, directly observed in any stellar object so far during the recent outburst of the Yellow Hypergiant ρ Cas. In the fall of 2000, the enigmatic cool luminous supergiant dimmed by more than a full visual magnitude, thereby changing its spectral type form early F- to early M-type

We have determined the gravitational torque of a sample of 45 galaxies observed at K band with the 4.2m William Herschel Telescope. The results of this sample, combined with those for a sample of 30 galaxies previously analysed (Buta & Block 2001), show that the gravitational bar torque correlates only weakly with the optical bar type listed in the

We present a study of the grand-design spiral galaxy NGC 5248 (Jogee et al. 2002a,b) based on a combination of multi-wavelength % optical, near-infrared, and CO (J=1--O) observations and hydrodynamical modeling.

We derived photospheric parameters, mass-loss rates, and wind velocities of Galactic O6-O7 stars by analyzing high-resolution spectra in the far-UV and UV ranges with line-blanketed, hydrodynamic, non-LTE spherical models. We combined spectra from the Far Ultraviolet Spectroscopic Explorer (FUSE) in the range 905-1187 Å and International

We have studied the effect of the mass of the central star (CS) on the gas evolution during the planetary nebula (PN) phase. We have performed numerical simulations of PN formation using CS tracks for six stellar core masses corresponding to initial masses from 1 to 5 Msolar. The gas structure resulting from the previous asymptotic giant branch