Forty years ago Burbidge, Burbidge, Fowler, and Hoyle combined what we would now call fragmentary evidence from nuclear physics, stellar evolution and the abundances of elements and isotopes in the solar system as well as a few stars into a synthesis of remarkable ingenuity. Their review provided a foundation for forty years of research in all of the aspects of low energy nuclear experiments and theory, stellar modeling over a wide range of mass and composition, and abundance studies of many hundreds of stars, many of which have shown distinct evidence of the processes suggested by B 2 FH. In this review we summarize progress in each of these fields with emphasis on the most recent developments. [S0034-6861(97)

We present a detailed chemical composition analysis of 35 red giant stars in the globular cluster M 22. High resolution spectra for this study were obtained at five observatories, and analyzed in a uniform manner. We have determined abundances of representative light proton-capture, α, Fe-peak and neutron-capture element groups. Our aim is to better understand the peculiar chemical enrichment history of this cluster, in which two stellar groups are characterized by a different content in iron, neutron capture elements Y, Zr and Ba, and α element Ca

From chemical abundance analysis of stars in the Sagittarius dwarf spheroidal galaxy (Sgr), we conclude that the α-element deficiencies cannot be due to the Type Ia supernova (SN Ia) time-delay scenario of Tinsley. Instead, the evidence points to low [α/Fe]

We used high-resolution, high signal-to-noise ratio spectra obtained with the Very Large Telescope and the UVVisual Echelle Spectrograph to determine abundances of 17 elements in four red giants in the Sculptor (Scl ) dwarf spheroidal galaxy. Our ½Fe=H -values range from À2.10 to À0.97, confirming previous findings of a large metallicity spread. We combined our data with similar data for five Scl giants studied recently by Shetrone et al. to form one of the largest samples of high-resolution abundances yet obtained for a dwarf spheroidal galaxy, covering essentially the full known metallicity range in this galaxy. These properties allow us to establish trends of ½X=Fe with ½Fe=H for many elements X. The trends are significantly different from the trends seen in Galactic halo and globular cluster stars. This conclusion is evident for most of the elements from oxygen to manganese. We compare our Scl sample with the most similar Galactic counterparts and find substantial differences remain even with these stars. The many discrepancies in the relationships between ½X=Fe as seen in Scl compared with Galactic field stars indicate that our halo cannot be made up in bulk of stars similar to those presently seen in dwarf spheroidal galaxies like Scl, corroborating similar conclusions reached by Shetrone et al., Fulbright, and Tolstoy et al. These results have serious implications for the Searle-Zinn and hierarchical galaxy formation scenarios. We also find that the most metal-rich star in our sample is a heavy element-rich star. This star and the ½Ba=Eu trend we see indicate that asymptotic giant branch stars must have played an important role in the evolution of the s-process elements in Scl. A very high percentage of such heavy-element stars are now known in dwarf spheroidals compared with the halo, further mitigating against the formation of the halo from such objects.

▪ Abstract  Absolute magnitudes are estimated for carbon stars of various subtypes in the Hipparcos catalogue and as found in the Magellanic Clouds. Stellar radii fall within the limits of 2.4–4.7 AU. The chemical composition of carbon stars indicates that the C-N stars show nearly solar C/H, N/H, and 12C/13C ratios. This indicates that much of the C and N in our Galaxy came from mass-losing carbon stars. Special carbon stars such as the C-R, C-H, and dC stars are described. Mass loss from asymptotic giant branch carbon stars, at rates up to several × 10−5 M[Formula: see text] year−1, contributes about half of the total mass return to the interstellar medium. R stars do not lose mass and may be carbon-rich red giants. The mass loss rates for Miras are about 10 times higher than for SRb and Lb stars, whose properties are similar enough to show that they are likely to belong to the same population. The distribution of carbon star mass loss rates peaks at about 10−7 M[Formula: see text] year−1, close to the rate of growth of the core mass and demonstrative of the close relationship between mass loss and evolution. Infrared spectroscopy shows that dust mixtures can occur. Detached shells are seen around some stars; they appear to form on the time scales of the helium shell flashes and to be a normal occurrence in carbon star evolution.