7 papers · 1 filter
On the Origin of Sulfur
Nils Ryde, David L. Lambert
We present our work on the halo evolution of sulfur, based on observations of the S I lines around 9220 A for ten stars for which the S abundance was obtained previously from much…
Evidence for Newly Synthesized Lithium in Interstellar Space
David C. Knauth, Steven R. Federman, David L. Lambert +1
As a part of a study on the variation in the 7Li/6Li ratio, high signal to noise, high resolution spectroscopy of Li I (6708 Angstroms) and K I (4044 Angstroms) were obtained towar…
Isotopic lithium abundances in five metal-poor disk stars
P. E. Nissen, D. L. Lambert, F. Primas +1
High resolution (R=110000), very high S/N spectra, centered on the 6707.8A LiI line have been obtained with the ESO Coude Echelle Spectrometer for five, metal-poor (-0.8 < [Fe/H] <…
The rise and fall of the NaMgAl stars
Jocelyn Tomkin, Bengt Edvardsson, David L. Lambert +1
We have made new abundance determinations for a sample of NaMgAl stars. These stars, which are a subgroup of the nearby metal-rich field F and G disk dwarfs, were first identified…
Lines of Circumstellar C2, CN, and CH+ in the Optical Spectra of Post-Agb Stars
Eric J. Bakker, David L. Lambert, Ewine F. van Dishoeck
Recent optical spectra of post-AGB stars show the presence of C2, CN, and CH+ originating in the circumstellar shell. We present here new, higher resolution spectra which provide c…
The Abundance of Boron in Evolved A- and B-Type Stars
Kim A. Venn, David L. Lambert, Michael Lemke
Boron abundances in A- and B-type stars may be a successful way to track evolutionary effects in these hot stars. The light elements -- Li, Be, and B -- are tracers of exposure to…