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UV Spectral Dating of Stars and Galaxies
S. R. Heap, T. M. Brown, I. Hubeny +17
An echelle spectrogram (R = 30,000) of the 2300-3100 A region in the ultraviolet spectrum of the F8V star 9 Comae is presented. The observation is used to calibrate features in the…
On the Production of Bright RR Lyrae Variables in Metal-Rich Globular Clusters
A. V. Sweigart, M. Catelan
Recent HST observations of the metal-rich bulge clusters NGC 6388 and NGC 6441 by Rich et al. (1997) have found that the horizontal branches (HBs) in these clusters slope upward wi…
Helium Mixing in Globular Cluster Stars
A. V. Sweigart
The observed abundance variations in globular cluster red giants indicate that these stars may be mixing helium from the hydrogen shell outward into the envelope, presumably as a r…
Proton-Capture Nucleosynthesis in Globular Cluster Red Giant Stars
Robert M. Cavallo, Allen V. Sweigart, Roger A. Bell
We follow the static abundance profiles of the C, N, O, Ne, Na, Mg, and Al isotopes around the hydrogen-burning shell (H shell) of globular cluster red-giant-branch (RGB) stellar m…
Bimodality and Gaps on Globular Cluster Horizontal Branches. II. The Cases of NGC 6229, NGC 1851 and NGC 2808
M. Catelan, J. Borissova, A. V. Sweigart +1
The outer-halo globular cluster NGC 6229 has a peculiar horizontal-branch (HB) morphology, with clear indications of a bimodal HB and a ``gap" on the blue HB. In this paper, we pre…