5 papers · 1 filter
Radiation-Pressure Ejection of Planetary Nebulae in Asymptotic-Giant- Branch Stars
Allen V. Sweigart
We have investigated the possibility that radiation pressure might trigger planetary nebula (PN) ejection during helium-shell flashes in asymptotic- giant-branch (AGB) stars. We fi…
Gravonuclear Instabilities in Post-Horizontal-Branch Stars
Allen V. Sweigart, John C. Lattanzio, James P. Gray +1
We investigate the gravonuclear instabilities reported by Bono et al. (1997a,b) during the onset of helium-shell burning at the end of the horizontal-branch (HB) phase. These insta…
The Second-Parameter Effect in Metal-Rich Globular Clusters
Allen V. Sweigart
Recent Hubble Space Telescope (HST) observations by Rich et al. (1997) have shown that the metal-rich globular clusters (GCs) NGC 6388 and NGC 6441 exhibit a pronounced 2nd paramet…
Blue horizontal branch stars in metal-rich globular clusters. I. NGC 6388 and NGC 6441
S. Moehler, A. V. Sweigart, M. Catelan
We report the first results of an ongoing spectroscopic survey of blue horizontal branch stars in the metal-rich ([Fe/H] ~ -0.5) globular clusters NGC 6388 and NGC 6441. Based on d…
Hot stellar population synthesis from the UV spectrum: the globular cluster M79 (NGC 1904)
Jorick S. Vink, Sara R. Heap, Allen V. Sweigart +2
We have analyzed the far UV-spectrum of the globular cluster M79. We show that the nearly Gaussian mass distribution of zero-age horizontal-branch stars, as derived by Dixon et al.…