Discovery of Extended Blue Horizontal Branches in Two Metal-rich Globular Clusters
نویسندگان
چکیده
منابع مشابه
Blue horizontal branch stars in metal-rich globular clusters
Atmospheric parameters (Teff , log g), and radial velocities are derived for twelve candidate blue horizontal branch (HB) stars in the globular clusters 47 Tuc and NGC 362, which so far have been known to contain primarily red HB stars. The spectroscopic targets were selected from the catalog of hot stars detected in these clusters at 1600 Å using the Ultraviolet Imaging Telescope (UIT). Spectr...
متن کاملBlue horizontal branch stars in metal - rich globular clusters . I . NGC 6388 and NGC 6441 ⋆
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 data obtained with the ESO– New Technology Telescope (NTT), we provide gravities and temperatures for four stars in NGC 6388 and three stars in NGC 6441. These results are marginally inconsistent with the predictions o...
متن کاملBlue horizontal branch stars in metal - rich globular clusters . II . 47 Tuc and NGC 362
Atmospheric parameters (Teff , log g), and radial velocities are derived for twelve candidate blue horizontal branch (HB) stars in the globular clusters 47 Tuc and NGC 362, which so far have been known to contain primarily red HB stars. The spectroscopic targets were selected from the catalog of hot stars detected in these clusters at 1600 Å using the Ultraviolet Imaging Telescope (UIT). Spectr...
متن کاملThe Second-Parameter Effect in Metal-Rich Globular Clusters
Recent Hubble Space Telescope observations have found that the horizontal branches (HB’s) in the metal-rich globular clusters NGC 6388 and NGC 6441 slope upward with decreasing B−V . Such a slope is not predicted by canonical HB models and cannot be produced by either a greater cluster age or enhanced mass loss along the red-giant branch (RGB). The peculiar HB morphology in these clusters may p...
متن کاملBlue straggler production in globular clusters
Recent HST observations of a large sample of globular clusters reveal that every cluster contains between 40 and 400 blue stragglers. The population does not correlate with either stellar collision rate (as would be expected if all blue stragglers were formed via collisions) or total mass (as would be expected if all blue stragglers were formed via the unhindered evolution of a subset of the st...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 1997
ISSN: 0004-637X
DOI: 10.1086/310758