On the Number Ratio of Horizontal Branch Stars to Red Giant Stars in Globular Clusters
نویسندگان
چکیده
منابع مشابه
Rotation of Hot Horizontal Branch Stars in Galactic Globular Clusters
We present high resolution UVES+VLT spectroscopic observations of 61 stars in the extended blue horizontal branches of the Galactic globular clusters NGC 1904 (M79), NGC 2808, NGC 6093 (M80), and NGC 7078 M15). Our data reveal for the first time the presence in NGC 1904 of a sizable population of fast (vsini ≥ 20 km/s) horizontal branch (HB) rotators, confined to the cool end of the EHB, simila...
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The rotation of horizontal branch stars places important constraints on angular momentum evolution in evolved stars and therefore rotational mixing on the giant branch. Prompted by new observations of rotation rates of horizontal branch stars, we calculate simple models for the angular momentum evolution of a globular cluster giant star from the base of the giant branch to the star’s appearance...
متن کاملBlue 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 کاملHorizontal Branch A- and B-type Stars in Globular Clusters
Globular clusters offer ideal laboratories to test the predictions of stellar evolution. When doing so with spectroscopic analyses during the 1990s, however, the parameters we derived for hot horizontal branch stars deviated systematically from theoretical predictions. The parameters of cooler, A-type horizontal branch stars, on the other hand, were consistent with evolutionary theories. In 199...
متن کاملThe Chemical Composition of Red Giant Branch Stars in the Galactic Globular Clusters Ngc
We present radial velocities and chemical abundances for red giant branch stars in the Galactic bulge globular clusters NGC 6342 and NGC 6366. The velocities and abundances are based on measurements of high resolution (R & 20,000) spectra obtained with the MMT–Hectochelle and WIYN–Hydra spectrographs. We find that NGC 6342 has a heliocentric radial velocity of +112.5 km s (σ = 8.6 km s), NGC 63...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1981
ISSN: 0074-1809
DOI: 10.1017/s0074180900074088