The Rotation of Red Giants and Horizontal Branch Stars
نویسندگان
چکیده
منابع مشابه
Rotation Velocities of Red and Blue Field Horizontal-Branch Stars
We present measurements of the projected stellar rotation velocities (v sin i) of a sample of 45 candidate field horizontal-branch (HB) stars spanning a wide range of effective temperature, from red HB stars with Teff ' 5000 K to blue HB stars with Teff of 17000 K. Among the cooler blue HB stars (Teff = 7500– 11500 K), we confirm prior studies showing that although a majority of stars rotate at...
متن کاملWhy Hot Horizontal Branch Stars Can Appear Redder Than Red Giants ⋆
In this paper we report on a curious feature in the V , (U − B) color-magnitude diagrams of globular clusters. In our database, we find that a considerable fraction of blue horizontal branch stars, hotter than the instability strip and cooler than the Grundahl et al. (1999) jump (i.e., 6000 ≤ Teff(K)≤ 10000), have (U − B) colors redder than their red giant progenitors. This red incursion is not...
متن کاملRotation and abundance anomalies in blue horizontal-branch stars
To address the puzzling photometric properties of horizontal branch stars in Galactic GCs, several different groups have undertaken detailed spectroscopic analyses of individual blue HB stars. Hotter BHB stars show strong metal enhancement and helium depletion, likely due to atomic diffusion, and slow rotation velocities, in contrast to the cooler BHB stars, which have a bimodal distribution of...
متن کاملRotation 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...
متن کاملRotation of Horizontal Branch Stars in Globular Clusters
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...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 2004
ISSN: 0074-1809
DOI: 10.1017/s0074180900195440