Abundance anomalies in hot horizontal branch stars of the galactic globular cluster NGC1904

Fabbian, D.; Recio-Blanco, A.; Gratton, R. G.; Piotto, G.
Referencia bibliográfica

Astronomy and Astrophysics, Volume 434, Issue 1, 2005, pp.235-245

Fecha de publicación:
4
2005
Número de autores
4
Número de autores del IAC
0
Número de citas
42
Número de citas referidas
37
Descripción
We present abundance measurements, based on high-resolution optical spectroscopic data obtained with the Ultraviolet and Visual Echelle Spectrograph mounted on Kueyen (Very Large Telescope UT2), for ten stars in the extended blue horizontal branch of the Galactic globular cluster NGC 1904 (M79). In agreement with previous findings for other clusters, we obtain normal abundances for stars cooler than T_eff˜ 11 000 K, and largely anomalous abundances for hotter stars: large He depletions, and overabundances of Fe, Ti, Cr, P and Mn. The abundances of Mg, Si and Ca are roughly normal, in the hot stars as well as in the cooler ones. This abundance pattern can be attributed to the onset of diffusion and to radiation pressure in the stable atmospheres of hot horizontal branch stars.