TY - JOUR
T1 - Abundance anomalies in hot horizontal branch stars of the galactic globular cluster NGC 1904
AU - Fabbian, D.
AU - Recio-Blanco, A.
AU - Gratton, R. G.
AU - Piotto, G.
PY - 2005/4
Y1 - 2005/4
N2 - 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 Teff ∼11000 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.
AB - 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 Teff ∼11000 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.
KW - Branch stars: abundances
KW - Globular clusters: general
KW - Globular clusters: individual: M79
KW - Stars: horizontal
UR - http://www.scopus.com/inward/record.url?scp=17444393921&partnerID=8YFLogxK
U2 - 10.1051/0004-6361:20035862
DO - 10.1051/0004-6361:20035862
M3 - Article
SN - 0004-6361
VL - 434
SP - 235
EP - 245
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
IS - 1
ER -