Results 11 to 20 of about 3,055 (216)
Symposium - International Astronomical Union, 1974 The properties of horizontal branch stars depend on the amount of carbon, nitrogen and oxygen that they contain but all theoretical models have difficulty in explaining those stars right at the blue end of the horizontal branch. The length of the theoretical evolutionary tracks always appears to be less than what is observed.
R. J. Tayler, J. E. Hesser
openaire +2 more sources
The horizontal-branch A stars [PDF]
Publications of the Astronomical Society of the Pacific, 1979 The observational determination of astrophysical parameters of horizontal-branch A stars is discussed. Effective temperatures, surface gravities, and bolometric magnitudes are determined for seven field horizontal-branch A stars, and their masses are calculated. The mean mass for these seven stars is 0.6 + or - 0.4 solar mass.
D. S. Hayes, A. G. D. Philip
openaire +1 more source
Planets around Extreme Horizontal Branch Stars [PDF]
AIP Conference Proceedings, 2011 We review three main results of our recent study: We show that a proper treatment of the tidal interaction prior to the onset of the common envelope (CE) leads to an enhance mass loss. This might increase the survivability of planets and brown dwarfs that enter a CE phase.
Ealeal Bear +4 more
openaire +4 more sources
The ages of stars: The horizontal branch [PDF]
Proceedings of the International Astronomical Union, 2008 AbstractHorizontal branch (HB) stars play a particularly important role in the “age debate,” since they are at the very center of the long-standing “second parameter” problem. In this review, I discuss some recent progress in our understanding of the nature and origin of HB stars.
openaire +2 more sources
Diffusion in the Atmospheres of Blue Horizontal-Branch Stars [PDF]
The Astrophysical Journal, 2000 We investigate the effects of diffusion in the atmospheres of hot horizontal-branch stars using a model atmosphere code including diffusion self-consistently. Equilibrium stratifications (i.e., for which the diffusion velocity equals zero in each layer) are computed for models of effective temperatures between 10,000 and 25,000 K. The stratified models
, Hui-Bon-Hoa, , LeBlanc, , Hauschildt
openaire +2 more sources
Rotation of Horizontal‐Branch Stars in Globular Clusters [PDF]
The Astrophysical Journal, 2000 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 ...
Sills, Alison, Pinsonneault, M. H.
openaire +3 more sources
Remarks concerning the masses of horizontal-branch A stars [PDF]
Symposium - International Astronomical Union, 1984 Studies are underway concerning the masses of horizontal-branch A stars. Hayes and Philip (1979) discussed masses determined for seven field HB stars using gravities and temperatures obtained from spectrophotometric scans. They found a mean mass of 0.6 M⊙ ± 0.4 for these stars. However, there was a strong trend of mass with temperature.
A. G. Davis Philip +2 more
openaire +1 more source
Horizontal branch evolution, metallicity, and sdB stars [PDF]
Astronomy & Astrophysics, 2011 Accepted for publication by A& ...
Michaud, Georges +2 more
openaire +4 more sources
Hot Horizontal‐Branch Stars in the Galactic Bulge. I. [PDF]
The Astrophysical Journal, 1999 We report the discovery of hot horizontal branch stars in the nuclear bulge of the Milky Way. Spectra from the 2dF instrument of the Anglo-Australian Telescope allow us to confirm their membership in the bulge through radial velocities. We also review the current observational information on hot horizontal branch stars in Milky Way clusters and the ...
Peterson, Ruth C. +3 more
openaire +2 more sources
Non-variable horizontal-branch stars [PDF]
Symposium - International Astronomical Union, 1997 For 25 years our ignorance of the physical basis of this mass loss process has been the barrier to progress in understanding horizontal branch morphology. I review some recent observational and theoretical results which may be giving us clues about the nature of the mass loss process.
openaire +1 more source