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The Cosmic Production of Helium
This work estimates the cosmic production rate of helium relative to metals using K dwarf stars in the Hipparcos catalog with accurate spectroscopic metallicities using ΔY/ΔZ = 2.1 ± 0.4 at the 68% confidence level.
Stars on the main sequence are expected to be completely convective if their mass lies below a certain value, Mcc. Standard stellar structure codes suggest that Mcc is in the range 0.3-0.4 M☉. In the
The effects of diffusion due to gravity and due to composition gradients on the rate of hydrogen burning in a cooling degenerate dwarf. I - The case of a thick helium buffer layer
The evolution of an isolated carbon-oxygen degenerate dwarf which has a surface layer initially containing hydrogen and helium and is of mass 0.6 M/sub sun/ is followed from the planetary nebula
Ages of globular clusters: a new approach
A B ST R A C T W has applied a new m ethod to analyzethehorizontal branch (HB)m orphology in relation to distribution of starsnearthered giant branch (RGB) tipfortheglobular clusters to greater accuracy than conventionalisochrone �tting.
The mass of helium in white dwarf stars and the formation and evolution of hydrogen-deficient post-AGB stars
We use two sets of ‘cradle-to-grave’ evolutionary calculations to investigate how the mass of the helium buffer layer between the CO core and the hydrogen-burning shell in thermally pulsing
Sakurai’s Object, V605 Aquilae, and FG Sagittae: An Evolutionary Sequence Revealed
We have completed a grid of stellar evolution calculations to study the behavior of the born-again phenom- enon. All our evolutionary sequences begin with a uniform composition 1 Mstar on the
How much hydrogen is there in a white dwarf
Stratified hydrogen/helium envelope models in diffusive equilibrium are calculated for a 0.6-solar-mass white dwarf for effective temperatures between 10,000 and 80,000 K in order to investigate the
Precision modelling of M dwarf stars: the magnetic components of CM Draconis
The eclipsing binary CM Draconis (CM Dra) contains two nearly identical red dwarfs of spectral class dM4.5. The masses and radii of the two components have been reported with unprecedentedly small