2000ApJ...533..984S -
Astrophys. J., 533, 984-997 (2000/April-3)
On the formation of helium double degenerate stars and pre-cataclysmic variables.
SANDQUIST E.L., TAAM R.E. and BURKERT A.
Abstract (from CDS):
The evolution of low-mass (M<2.5 M☉) binaries through the common envelope phase has been studied for systems in which one member is on its first ascent of the red giant branch. Three-dimensional hydrodynamical simulations have been carried out for a range of red giant masses (1-2 M☉) with degenerate helium cores (0.28-0.45 M☉) and companions (0.1-0.45 M☉) for initial orbital periods ranging from ∼15 to 1000 days. The results suggest that these low-mass binary systems can survive the common envelope phase provided that the helium degenerate core is more massive than about 0.2-0.25 M☉ and that the mass of the red giant progenitor is ≲2 M☉. Specific applications are made to observed double helium degenerate systems, pre-cataclysmic variables, and subdwarf B stars in order to place constraints on progenitor systems evolving through the common envelope phase. For the observed short-period double degenerate systems, it is found that evolutionary scenarios involving two phases of common envelope evolution are not likely and that a scenario involving an Algol-like phase of mass transfer followed by a common envelope phase is viable, suggesting that the first-formed white dwarf is often reheated by nuclear burning on its surface. A formation mechanism for two subdwarf B stars observed in eclipsing short-period binaries with low-mass main-sequence stars is also described.
Abstract Copyright:
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Journal keyword(s):
Stars: Binaries: Close - Stars: Circumstellar Matter - Hydrodynamics - Stars: Novae, Cataclysmic Variables - Stars: Evolution - Stars: Interiors
Simbad objects:
11
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