Meridional circulation versus diffusion in stellar envelopes

Journal Article · Thu Jul 01 04:00:00 EDT 1982 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/160083· OSTI ID:5081046

Michaud, G

Tassoul and Tassoul have recently obtained self-consistent solutions for meridional circulation throughout chemically homogeneous stars. The meridional circulation velocities they determined are here compared to diffusion velocities of helium below the He II convection zone. It is shown that the He II convection zone can disappear only in stars with equatorial rotational velocities smaller than 90 km s/sup -1/. This is in agreement with the cutoff velocity observed for the MgMn stars. This maximum velocity for the disappearance of the He II convection zone depends sensitively on gravity so that there is not one equatorial rotational velocity below which all stars should become HgMn. It depends on the evolutionary status and on how the star was slowed down. On the other hand, the rotational motion is turbulent, and the effect this turbulence has on chemical separation is poorly known.

• Research Organization: Departement de Physique, Universite de Montreal
• OSTI ID: 5081046
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 258:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CHARGED PARTICLES
CONVECTION
DIFFUSION
HELIUM IONS
IONS
MATHEMATICAL MODELS
MOTION
ROTATION
STAR MODELS
STARS
STELLAR ATMOSPHERES
VARIABLE STARS