On the possibility that rotation causes
latitudinal abundance variations in stars
John M. Porter
Astrophysics Research Institute,
Liverpool John Moores University,
Twelve Quays House, Egerton Wharf, Birkenhead. L41 1LD UK
The effect of rotation of a star on the distribution of chemical
species in radiative zones is discussed. Gravity darkening generates a
large radiative force on heavy element ions which is directed toward
the equatorial plane. Taking iron as an example, it is shown that
this force may produce drift velocities similar to, and larger than,
the typical velocities of bulk motion due to meridional circulation.
This potentially allows large chemical abundance inhomogeneities to
build up across a meridian over the lifetime of the star --
particularly near the equatorial plane. This enhancement may be
significantly reduced if the mass loss of the star is strongly
metallicity dependent, in which case the mass-loss rate may be
enhanced in the equatorial plane.
1999, A&A, 341, 560
|