Cool Stars 14 - Submitted Abstract # 289
This version created on 05 October 2006

Models fo Differentially Rotating, 1 -2 Solar Mass Main-Sequence Stars


Keith MacGregor, HAO/NCAR
Stephen Jackson, HAO/NCAR
Andrew Skumanich, HAO/NCAR
Travis Metcalfe, HAO/NCAR

We present models for chemically homogeneous, differentially rotating,
main-sequence stars with masses in the range from 1 to 2 solar masses.
The models were constructed using a code based on a reformulation of
of the self-consistent field method of computing the equilibrium
stellar structure for a specified conservative internal rotation law.
Relative to nonrotating stars of the same mass, these models all have
reduced luminosities and effective temperatures, and flattened
photospheric shapes (i.e., decreased polar radii) with equatorial
radii that can be larger or smaller, depending on the degree of
differential rotation.  For a fixed ratio of the axial rotation rate
to the surface equatorial rotation rate, increasingly rapid rotation
generally deepens convective envelopes, shrinks convective cores, and
can lead to the presence of a convective core (envelope) in a 1 (2)
solar mass model, a feature that is absent in a nonrotating star of
the same mass.  The positions of differentially rotating models for a
given mass in the H-R diagram can be shifted in such a way as to
approximate the nonrotating ZAMS for lower mass stars.  Implications
of these results include (i) possible ambiguities arising from
similarities between the properties of rotating and nonrotating models
of different masses, (ii) a reduced radiative luminosity for a young,
rapidly rotating Sun, (iii) modified rates of lithium destruction by
nuclear processes in the layers beneath an outer convective envelope,
and (iv) the excitation of solar-like oscillations and the operation
of a solar-like hydromagnetic dynamo in some 1.5 - 2 solar mass stars.

----------------------------------