EVOLUTION OF ROTATING LOW MASS STARS WITH ANGULAR-MOMENTUM LOSS

The evolutionary behavior of rotating low mass stars has been investigated with angular momentum loss by the magnetic stellar wind through the pre-main sequence and on the zero age main sequence phases. As the stars contract toward the zero age main sequence, angular momentum is removed from the convective envelope under the assumption that initially only the convective envelope is spun down in low mass stars. It is obtained that most of the angular momentum loss occurs prior to reaching the zero age main sequence. By the time of 7 10(8) yr, rotating low mass stars spin down to below 10 km s-1 surface rotational velocities. Hyades cluster data (Stauffer & Hartmann 1986) show almost the same trend with the isochrone of 7 10(8) yr, obtained in the present study.