Rotation among Orion IC G stars - Angular momentum loss considerations in pre-main-sequence stars

A major impetus regarding the present investigation has been the recent trend toward the assignment of low rotational velocities to T Tauri stars. Vogel and Kuhi (1981) found that three-fourths of a sample of late-type pre-main-sequence (PMS) stars in NGC 2264 and Taurus-Auriga rotate below their observational limit of 25-35 km /s. The present investigation is concerned with a large sample of G stars in the post-T Tauri Orion Ic associations at a higher spectroscopic resolution than was available to Vogel and Kuhi. The selected sample appears to span ranges in mass and age of about two and four, respectively. Spectra of the PMS stars in this survey appear to be quite suitable for rotational analysis. Fourier analysis of the lines studied results in a rotational velocity distribution which is highly non-Maxwellian.