Rotational studies of late-type stars. II. Ages of solar-type stars and the rotational history of the Sun.

Main-sequence stars later than approximately F5 have little angular momentum. Kraft (1967) has studied the loss of angular momentum in stars, taking into account late-F dwarfs with masses corresponding to 1.2 solar masses. The present investigation has the objective to consider the problem of angular momentum loss for stars as near one solar mass as possible, and to compare the sun to similar stars. This objective made it necessary to measure the small 'v sin i' values typical of these stars. The required techniques were discussed in the first part of the investigation. In the current part of the investigation, the v sin i values of solar-type stars are analyzed and compared to the Li ages. It is assumed that all stars start with the same Li abundance, and that the Li depletion rate depends only on the stellar mass. The assumption is made that the sun is typical for its mass and age. These assumptions can be tested observationally, but much work remains to be done.