The Spin of a Star Reveals Its Age 67
eldavojohn writes "Some soon-to-be-published research on gyrochronology has yielded a possible method for more accurately determining a star's age. While determining the age of stars in clusters has been done using the patterns of its color and brightness, singular stars are much more difficult. By comparing established age information from clusters and analyzing the spin of stars, the researchers have established a defined relationship between color (mass), spin and age giving them the beginning of a guide of 'stellar clocks.' This was accomplished after four painstaking years of collecting data from 71 single dwarf members of the open cluster NGC6811 and establishing a model using data from Kepler."
Re:Where is the angular momentum going? (Score:4, Informative)
OK, I've done some cursory research (abstracts and intros of a few papers.) I didn't find a review, however it seems that there has been quite a bit written about such angular momentum transfers, and the age-rotational period-mass relationship for stars. (So this result is a step in an already developed field, not a breakthrough.)
There was mention of interactions with a magnetized solar wind (i.e. a combination of my points 3 and 4 above) and also something called the Tayler-Spruit dynamo, which I think is about angular momentum transport between the star's core and envelope. For a young star, you'd expect the core to rotate faster than the envelope (conservation of angular momentum during the contraction) but the sun rotates like a solid body - same rotation period for all depths (or as far as we can probe by helioseismology.) The Tayler-Spruit appears to be a possible explanation for how a middle aged star like the sun can rotate like a solid body.