Mass and age of red giant branch stars

In this paper, we estimate masses and ages of 6940 red giant branch (RGB) stars with asteroseismic parameters deduced from Kepler photometry and stellar atmospheric parameters derived from LAMOST spectra. The typical uncertainties of mass is a few per cent, and that of age is ~20 per cent.

The sample stars reveal two separate sequences in the age-[{alpha}/Fe] relation - a high-{alpha} sequence with stars older than ~8Gyr and a low-{alpha} sequence composed of stars with ages ranging from younger than 1Gyr to older than 11Gyr. We further investigate the feasibility of deducing ages and masses directly from LAMOST spectra with a machine learning method based on kernel based principal component analysis, taking a sub-sample of these RGB stars as a training data set.