Title: Determining stellar parameters of asteroseismic targets: going beyond the use of scaling relations,
Abstract: Asteroseismic parameters allow us to measure the basic stellar properties of
field giants observed far across the Galaxy. Most of such determinations are,
up to now, based on simple scaling relations involving the large frequency
separation, \Delta\nu, and the frequency of maximum power, \nu$_{max}$. In this
work, we implement \Delta\nu\ and the period spacing, {\Delta}P, computed along
detailed grids of stellar evolutionary tracks, into stellar isochrones and
hence in a Bayesian method of parameter estimation. Tests with synthetic data
reveal that masses and ages can be determined with typical precision of 5 and
19 per cent, respectively, provided precise seismic parameters are available.
Adding independent information on the stellar luminosity, these values can
decrease down to 3 and 10 per cent respectively. The application of these
methods to NGC 6819 giants produces a mean age in agreement with those derived
from isochrone fitting, and no evidence of systematic differences between RGB
and RC stars. The age dispersion of NGC 6819 stars, however, is larger than
expected, with at least part of the spread ascribable to stars that underwent
mass-transfer events.