Climbing the cosmic ladder with stellar twins in RAVE with Gaia
  We apply the twin method to determine parallaxes to 232,545 stars of the RAVE
survey using the parallaxes of Gaia DR1 as a reference. To search for twins in
this large dataset, we apply the t-stochastic neighbour embedding t-SNE
projection which distributes the data according to their spectral morphology on
a two dimensional map. From this map we choose the twin candidates for which we
calculate a chi^2 to select the best sets of twins. Our results show a
competitive performance when compared to other model-dependent methods relying
on stellar parameters and isochrones. The power of the method is shown by
finding that the accuracy of our results is not significantly affected if the
stars are normal or peculiar since the method is model free. We find twins for
60% of the RAVE sample which is not contained in TGAS or that have TGAS
uncertainties which are larger than 20%. We could determine parallaxes with
typical errors of 28%. We provide a complementary dataset for the RAVE stars
not covered by TGAS, or that have TGAS uncertainties which are larger than 20%,
with model-free parallaxes scaled to the Gaia measurements.
