Constraining churning and blurring in the Milky Way using large
  spectroscopic surveys -- an exploratory study
  We have investigated the possibilities to quantify how much stars move in the
Milky Way stellar disk due to diffuse processes (i.e. so called blurring) and
due to influences from spiral arms and the bar (i.e. so called churning). To
this end we assume that it is possible to infer the formation radius of a star
if we know their elemental abundances and age as well as the metallicity
profile of the interstellar medium at the time of the formation of the star.
Using this information, coupled with orbital information derived from Gaia DR2
data and radial velocities from large spectroscopic surveys, we show that it is
possible to isolate stellar samples such that we can start to quantify how
important the role of churning is. We use data from APOGEE DR14, parallaxes
from Gaia and stellar ages based on C and N elemental abundances in the stars.
In our sample, we find that about half of the stars have experienced some sort
of radial migration (based solely on their orbital properties), 10 % have
likely have suffered only from churning, whilst a modest 5-7 % of stars have
never experienced either churning or blurring making them ideal tracers of the
original properties of the cool stellar disk. Our investigation shows that it
is possible to put up a framework where we can begin to quantify churning and
blurring an important. Important aspects for future work would include to
investigate how selection effects should be accounted for.
