Using APOGEE Wide Binaries to Test Chemical Tagging with Dwarf Stars
  Stars of a common origin are thought to have similar, if not nearly
identical, chemistry. Chemical tagging seeks to exploit this fact to identify
Milky Way subpopulations through their unique chemical fingerprints. In this
work, we compare the chemical abundances of dwarf stars in wide binaries to
test the abundance consistency of stars of a common origin. Our sample of 31
wide binaries is identified from a catalog produced by cross-matching APOGEE
stars with UCAC5 astrometry, and we confirm the fidelity of this sample with
precision parallaxes from Gaia DR2. For as many as 14 separate elements, we
compare the abundances between components of our wide binaries, finding they
have very similar chemistry (typically within 0.1 dex). This level of
consistency is more similar than can be expected from stars with different
origins (which show typical abundance differences of 0.3-0.4 dex within our
sample). For the best measured elements, Fe, Si, K, Ca, Mn, and Ni, these
differences are reduced to 0.05-0.08 dex when selecting pairs of dwarf stars
with similar temperatures. Our results suggest that APOGEE dwarf stars may
currently be used for chemical tagging at the level of $\sim$0.1 dex or at the
level of $\sim$0.05 dex when restricting for the best-measured elements in
stars of similar temperatures. Larger wide binary catalogs may provide
calibration sets, in complement to open cluster samples, for on-going
spectroscopic surveys.
