  Binary stars provide an ideal laboratory for investigating the potential
effects of planet formation on stellar composition. Assuming the stars formed
in the same environment/from the same material, any compositional anomalies
between binary components might indicate differences in how material was
sequestered in planets, or accreted by the star in the process of planet
formation. We present here a study of the elemental abundance differences
between WASP-94AB, a pair of stars that each host a hot Jupiter exoplanet. The
two stars are very similar in spectral type (F8 and F9), and their ~2700 AU
separation suggests their protoplanetary disks were likely not influenced by
stellar interactions, but WASP-94Ab's orbit -- misaligned with the host star
spin axis and likely retrograde -- points towards a dynamically active
formation mechanism, perhaps different than that of WASP-94Bb, which is not
misaligned and has nearly circular orbit. Based on our high-quality spectra and
strictly relative abundance analysis, we detect a depletion of volatiles
(~-0.02 dex, on average) and enhancement of refractories (~0.01 dex) in
WASP-94A relative to B (standard errors are ~0.005 dex). This is different than
every other published case of binary host star abundances, in which either no
significant abundance differences are reported, or there is some degree of
enhancement in all elements, including volatiles. Several scenarios that may
explain the abundance trend are discussed, but none can be definitively
accepted or rejected. Additional high-contrast imaging observations to search
for companions that may be dynamically affecting the system, as well as a
larger sample of binary host star studies, are needed to better understand the
curious abundance trends we observe in WASP-94AB.
