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 \sim 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 ( \sim -0.02 dex , on average ) and enhancement of refractories ( \sim 0.01 dex ) in WASP-94A relative to B ( standard errors are \sim 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 .