High resolution Keck HIRES and Gemini GRACES spectra are combined with Gaia DR2 photometry and astrometry to re-examine the low-metallicity , kinematically interesting dwarf stars studied by Stephens & Boesgaard ( 2002 ) .
These stars , spanning a metallicity range of -1.5 > [ Fe/H ] > -3 , were originally selected as outer halo dwarf stars because of their large apocentric radii , large distances from the Milky Way plane and/or highly elliptical or retrograde orbits .
Using additional chemical and kinematic criteria , we select a subsample of six stars ( test cases ) to redetermine stellar parameters and abundances using new model atmospheres and updated atomic data .
We confirm two of the six stars in our sample to be very metal-poor , with [ Fe/H ] \sim - 2.3 ( G158-100 , G037-037 ) and find two other stars to be Mg-poor at intermediate metallicities [ Fe/H ] \sim - 1.5 ( G184-007 and G189-050 ) .
The latter signature is suggestive of origins in an accreted dwarf galaxy .
Gaia DR2 data is used to redetermine the orbital parameters for the entire SB02 sample .
We find nine stars to be dynamically coincident with the Gaia -Enceledas satellite merger , including one very low metallicity star ( G238-030 ) ( [ Fe/H ] \sim - 3.6 ) .
Another 17 stars are found to be dynamically coincident with the Gaia -Sequoia accretion event , including one very metal-poor star near [ Fe/H ] = -3.5 .
Both metal-poor stars have low masses and isochrone ages older than 10 Gyr .
A knee in [ \alpha /Fe ] is found in the Gaia -Enceladus associated stars , near [ Fe/H ] \sim - 1.6 , while the location of an [ \alpha /Fe ] is less clear in the Gaia -Sequoia sample .
If the metal-poor stars in these samples are true members of the Gaia -Enceledas and Gaia -Sequoia remnants , they present unique opportunities to probe the low metallicity tail and early star formation history of these systems .