  The Halo Assembly in Lambda Cold Dark Matter: Observations in 7 Dimensions
(HALO7D) survey measures the kinematics and chemical properties of stars in the
Milky Way (MW) stellar halo to learn about the formation of our Galaxy. HALO7D
consists of Keck II/DEIMOS spectroscopy and Hubble Space Telescope-measured
proper motions of MW halo main sequence turn-off (MSTO) stars in the four
CANDELS fields. HALO7D consists of deep pencil beams, making it complementary
to other contemporary wide-field surveys. We present the [Fe/H] and
[$\alpha$/Fe] abundances for 113 HALO7D stars in the Galactocentric radial
range of $\sim 10-40$ kpc. Using the full 7D chemodynamical data (3D positions,
3D velocities, and abundances) of HALO7D, we measure the velocity anisotropy,
$\beta$, of the halo velocity ellipsoid for each field and for different
metallicity-binned subsamples. We find that two of the four fields have stars
on very radial orbits, while the remaining two have stars on more isotropic
orbits. Separating the stars into high, mid, and low [Fe/H] bins at $-2.2$ dex
and $-1.1$ dex for each field separately, we find differences in the
anisotropies between the fields and between the bins; some fields appear
dominated by radial orbits in all bins while other fields show variation
between the [Fe/H] bins. These chemodynamical differences are evidence that the
HALO7D fields have different fractional contributions from the progenitors that
built up the MW stellar halo. Our results highlight the additional information
that is available on smaller spatial scales when compared to results from a
spherical average of the stellar halo.
