Constraining the shape of Milky Way satellites with distance gradients
  We combine the Dark Energy Camera Legacy Survey (DECaLS) DR8 photometry with
Gaia photometry to study the 3-D structure of Bootes I, Draco, Ursa Minor,
Sextans and Sculptor dwarf galaxies using blue horizontal branch (BHB) stars as
distance indicators. We construct a new colour-absolute magnitude of BHB stars
that we use to measure the distance gradients within the body of the dwarf
galaxies. We detect a statistically significant non-zero gradient only in
Sextans and Sculptor. Through modeling of the gradient and 2-D density of the
systems by triaxial Plummer models we find that the distance gradients in both
dwarf galaxies are inconsistent with prolate shape, but compatible with oblate
or triaxial shapes. In order to explain the observed gradients, oblate models
of Sextans and Sculptor need to have a significant intrinsic ellipticity larger
than $0.47$ for Sextans and $0.46$ for Sculptor. The flattened oblate shape may
imply a significant anisotropy in velocity distribution in order to be
consistent with the lack of significant velocity gradients in these systems.
