The Sculptor dwarf spheroidal is the best-dissected of the Milky Way's classical satellites, and the dissection keeps returning awkward anatomy. The galaxy is noticeably flattened in projection; it hosts at least two chemically and kinematically distinct stellar populations, a centrally concentrated metal-rich component and an extended metal-poor one; and the combined line-of-sight and proper-motion kinematics favor a cored inner mass profile with at most mild rotation (Battaglia et al. 2008; Walker and Penarrubia 2011).
Each property pinches the standard picture from a different side. The cored profile contradicts the steep cusps generic to low-mass CDM subhalos, the dwarf-scale face of the core-cusp problem. The flattening lacks a driver: a dispersion-supported system in a spherical halo should relax toward roundness, and Sculptor's mild rotation is insufficient to flatten it centrifugally. And the formal modeling escape, that inferred profiles and shapes are degenerate with unknown inclination and velocity anisotropy, cuts both ways, making the model unfalsifiable in exactly the regime where its predictions are most distinctive (Breddels and Helmi 2013; Read et al. 2019). Two populations sharing one halo while exhibiting different scale lengths and dispersions only tighten the joint constraint.
The standing makes Sculptor the precision battleground for dwarf dark matter profiles: the system with the best data, the cleanest multi-population leverage, and the most stubborn refusal to look like a CDM subhalo.