The Orphan Stream is a long narrow stellar stream in the Galactic halo whose orbit is strongly tilted with respect to the Galactic disk and lies close to a distinct orbital plane (Belokurov 2007; Newberg 2010; Lux 2012; Koposov 2019). The stream's progenitor dwarf is fully dissolved or only weakly detected. Matching the Orphan Stream's detailed 3D track, precession, and thickness within a ΛCDM triaxial clumpy DM halo is challenging because halo shapes that fit other streams mispredict Orphan curvature and kinematics.
The standard model has the Orphan Stream resulting from random accretion of an independent dwarf galaxy onto a triaxial CDM halo. Different halo shapes that fit other streams (Sagittarius, GD-1) mispredict Orphan, indicating either modified halo physics or coincidental stream-orbit configurations that ΛCDM has no clean source for.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, the Orphan Stream plane is a shared-cascade-J inheritance signature. The Orphan Stream's progenitor was a cascade-debris fragment from the Milky Way's parent cascade-stream event, inheriting J that aligns with the broader Milky Way halo cascade-debris census and with the satellite-plane direction (P22, P25, P31, P32, P58, P59, P60).
The stream-orbit plane therefore aligns with the Milky Way's satellite plane (VPOS, recid 130) and with the cosmic-web filament direction in the local cascade-stream context. The interaction with the Large Magellanic Cloud that observations suggest is a downstream gravitational effect on the inherited orbital configuration, not the originating mechanism. Gravitational superposition (P50, P51, P52, P54) gives the apparent dynamics without requiring exotic CDM-halo shapes.
The same M3 framework that produces the MW VPOS (recid 130), the M31 satellite plane (recid 131), the Aquila Field of Streams (recid 135), and the broader cascade-stream J coherence accounts for the Orphan Stream plane. Halo shape need not differ between streams; instead, each stream inherits a related but distinguishable J vector from the same Milky Way cascade-stream parent context, and their orbital planes reflect this shared cascade-J inheritance with intrinsic variability set by cascade-stream substructure.
If precision Gaia + LSST + Roman Orphan Stream tracking finds the orbital plane uncorrelated with the Milky Way satellite-plane direction at greater than 3σ (no shared cascade-J inheritance signature), the M3 cascade-debris-plane explanation is refuted. The signature SCT prediction is Orphan Stream J alignment with VPOS + cosmic-web filament J direction.