Envelope structure of a range of giant star models that share 600 R_☉. The top panel shows the density profile of the envelopes, while the center and lower panels show flow the Mach number and the density gradient that would be experienced by an inspiralling 1.33 M_☉ NS. For much of the stellar interior, mach numbers are moderate with density gradients of _ρ ≈ 1–2.5, representing substantial density inhomogeneity across the accretion radius. Spikes in the density gradient are seen in the deep interior at transitions in chemical composition.