Profile of coefficients τ_ii/h² and τ_ij/h²,(j ≠ i) in a polytrope of index n = 5/2 fitted with 20   000 particles (model F₁ of Table 2). The distance to the center is normalized to the radius of the polytrope, R_s. The analytical value of τ_ii/h² is also given (horizontal dashed line corresponding to β = 1). Basically, all the star interior has a value β ≥ 0.95, while beyond a radius R_s − 2h_s (where h_s is the smoothing length close to the surface) the value of β rapidly declines (see Sect. 2.3 for the definition of β).