How to tell a gravastar from a black hole (also when it is rotating...)

Rotating gravastarsds 2 = −e ν(r) dt 2 + e λ(r) dr 2 + r 2 dθ 2 + r 2 sin 2 θ (dφ − ω(r)dt) 2ω(r) gives the dragging of the inertial frameAnisotropic energy momentum tensorT µν = (ρ + p t )u µ u ν + p t g µν + (p r − p t )s µ s νΩSlow rotation approximation (to first order in )u µ u µ = −1 , s µ s µ = 1 , u µ s µ = 0 ,u r = u θ = 0 , u φ = Ωu t ,u t = [ −(g tt + 2Ωg tφ + Ω 2 g φφ ) ] −1/2Ω is the angular velocityof the gravastar