AMBER visibilities, SED, and best-fit temperature-gradient model of V921 Sco. a) wavelength-dependent calibrated visibilities (baselines 31 m, 63 m, 95 m from top to bottom) and temperature-gradient model fits (dashed lines, see Sect. 3.2). b) available ground-based SED data (red points; Borges Fernandes et al. 2007), Spitzer spectrum (green line), and the model fit (black line). The inset shows the K-band intensity distribution of the best-fit temperature-gradient model (log scaling). The white dashed lines indicate the dust sublimation radii predicted by the size-luminosity relation for the temperatures of 1500 K (outer ring) and 2000 K (inner ring) using the stellar parameters reported by Borges Fernandes et al. (2007).