Spectral index of L1527 as measured along directions of the outflow (violet) and envelope (green), cavity walls (orange). The total α is also plotted (gray). The way the uv-coverage has been sampled is shown in the upper inset (B7 as an example). The scarce uv-coverage of the ACA B7 observations cause some bins to be undefined at the short baselines, hence the gaps. In all cases, α is only computed starting from 20 kλ.