VLT/SPHERE observations of MWC 758 spiral arms; (a) and (b) are the 2015 and 2019 scaled surface brightness Stokes ﹩{{ \mathcal Q }}_{\phi }﹩ images; (c) is the surface brightness ratio from dividing (b) by (a). In 2019, most of the southern region is more than twice the corresponding brightness of 2015; the northern region is less than half except for a brightened clump. The 184 mas diameter coronagraph used in 2019 blocks light in the central circular regions.
(The data used to create this figure are available.)