Left panel: UV continuum slope β_obs measured inside the COS aperture between 1540 Å and 3330 Å. We add to this figure both the location of the COS aperture and the edge of the galaxy disk. While the disk exhibits a reddened UV continuum slope (with β_obs in the range [−2.60; −1.60]), each outflowing halo is characterized by a blued UV continuum. The β_obs values of each halo are well below the intrinsic slope β_int = −2.50 (see text for more details). Right panel: age map of the young stellar population of Mrk 1486, as derived by SED fitting of the HST observations on a pixel-by-pixel scale. The field of view is the same as in Figs. 2 and 4. The green dashed circle corresponds to the region covered by the HST/COS aperture, and the blue dashed lines indicate the edge of the galaxy disk. We represent here the stellar age on a logarithmic scale. We find approximately the same age for the young stars throughout the disk of the galaxy, with a mean age of 3.02 ± 0.20 Myr.