Fig. 4: The Luminosity Function of NGC1818 and its age distribution.

a Observed Luminosity Function of main-sequence stars of NGC1818 is shown in solid black, while the uncertainties are indicated by the dark-grey shaded regions. The blue line corresponds to the best-fit LF, with uncertainties indicated by the azure-shaded regions. b As in (a), the black line indicates the observed LF, whereas the red line represents the LF inferred from the age distribution inferred from the eMSTO (panel c of Fig. 2). The y-axis of (a) and (b) have been normalized so that the height of the turn-on peak corresponds to 1. c Age distributions of NGC1818 inferred from the turn-off (red) and the turn-on (blue). The shaded regions represent the inferred uncertainties. The top-left inset shows the mean, FWHM and full width, in Myr, of the least-square best fit Gaussian function.