Observed (black dots) and synthetic spectra of 2M00044180 around the two Rb I lines at 7800.250 Å (left panel) and 7947.612 Å (right panel). The synthetic spectra were computed for A(Rb)=−∞ (gray line) and for the final abundance from Table 2 (red line), given by the average abundance over the lines. The red shaded area corresponds to abundance variations within the amount of the standard deviation.