An attempt to determine stellar Lyman-alpha emission-line fluxes for F stars with different metal abundances

We have studied stellar Lyα fluxes for F stars of different metal abundances which are presumably older the more metal deficient they are. We describe the correction procedure for the geocoronal emission and our estimate of the correction for interstellar absorption. We find stronger than average Lyα emission for the Hyades stars and for the two close binaries HR 1354 and α Tri. <P />For single non-Hyades stars we find increasing Lyα emission for decreasing metal abundances. Assuming that the total hydrogen emission, including H and H - continua and Lyman lines, is twice the amount of the Lyα emission, and that the metallic emission, including Mg II h and k and Ca II H and K lines, is 4 times the Mg II k emission, we find that the total chromospheric energy loss, and therefore also energy input, is nearly independent of metal abundance and therefore presumably independent of age, for ages larger than a few times 10<SUP>9</SUP> years.