This element was first isolated by H. Moissan in Paris in 1886. Its name comes from the Latin fluere (to flow).

Ionization energies
FI 17.4 eV, FII 35.0 eV, FIII 62.7 eV.

F in stars
The presence of some faint F II lines in B-type stars has been announced, but not confirmed. Beals (1951) observed absorption lines of FII in P Cyg.

The best evidence for the presence of F in stars is the molecule HF, which is present in the sun and in K 5III to M 4III stars (Jorissen et al. 1992).

Behavior in non-normal stars
In S, SC and C stars the HF feature is enhanced, which leads to an overabundance of F by up to 0.6 dex (Jorissen et al. 1992).

F has only one stable isotope, namely F19, and five short-lived ones.

F19 is produced by hot hydrogen burning.

Published in "The Behavior of Chemical Elements in Stars", Carlos Jaschek and Mercedes Jaschek, 1995, Cambridge University Press.