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