Can anyone explain how flourine is created in the cosmos?

Question

It has something to do with white-dwarfs.

Answer 1

Any normal star which runs out of hydrogen can create fluorine by thermonuclear fusion, and strew it into space via a nova explosion.  This applies to all elements up through iron.

Answer 2

The responsible party is a so-called asymptotic giant branch star, which powers itself by two fusion reactions. The first, which occurs in an outer shell, converts hydrogen into helium via the CNO cycle, whereby carbon, nitrogen, and oxygen catalyze the hydrogen-to-helium reaction. The CNO cycle also converts carbon and oxygen into nitrogen-14.

The second fusion reaction occurs sporadically in a shell deeper inside the star, where the ash of hydrogen burning--helium--gets transformed into carbon. Helium-shell burning is unstable. When the helium shell ignites, it produces so much heat that the reaction causes a nuclear runaway, known as a helium-shell flash. When the reaction is over, convection in the star's outer envelope dredges the carbon up to the star's surface, changing a normal giant into a carbon star.

The same dredge-up also lifts fluorine to the surface. Because the hydrogen-burning CNO cycle produced nitrogen-14, this element is mixed with the helium ash. Once it's there, reactions during the helium-shell flash can transform it into fluorine-19. Normally that fluorine wouldn't stand a chance--it's surrounded by fluorine-fleecing helium nuclei apt to destroy it--but in this case the fluorine is forged faster than the helium can eliminate it and gets raised into the star's cooler upper levels. So when the star dies, it launches its fluorine-enriched atmosphere into space by way of a beautiful planetary nebula.