Toothpaste fluorine formed in stars

August 21, 2014
The Sun by the Atmospheric Imaging Assembly of NASA's Solar Dynamics Observatory. Credit: NASA


Fluorine can be found in everyday products such as toothpaste and chewing gum. However, the origins of the chemical element have been somewhat of a mystery. There have been three main theories about where it was created. The findings now presented support the theory that fluorine is formed in similar to the but heavier, towards the end of their existence. The sun and the planets in our solar system have then been formed out of material from these .

"So, the fluorine in our toothpaste originates from the sun's dead ancestors", said Nils Ryde, a reader in astronomy at Lund University.

With doctoral student Henrik Jönsson and colleagues from Ireland and the US, he has studied stars formed at different points in the history of the universe to see if the amount of fluorine they contain agrees with the predictions of the theory.

By analysing the light emitted by a star, it is possible to calculate how much of different elements it contains. Light of a certain wavelength indicates a certain element. In the present study, the researchers used a telescope on Hawaii and a new type of instrument that is sensitive to light with a wavelength in the middle of the infrared spectrum. It is in this area that the signal is found in this case.

"Constructing instruments that can measure infrared light with high resolution is very complicated and they have only recently become available", said Nils Ryde.

Different chemical elements are formed at high pressure and temperature inside a star. Fluorine is formed towards the end of the star's life, when it has expanded to become what is known as a red giant. The fluorine then moves to the outer parts of the star. After that, the star casts off the outer parts and forms a planetary nebula. The fluorine that is thrown out in this process mixes with the gas that surrounds the stars, known as the . New stars and planets are then formed from the interstellar medium. When the die, the interstellar medium is enriched once again.

The researchers are now also turning their attention to other types of stars. Among other things, they will try to find out whether fluorine could have been produced in the early universe, before the first red giants had formed. They will also use the same method to study environments in the universe that are different from the environment surrounding the sun, such as close to the at the centre of the Milky Way. There, the cycle of stars dying and new ones being born goes considerably faster than around the sun.

"By looking at the level of fluorine in the stars there, we can say whether the processes that form it are different", said Nils Ryde.

Explore further: Explainer: What are stars?

Related Stories

Sun-like stars reveal their ages

July 10, 2014


Lives and deaths of sibling stars

July 23, 2014


Recommended for you

Ceres image: The lonely mountain

August 25, 2015


Dawn spacecraft sends sharper scenes from Ceres

August 25, 2015


New Horizons team selects potential Kuiper Belt flyby target

August 29, 2015



Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Aug 21, 2014
5 / 5 (2) Aug 21, 2014
Don't we use fluoride in toothpaste? Fluorine is a different animal

Fluoride is just the anion of fluorine.
5 / 5 (2) Aug 21, 2014
Which element doesn't? We are star scavengers.


Click here to reset your password.