Astronomers from Switzerland, Ireland, and the United States have used a new telescopic technique to identify the mysterious stellar origins of fluorine: red giant stars.
Nebula NGC 6826, a diffuse collection of gas and other material, from which new stars and planets may be formed. Image: X-ray: NASA/CXC/RIT/J.Kastner et al.; Optical: NASA/STScI
Considering its chemical properties, fluorine is astronomically rare, and there are a number of reasons for this. Fluorine is not created by the typical nuclear fusion processes which create other elements within stars. When fluorine appears in stars, it is ephemeral, instantly pressure-cooked into oxygen thanks to the stars’ furnace-like interiors. And in space, any freely available fluorine often combines with hydrogen, the most abundant element. This interstellar reaction forms, you guessed it, maybe: hydrogen fluoride, or HF. And this is exactly what the researchers were searching for with their telescopes.
When stars are shining away, they are undergoing nuclear reactions with various elements. The light that emanates from these stars carries the signature of those reacting elements. For the first time, astronomers have used new equipment and hydrogen fluoride (HF) as a search target to detect the presence of stellar fluorine.
The researchers turned their Hawaiian-based telescopes towards nearby stars to measure their HF content. They found HF occurring specifically in stars of a particular age and size, known as ‘red giants’. These stars are red, enormous, and at the end of their lives. Though scientists did not know the ultimate genesis of fluorine, they had three different hypotheses. None of which had much supporting evidence until now.
The findings of the current study neatly support the idea that fluorine is created by these ol’ red giants. These stars have fluctuating innards that bring up fluorine to their exterior. And then, on their starry death beds, the aged stars swell and explode, sending their fluorine-bearing ejections throughout the neighbouring solar systems. Over billions of years this star matter cools and condenses, forming new stars and planets such as our own Sol and Earth. From here, humans mine it from the planet, refine it, disregard its ultimate origins, plop it in toothpaste, and then parade it about on TV as “the toothpaste that’ll give you that sparkling smile, just like the stars.”
Original Paper: http://iopscience.iop.org/2041-8205/789/2/L41