Stardust found in ancient extraterrestrial meteorite is older than the Sun

A clue from before our Sun was born has been left behind by a recently discovered type of star.

Research led by Western Australia’s Curtin University has used a unique method to analyse a dust particle found in an extraterrestrial meteorite.

Usually, material in meteorites comes from our solar system. This tiny, rare particle, however, has its origins from a time long before our Sun and the planets which orbit it were formed about 5 billion years ago.

These “presolar” grains have specific chemical signatures that show they were created by stars that came before our Sun.

“These particles are like celestial time capsules, providing a snapshot into the life of their parent star,” says Dr Nicole Nevill, lead author of a study published today in the Astrophysical Journal. “Material created in our solar system have predictable ratios of isotopes – variants of elements with different numbers of neutrons. The particle that we analysed has a ratio of magnesium isotopes that is distinct from anything in our solar system.”

Nevill took part in the research as part of her PhD studies at Curtin. She now works at the Lunar and Planetary Science Institute in collaboration with NASA’s Johnson Space Centre.

The team analysed the particle using atom probe tomography. This technique allows scientists to create a map of the different elements and their isotopes within a sample on the atomic scale.

“The results were literally off the charts. The most extreme magnesium isotopic ratio from previous studies of presolar grains was about 1,200. The grain in our study has a value of 3,025, which is the highest ever discovered,” Nevill says. “This exceptionally high isotopic ratio can only be explained by formation in a recently discovered type of star – a hydrogen burning supernova.”

“Hydrogen burning supernova is a type of star that has only been discovered recently, around the same time as we were analysing the tiny dust particle,” adds co-author Dr David Saxey from Curtin. “The use of the atom probe in this study, gives a new level of detail helping us understand how these stars formed.”

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