A New Study May Resolve a Long-Standing Puzzle about Meteoritic Stardust
Meteorites contain stardust: tiny dust particles that formed in ancient stars and were part of the original building blocks of the Solar System. Studies of one class of stardust－oxygen-rich grains like silicates and aluminum oxide－revealed a long-standing puzzle. Intermediate-mass stars (roughly six times heavier than the Sun) are seen by infrared telescopes to produce huge amounts of dust in the Galaxy, but we had not been able to find any dust from these stars in the Solar System meteoritic record.
A new measurement of an important nuclear reaction that occurs in such stars may have resolved the issue, as reported in a new paper co-authored by Larry Nittler published in the new journal Nature Astronomy this week. The work, titled "Origin of meteoritic stardust unveiled by a revised proton-capture rate of 17O," was led by astrophysicist Maria Lugaro from the Konkoly Observatory in Hungary.Left: A Hubble Space Telescope image of planetary nebula NGC 5189; a cloud of dust particles formed at the end of a star’s life. Right: Electron microscope image of a presolar Al2O3 stardust grain extracted from a meteorite. This grain was part of a planetary nebula >4.6 billion years ago and became part of our Solar System.; scale bar is one millionth of a meter.
The measurement, performed at an underground laboratory in Italy called LUNA, revealed that a rare type of oxygen, known as oxygen-17, is destroyed more quickly than previously believed. Armed with this new destruction rate, the team found that the expected oxygen composition for the heavy stars actually matches some of the meteoritic stardust grains previously thought to come from lower-mass stars, potentially resolving the mystery of the missing grains.
“This result indicates that the Solar System sampled a typical range of stellar dust grains when it formed, and moreover is a great example of how different scientific fields, in this case, nuclear physics, astrophysics theory and laboratory study of meteorites can come together to advance our understanding of the cosmos,” says Nittler.
Written by Larry Nittler // February 2, 2017
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