For a long time, scientists have been trying to find ways to estimate the age of a star. But according to a BBC report, there is a team of US astronomers who was finally able to confirm an accurate way to say how old a star is: by the speed of its spin.
It was the 1970s when the idea of measuring the spin of a star in order to calculate its age was first announced; in 2003, it got the name of “gyrochronology”, but scientists did not have enough data to back-up their formulas and theories. The trouble was that the size, mass, brightness and temperature of a star does not change considerably during its life, therefore do not offer any insight about its age.
The results showed that a cool star rotates a lot faster when it’s young, but it gets slower and slower as the star grows older, as senior author Dr Soren Meibom explains. The spin of a star also depends on its mass, therefore bigger, heavier stars will spin faster than smaller ones.
As of today, a team of US scientists has been able to measure accurately the speed of 30 stars. The main source of data is the very sensitive Kepler space telescope, orbiting Earth since 2009; astronomers can now estimate a star’s age to within 10%.
Accumulating data is a slow process in this field, but so far, it has shown that a lot of stars seem to fall in this pattern. Unfortunately, researcher Ruth Angus, of the University of Oxford, explains that we do not know yet how reliably stars fall onto this new found relation.
Studying this cluster of stars will certainly help understand and prove gyrochronology as a certified method, and also finding out if it’s valid. This method of demonstrating the star’s age applies to “cool stars” — that is, suns which resemble our own in size. These stars form the majority in our galaxy, and the known data also shows that they have a long life-span.
The search for extraterrestrial life in other solar systems is one other reason why discerning stars’ age is especially important. Upon finding a reliable way to determine star’ ages, astronomers could improve the search for planets orbiting stars at least as old as our Sun, which would be able to support and encourage life.
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