Age of Stars: By their Spin, We Shall Know Them

Cluster of stars
A giant stride has been made in the study of the age of stars. Astronomers find that the actual age of a star can be calculated by the speed of its spin. It is found that younger stars spin faster than the older stars.


For the first time, a US team has now measured the spin speed of stars that are more than one billion years old - and it matches what they predicted.
The finding resolves a long-standing challenge, allowing astronomers to estimate a star's age to within 10%.
The work was presented in Seattle at a meeting of the American Astronomical Society and also appears in the journal Nature.
This is applicable to the “cool starts” – suns about the size of our own sun, or even smaller. They are mostly available in our galaxy.
Dr. Meibom from the Harvard-Smithsonian Center for Astrophysics called them the lamp posts
"They act as lamp posts, lighting up even the oldest parts of our galaxy." 
Cool stars also host the vast majority of earth-like planets that we have spotted in the distance.
The study of star spins dates back to 1970 with the name, Gyrochronology.
"A cool star spins very fast when it's young, but just like a top on a table it gets slower and slower as the star grows older," Dr Meibom said.
Granted is the fact that it is difficult to see a star spin. Astronomers takes recourse to the sun spots on the stars to tell the spinning.
Measuring the younger stars is easier because they have larger sun spots; older ones smaller sun spots. These makes studying their spinning more problematic.
A young star
A Young Star with Large Sun Spots
Kepler space telescope, which has been trailing Earth around the Sun since 2009 got images used by this team in measuring about 30 stars in a cluster of 2.5 billion years.
An older star
Older Stars have Smaller Sun Spots
A PhD student, Ruth Angus who researches gyrochronology at the University of Oxford, said the results were "a really big deal" for the field.
"More evidence has been slowly accumulating that lots of stars do seem to follow this pattern, but how reliably stars fall onto this relation is a bit of an unknown," Ms Angus told the BBC.
"This cluster will certainly help with our understanding of how good gyrochronology is as a method, and how valid it is.
"It shows that these stars are doing what they're expected to do, and everything's peachy."



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