Scientists finally unlock the key to correctly aging stars: measuring how fast they spin

Astronomers will be able to use this knowledge to correctly estimate the age of stars in the universe, which is similar in importance to aging fossils in the study of evolution.

Scientists can reliably determine just how old a star is from how fast it is spinning, according to new research.

Although scientists have long known that stars slow down over time, there was not much data to allow for more exact calculations, but a team in the United States has measured the spin speed of stars that are at least one billion years old, and they are finding that their calculations are correct, according to a BBC report.

Using this new-found knowledge, astronomers will now be able to estimate the age of star with a margin of error of just 10 percent, according to the study which was published in the journal Nature.

Estimating the age of a star is crucial, similar to the importance of dating fossils in studying evolution. Astronomers used the method on “cool” stars, which are suns that are similar to ours in size or smaller, which the galaxy is filled with. They tend to act as “lamp posts,” according to senior author Dr. Soren Meibom from the Harvard-Smithsonian Center for Astrophysics. They are also where scientists expect to find most earth-like planets.

It is helpful to determine the age of these stars because most of them don’t change their core attributes over time, maintaining the same temperature, mass, brightness, and size throughout its life — making them difficult to age through other methods.

The idea of measuring the star’s spin had been proposed decades ago, and was called “gyrochronology” in 2003. Scientists noticed that a cool star tends to have a very fast spin when it is early in its development, almost like a top spinning on a table.

The problem with this, however, is it is often difficult to see the spin on the star. Astronomers tend to use sun spots to measure it, but that becomes more difficult with older stars, as they have fewer and smaller sunspots.

Melbom’s team used the Kepler space telescope to make the observations. They examined spin speeds for 30 stars in one cluster that they knew was 2.5 billion years old. Before that, we only knew how very cool stars acted in young clusters that were only a little more than a half a billion years old. Other than that, all scientists had to go off of was our own sun, which is about 4.6 billion years old.

But now, with this new data, scientists can more reliably estimate the age of stars far from us in much older galaxies.