8,292 stellar streams discovered in Milky Way

Artist’s impression of generic stellar streams in the Milky Way.
Image credit: NASA/JPL-Caltech/R. Hurt, SSC & Caltech

A group of scientists recently discovered 8,292 stellar streams in our galaxy Milky Way, all named Theia.

A stellar stream is a group of stars in a linear pattern orbiting a galaxy which was once a dwarf galaxy or globular cluster that has now been ripped apart and extended out along its orbit by tidal forces.

Among all newly discovered Theia stellar streams, Theia 456 has a special place.

After going through data collected by Gaia Space Telescope, scientists found that Theia 456’s all 468 stars were born at the same time and are moving in the same direction across the sky.

According to scientists, mostly stellar clusters are formed together. Theia 456 is special as it is not a small group of stars together, rather it’s long and stretched out. There are very few such streams that are young, nearby and so widely scattered.

For long scientists knew that stars form in groups and most known clusters are of spherical shape. But lately they have started finding new patterns in the sky.

Journey Through The Universe

It is thought that these long strings of stars were tight clusters once. But gradually got torn apart and stretched by tidal forces.

Theia 456 stretches more than five hundred light years across. And since it resides within our galaxy’s galactic plane, so it is easily lost within the Milky Way’s backdrop of four billion stars.

Scientists found most stellar streams elsewhere in the Universe by pointing telescopes away from our galaxy.

To identify and examine these structures is a big data science challenge for scientists. In order to locate these structures, they used Artificial Intelligence (AI), which went through huge stellar datasets.

Then scientists developed algorithms to cross reference those data with pre-existing archive of documented star’s iron abundances.

They found that the four hundred and sixty eight stars within Theia 456 are similar in iron abundances. This implies that about hundred million years ago, all these stars probably formed together.

In order to add more evidence to this finding, scientists studied a light curves dataset, which records how star’s brightness changes over time.

By this, scientists can measure how fast the stars are spinning. Stars of the same age should display a distinct pattern in their spin rates.

By the help of NASA’s Transiting Exoplanet Survey Satellite (TESS) and Zwicky Transient Facility, scientists were able to ascertain that the stars in the stellar stream Theia 456, stars do have the common age and are travelling together in the same direction.

Both TESS and Zwicky Transient Facility produced light curves for stars in Theia 456.

As per scientists, if we can track the movement of stars, then we can also track where these stars came from. And as scientists backtracked these stars, they appeared closer and closer together. This made them think that all Theia 456 stars were born together and have a common origin.



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