Astronomers spot giant stream of stars between galaxies

A group of researchers from around the world were shocked when they found a huge, very faint stream of stars between galaxies. This is the first time that a stream running between galaxies has been seen. Streams have been seen in our own galaxy and in galaxies close by. To date, it has been the largest stream found. The astronomers wrote about their results in the Astronomy & Astrophysics magazine.

Scientist Michael Rich used his small 70-centimeter telescope in California (United States of America) to make the first views. After that, the 4.2-meter William Herschel telescope (La Palma, Spain) was pointed at the area. The picture was then processed, and they saw a very faint stream that was more than 10 times the length of our Milky Way. The stream seems to be floating in the middle of the cluster setting and not connected to any one galaxy. It is known as the Giant Coma Stream by the scientists who study it.

"By chance, this huge stream crossed our path," says Javier Román, the lead expert. The University of Groningen in the Netherlands and the University of La Laguna in Tenerife, Spain, are both behind him. "We were studying halos of stars located around large galaxies."

The Giant Coma Stream's finding is amazing because it is a rather fragile structure in a place where galaxies are pushing and pulling each other away. "Meanwhile, we have been able to simulate such huge flows in the computer," says co-author Reynier Peletier from the University of Groningen in the Netherlands. That's why we think we'll find more of them. Case in point: if we search with the future 39-meter ELT and when Euclid starts collecting data."

As big antennas get better, experts hope to find more than just new giant streams. They also want to get a better look at the Giant Coma Stream. "We would love to observe individual stars in and near the stream and learn more about dark matter," adds Peletier.

One of the most well-studied groups of galaxies is the Coma Cluster. At about 300 million light-years from Earth, in the direction of the northern constellation Coma Berenices, it is home to thousands of galaxies. Fritz Zwicky, a Swiss scientist, showed in 1933 that the galaxies in the cluster move too fast if you only look at how much matter you can see. The dark matter that holds everything together must be real, he thought. We still don't know what dark matter is made of.