The Webb Telescope reveals that the strange remnants of the Milky Way are more than they seem

A strange group of stars nearby The core of the Milky Way The remains may be something much more complex than previously thought.

They call it this space The Terzan 5 region, named after astronomer Agop Terzan, who discovered it in 1968. At first glance, it looks like a dense ball of ancient stars, which is the type astronomers usually call Spherical block. But new data from NASA‘s James Webb Space Telescopeas well as two decades of Hubble observations, show that it is much more than that.

Although globular clusters typically contain only one old star cluster, Terzan 5 appears to have at least four generations. The first stars were born 12.5 billion years ago, followed by waves dating back approximately 4.7, 3.8, and 2.5 billion years.

The chemistry within the cluster also indicates at least two types of… Supernovae It happens inside him. Early on, massive stars exploded and enriched the system with heavier elements. Later, the so-called Type Ia supernovae — White dwarfs That exploded – added more iron. Over time, levels of lighter elements, such as oxygen and magnesium, decreased. This pattern fits a system that continues to recycle gas and form new stars.

For astronomers, these clues suggest that Terzan 5 started life much larger, then dumped most of its stars into space. The bulge of the Milky WayThe dense swarm of stars around the center of the galaxy. By reconstructing its missing mass, and testing whether it is hiding Dark matter Or a Central black holeMapping how the galaxy is pulled apart, researchers hope to use Terzan 5 as a kind of Rosetta Stone to study how galaxies build their central regions.

R. said. “This is kind of like a galaxy in a bottle,” said Michael Rich, a research astronomer at the University of California, at the 248th meeting of the American Astronomical Society in Pasadena, California.

Terzan 5 can accommodate about 3,000 people Light year From the center of the Milky Way, in the crowded region that astronomers call the bulge.

Terzan 5 resembles a piece of material that helped build the central bulge of the Milky Way, so the research team now calls it a “fossil bulge fragment,” said Francesco R. Ferraro, lead researcher on the observations at the University of Bologna in Italy. statement.

By comparing nearly two decades of images, the researchers tracked how individual stars drifted across the sky. The real members of Terzan 5 move together, in the foreground and background The stars move around in different ways.

“We look at the group as if it were a flock of birds, and basically, there are these birds flying together in the flock, but there are a lot of other birds that are kind of flying randomly,” Rich said. “Other birds are stars in the galactic bulge.”

Now the team wants to bring back his life story. Today, Terzan 5 weighs about 1 to 2 million times the planet’s mass sunsimilar to a huge block. But the team believes the cluster started life with a much larger mass — perhaps the equivalent of a billion suns — and slowly lost most of its stars due to the swelling of the Milky Way. The team plans to use Webb to count low-mass stars in Terzan 5, and estimate how strongly the galaxy is stripping away stars over time.

Astronomers used new data from NASA’s James Webb Space Telescope, left, as well as two decades of Hubble Space Telescope observations to study Terzan 5.
Credit: NASA illustration

They also see hints that something unseen may be lurking within. Previous measurements have indicated that stars along the outer edges of Terzan 5 are moving faster than visible material comfortably explains. This tension helped motivate Webb’s study in the first place.

“We are currently performing a detailed analysis to try to see if we can explain this movement by a group of low-mass stars, or if we need something else,” Rich said. “This other object is likely the first globular cluster to host dark matter.”

Another idea refers to A Huge black hole In the center, which would reveal themselves through fast-moving stars near the core. So far, the team has not seen clear evidence of this.