The Mystery of the Ancient Star Swarm M92 ✦
In globular cluster M92, stars split into two groups. The second group is enriched in sodium and, as it turns out, contains more iron—meaning the cluster held onto material from supernova explosions that occurred after the first stars were born. Think of it like a layered cake, where the top layer got an extra filling: later stars absorbed elements from earlier cosmic blasts. How long did this "baking" take?
Globular clusters are vast swarms of ancient stars. In M92, astronomers used precise brightness measurements to select similar stars, and then broke their light into colors to determine their chemical composition. It turned out that stars born later contain slightly more iron — like adding seasoning to a soup after the first batch and cooking a second batch from the same broth. Previously, it was thought that after supernova explosions, all the gas escapes. But M92 shows: the pot was covered. This revealed that at least three million years passed between generations — the time needed for a massive star to explode, as predicted by Fritz Zwicky. The processes of nuclear synthesis, creating new elements inside stars, were first described by Hans Bethe. Moreover, traces of rare elements were found in the first 'batch' of stars, possibly born from the merger of neutron stars — superdense remnants. Now it's clear: old globular clusters hold a memory of the first few million years, and this is key to understanding star formation and the entire stellar evolution.
🎯 The M92 cluster is over 12 billion years old — it was born when the Universe was just 2 billion years old. To this day, its stars hold memories of those infant explosions.