Astronomers have discovered three "cosmic Methusalems" from the earliest years of the universe. These unusual stars are about 13 billion years old and experts assign them to the first generations of stars after the "dark ages." The chemical qualities of these extremely rare stellar bodies enable new insights into the events that must have led to the origins of the stars. The first stars have been assumed to be high-mass and to shine especially brightly. However, the latest observations point to hitherto unknown phenomena in the young universe, allowing for the emergence of much smaller stars. An international team, including researchers from the Centre for Astronomy of Heidelberg University (ZAH), has discovered three "cosmic Methusalems" from the earliest years of the universe. These unusual stars are about 13 billion years old and experts assign them to the first generations of stars after the "dark ages." The chemical qualities of these extremely rare stellar bodies enable new insights into the events that must have led to the origins of the stars. The first stars have been assumed to be high-mass and to shine especially brightly. However, the latest observations point to hitherto unknown phenomena in the young universe, allowing for the emergence of much smaller stars. This conclusion is suggested by analyses in part conducted at the State Observatory Königstuhl and at the Institute of Theoretical Astrophysics, both of which belong to the ZAH.

The universe emerged approximately 13.8 billion years ago through the big bang. The initially extremely hot gas of the "explosion cloud" expanded and grew colder and colder. As the cosmic expanses were completely empty of stars at the time, scientists talk of the "dark ages" of the universe. About 400 million years after the big bang, the first stars formed out of the gases created by the explosion. Due to the chemical composition of the initial gases -- mainly hydrogen, helium and traces of lithium -- the stars' mass must have been 10 to 100 times greater than that of the sun, and therefore they must have emitted an extremely brilliant light. They rapidly exhausted their nuclear fuel and so these stars only shone for a few million years. They disintegrated in gigantic explosions, during which heavy chemical elements were released and "recovered" by subsequent stellar generations. An exact chemical investigation of this second generation of stars can enable conclusions to be drawn regarding the properties of the very first stars.