Primitive Stars Near Our Galaxy Found

Scientists using the European Southern Observatory's (ESO) Very Large Telescope (VLT), in Chile, managed to discover some of the most elusive stars around the Milky Way. These particular suns are very important, because they represent the primitive remnants of a far older Universe. Finding them proved to be extremely difficult, as they are completely mingled with other stars of a more recent origin, researchers at the Observatory say. The new investigation may also help us gain more knowledge about the early Universe, and the conditions that led to it developing the way it did.

“We have, in effect, found a flaw in the forensic methods used until now. Our improved approach allows us to uncover the primitive stars hidden among all the other, more common stars,” says the lead author of the study, ESO astronomer Else Starkenburg. According to accepted definitions, primitive stars are formed from materials that were created when the Universe was still in its infancy, more than 10 to 12 billion years ago. As a general rule, these old fireballs tend to feature less than one thousandth the amount of chemical elements that are heavier than hydrogen and helium, when compared to other stars.

This won them the name “extremely metal-poor” suns. The thing about these celestial bodies is that they are extremely rare, and that they can be observed best mainly around our galaxy. This happens because our massive Milky Way was formed by repeated mergers of much smaller, dwarf galaxies. “So far, evidence for [primitive stars] has been scarce. Large surveys conducted in the last few years kept showing that the most ancient populations of stars in the Milky Way and dwarf galaxies did not match, which was not at all expected from cosmological models,” says ESO expert Giuseppina Battaglia, who is a coauthor of the investigation.

The team developed a new computer model, which was used as a reference point for actual observations. The simulation gave them an idea of the differences they should be looking for while conducting measurements of nearby stars. The group realized that, by carefully comparing spectral readings from suns around the Milky Way, they could discern regular, metal-poor stars, from very old, extremely metal-poor ones. “Not only has our work revealed some of the very interesting, first stars in these galaxies, but it also provides a new, powerful technique to uncover more such stars. From now on there is no place left to hide!” Starkenburg concludes.