Some of the oldest stars in the universe have just been discovered. At the edge of our Universe and with an experienced team at the helm of the powerful James-Webb Space Telescope? Not. By undergraduates in decades old data and in our Milky Way.
Soon after big bang, about 13.8 billion years ago, the Universe contained almost only hydrogen and helium. Few other chemical elements. And this is one of the methods that astronomersastronomers can be used for rinsing the first stars of our Universe. Look for traces of strontium, bariumbarium or ironiron in spectraspectra fromstarsstars he collected telescopestelescopes.
In doing so, a team of MIT undergraduate students (Massachusetts Institute of Technology) just got hold of three stars that formed 12 to 13 billion years ago. Stars that were observed by the Magellan telescope ten years ago, but whose spectra have not been studied with this in mind until now. They are… in the halo of our own Milky WayMilky Way ! Only 30,000 light yearslight years countries.
in Monthly Notices of the Royal Astronomical Society (MNRAS), the researchers say how, by questioning the data from the Gaia missionthey realized that these stars are animated by a movementmovement retrograde. Realize that they are spinning in the wrong direction relative to the rest of the galactic disk. And even a halo. The sign, according to astronomers, to which these stars belonged, among the oldest in our Universe dwarf galaxiesdwarf galaxieswhich fell on ours Milky Way and then continued their momentum, even once integrated into our Galaxy. The reason why the researchers decided to call them “Small accreted star system” (SASS).
Other ancient stars to look for in the Milky Way
In the scientific literature, the team has since found traces of 65 other stars that also show low amounts of strontium and barium and that also appear to be involved in retrograde motion. And hundreds of kilometers per second. “It’s like they’re on the run!” We don’t know why.”comments Anna Frebel, prof physicalphysicalin MIT press release. The answer may lie in other ancient stars that researchers should now be able to find in our Milky Way using this simple method.