Rare ancient star poses the question of modern cosmological models.
Astrophysics from the Federal Polytechnic school of Lausanne actively participated in the discovery of rare stars, very old and with a low content of metal. Being a messenger from the distant past, it will help scientists learn more about the early Universe.
“We made a great discovery, calling into question our understanding of the formation of the first generations of stars in the Universe,” says the researcher from the Federal Polytechnic school of Lausanne (EPFL) Pascal Jablonka.
Jablonka one of the founders of the study of Pristine. This is an international project dedicated to the search for the oldest stars with low metal content. In the course of the project and was discovered an extremely rare object. Found a star called Pristine 221 and it is among the ten stars with the lowest metal content in the halo of the Galaxy. Moreover, this is one of two unusual stars with almost no carbon. Article about the discovery is published in the journal Monthly Notices of the Royal Astronomical Society.
The Pristine team used a special narrow-band filter mounted on the telescope Canada — France — Hawaii (CFHT Telescope) for pre-selection of stars with the pristine atmosphere. This was followed by a detailed spectroscopic campaign with the help of telescopes Group them. Isaac Newton in Spain and the European southern Observatory in Chile. Researchers at EPFL Pascal Jablonka and Carmela lardo has formed one of three teams, along with the Paris Observatory, and the Canary Institute of astrophysics who led the spectroscopic analysis and measurement of chemical content, which led to the registration of this special star. They were able to demonstrate that the star really has very little heavy elements in its atmosphere.
“Most of the elements have indices from 10 thousand to 100 times lower than the Sun. In addition, stands out the detailed structure of its various elements. Then as usual the stars with very low metal content have a very high rate of carbon, the star is no longer the case. This makes it the second of its kind and an important messenger from the early Universe,” says Elsa, Starkenburg, a researcher from the American Institute of physics and lead author of the study.
“Previously, scientists believed that carbon is a necessary cooling agent, helping to implement a small fragmentation of the gas cloud from which the stars formed, leading to formation of low-mass stars in the Universe in the cosmological redshift, explains Pascal Jablonka. Having now two of the representatives of such old stars with a low content of carbon, we have to revise the existing model.”