A globular cluster’s stellar stream remnant under the metallicity floor.
In 98.5 percent of the Sun, hydrogen and helium are the two light chemical elements. The other 1.5 percent of the Sun is made up of more heavy elements like carbon, oxygen, and iron.
The amount of these heavier elements present in a star is referred to as its ‘metallicity,’ and it differs from star to star in its abundance. Now we know that our galaxy is home to a unique stellar structure made up of stars with very low metallicity. These stars have a lot of heavy elements in them, almost 2,500 times lower than that of the Sun.
This is much below any known star structure in the Universe.
The stars in this cluster are all members of a stellar structure in the Milky Way known as C-19. It not only challenges our current understanding and models of the formation of these stellar groupings, which rule out the existence of structures composed solely of such stars, but it also provides a unique and direct window into the very earliest ages of star formation and the development of stellar structures in the very distant past.
Due to the fact that heavy elements were created by multiple generations of big stars, the C-19 stars had a relatively low metallicity, indicating that they formed shortly after the Universe was born.
The findings published today in the journal Nature were led by a CNRS researcher at the Strasbourg Astronomical Observatory (CNRS / University of Strasbourg) and including scientists from the Galaxies, Stars, Physics and Instrumentation Laboratory (Paris Observatory – PSL/CNRS) and the J-L Lagrange Laboratory (CNRS / Côte d’Azur Observatory).
Source: Nature
Image Credit: N. Martin / Strasbourg Astronomical Observatory / CNRS; Canada-France-Hawaii Telescope / Coelum; ESA / Gaia / DPAC
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