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| galaxy Zwicky 18 |
Segue 1 differs from other dwarfgalaxies, such as I Zwicky 18, as it’s nolonger in a state of evolution
Galactic partnercould shed new
light on how theearly universe was composed
Segue 1, a dwarf galaxy that’s a satellite to the Milky Way and has been under
scrutiny by an international team of astronomers, has now been revealed to
be an ancient relic left over from the early universe.
The fossil galaxy, whose chemical composition was analysed to unravel
its history, is made up of a uniquely ancient composition. Not only that,
but the galaxy’s star formation wasn’t as cyclic as the galaxies we
see today, which form and die in a great supernova explosion, before
seeding nearby gas with the necessary elements to begin the process again.
According to researchers, Segue 1 gave up on its star birth at what would be
an early stage of development. “Our work suggests that Segue 1 is
the least chemically evolved galaxy known,” says the Carnegie Institution
for Science’s Josh Simon. “After the initial few supernova explosions, it
appears that only a single generation of new stars were formed and then for
the last 13 billion years the galaxy has not been creating [any].”
Since the galaxy has been preserved in a state of low iron-abundance,
among other heavy elements, and only seven stars in the galaxy are
actually in the red giant phase, Segue 1 offers unique information about the
conditions in the universe shortly after the Big Bang.
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