Bottom line: Astronomers say that the cluster known as Terzan 5 is fossilized remnant of the early Milky Way.
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And the similarities could make Terzan 5 a fossilised relic of galaxy formation, representing one of the earliest building blocks of the Milky Way.
Terzan 5, a stellar cluster with an unusual mix of stars that indicates it was a primordial building block of the Milky Way.
A cluster of stars at the heart of the Milky Way has survived violent star formation processes, becoming as a galactic “fossil” from the birth of the galaxy. Some of the stars seem to be among the most ancient in the galaxy, giving scientists a chance to observe how some of the galaxy’s first stars are existing alongside newcomers.
“The oldest population of stars is 12 billion years old – nearly the age of the Universe”. Most orbit the galaxy’s center in a vast halo like moths whirring around a bright light.
This assumption is strengthened by the original mass of Terzan 5 necessary to create two stellar populations: a mass similar to the huge clumps which are assumed to have formed the bulge during galaxy assembly around 12 billion years ago.
He said it was thought that some globular clusters such as M54 – also found in the constellation of Sagittarius – may have been the core of dwarf galaxies that were substantially bigger when they were younger and had the stars ripped off the outside.
The team scoured data from the Advanced Camera for Surveys and the Wide Field Camera 3 on board Hubble, as well as from a suite of other ground-based telescopes. Not only do they show a large gap in age, but the differ in the elements they contain.
This requires the Terzan 5 ancestor to have large amounts of gas for a second generation of stars and to be quite massive.
The Universe Today reports that Terzan 5 is a paradigm for the title of “living fossil” from the ancient days of Milky Way.
This large ball of preserved gas is exactly the kind of clump of material that astronomers believe merged into the galactic bulge at the center of the Milky Way some 13 billion years ago.
While the qualities of Terzan 5 are rare for a globular cluster, they are somewhat common in the stellar population located in the galactic bulge, the closely-packed central area of the Milky Way. And it’s unlike any globular cluster they have ever seen. An global team of astronomers made the discovery, calling Terzan 5 a rare relic of the early Milky Way. Later, the cluster, which held onto some of its remaining gas, experienced a second burst of star formation. The information could help to explain how galaxies are formed, and bring new insight into the history of the over 13 billion-year-old Milky Way galaxy, which, of course, houses our solar system.
“Terzan 5 could represent an intriguing link between the local and the distant universe – a surviving witness of the galactic bulge assembly process”, Ferraro said in the statement.
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The Milky Way on a late September night offers an opportunity to contemplate the grand form of the galaxy. In other words, whatever is happening within Terzan 5 is a much more recent view of what may have been happening during a time in the universe’s past when galaxy formation was rampant. In the near-past, which records humanity’s comings and goings, details are often forgotten or lost.
