Astronomers have discovered a mysterious stream of ancient stars on the farthest edges of the galaxy: they may very well be the last of their kind, unlike a strange stellar race we’ve never seen before.
This unusual collection of stars – called the ‘Phoenix Stream’, after the Phoenix constellation in which they appear – is known as a stellar stream: a long chain of stars that existed in a circular form, called Known as spherical clusters.
Such clusters can be torn by the gravitational forces of the galaxy, in which case their spherical form is distorted, spreading into a ghostly caravan of stars, orbiting a distant galaxy.
Above: The artist’s impression of the stellar current around the Milky Way.
Neither stellar streams nor spherical clusters are new to science, but there is something about the Phoenix stream. Its chemistry is different from any spherical cluster we have seen, almost the same as it is not here.
Astronomer Kylar Kuhn of the Lowell Observatory in Arizona explains, “We can do a lot by measuring the different types of chemical elements in which we detect them, such as the relationship we have to a person’s ancestors through our DNA Can detect. “
“It’s almost like finding someone with DNA that doesn’t match another person, living or dead.”
The Milky Way has about 150 known spherical clusters, all of which exist in what is called a galactic halo – a thin spherical structure covering a relatively flat galactic disk, where most of the galaxy’s stars are otherwise conjugated.
Outside the halo, however, many stars still gather inside circular clusters. Each cluster can contain hundreds of thousands of stars, and observations of clusters in the Milky Way show that all clusters exhibit a certain stability in their stellar chemistry: the stars in the cluster are enriched with ‘heavy’ chemical properties that Occur more extensively than hydrogen and helium.
After the Big Bang, the theory states that all the gases in the universe were made up of either hydrogen or helium, which in turn formed the first stars of the universe. Other elements, such as oxygen, carbon, and magnesium, became possible much later through the fusion mechanisms of later generations of stars.
The chemical legacy of all those later fusion mechanisms is all around us, as a certain proportion of heavy elements have been observed in all of our galaxy’s spherical clients. That is till now.
This chemical threshold – called the metal floor – is not followed by the Phoenix stream, which exhibits less heavy elements in its strands than we thought were theoretically possible for such a celestial structure.
“This stream comes from a cluster that, by our understanding, should not exist,” explains astronomer Daniel Zucker of Macquarie University in Australia.
Or at least, it shouldn’t exist now, May be another way of applying it.
Phoenix Stream’s observations conducted by an international team of researchers as part of the Southern Stellar Stream spectroscopic survey collaboration showed that its “metal abundance is well below the empirical metallicity floor”, the authors state in their new study.
Until now, the metal floor was a useful way of classifying the scientific continuum seen in all present-day circular clusters. It still is, as it happens – but the Phoenix Stream is not currently a circular cluster.
The team feels that it may be the only survivor: an astronomical remnant of a bygone era in the early universe, when stars made their light in different ways.
“One possible explanation is that the Phoenix Stream represents the last of its kind, the remains of a population of spherical clusters that originated in fundamentally different environments to those we see today,” of Carneg Observatories in Pasadena Says astronomer Ting Li.
Of course, a lot of questions remain. If the Phoenix Stream is a remnant of the early Universe, is it the only one? Do others exist, who are hidden in the vastness of the galactic aura?
“In astronomy, when we find a new kind of object, it shows that there are more of them,” says astronomer Jeffrey Simpson of the University of New South Wales (UNSW), Australia.
If other older travelers are still on the trail, we don’t have forever to find them. Like spherical bunches, stellar currents are not immortal things. Once they are pulled into a string of stars, it is only a matter of time before they disintegrate, and spread to the entire galaxy.
“Who knows how many relics like the Phoenix Stream can be hidden in the Milky Way’s halo?” German astronomer JM Diederich Kruijssen of Heidelberg University, who was not involved in the study, but has written a comment on it.
“Now that the former has been found, the hunt continues.”
The findings are stated in Nature.