Astronomers have found a “mirror image” of the Milky Way billions of years ago
(ORDO NEWS) — Have you ever wondered what our Milky Way galaxy looked like at the beginning of its history?
Astronomers using the Webb Telescope (JWST) have discovered another galaxy that is almost a mirror image of our baby galaxy.
They call her “Sparkler”. This is because about two dozen brilliant globular clusters revolve around it. There are also several dwarf galaxies that have been swallowed up by the galaxy.
The JWST view shows Sparkler as he looked when the universe was only four billion years old, or about a third of the current age of the universe.
This means that this galaxy, like the Milky Way, began to form very early in cosmic history.
If Sparkler follows the same growth path as the Milky Way, through mergers and acquisitions of galaxies, then it should grow in the same way as the Milky Way.
In about nine billion years, it will look very much like our twin.
A distant, early proxy of our Milky Way
Sparkler is in the direction of the constellation Volan (in the sky of the southern hemisphere). This is quite far, with a redshift of z = 1.38.
This is about 9 billion light years, that is, several billion years after the Big Bang. Like the Milky Way, Sparkler did not emerge fully formed from space.
Both galaxies originated as “superdensities” of matter (like clouds of neutral hydrogen) in the early universe. Think of them as “seeds” of galaxies pulled together by gravitational pull.
Globular clusters were born in some of these clusters, probably shortly before the birth of the galaxy. This is why the stars in some globular clusters are older than their galaxies.
Then came the era of “mergers and acquisitions” when the infant Milky Way (and presumably Sparkler too) began to gobble up nearby dwarf galaxies. This is a big evolutionary step.
It is possible that at least half of the mass of our galaxy was formed as a result of these mergers. Over time, all the material coalesced into a spiral disk on which the Sun and most other stars exist today.
The future of sparklers compared to the Milky Way
Will the sparkler follow the same evolutionary pattern? way like the Milky Way? Judging by the JWST data, it will.
Although it is currently only a small fraction of the Milky Way’s mass – about 3 percent – this will change as it engulfs other, smaller galaxies.
Eventually, its mass will be equal to the mass of the Milky Way in the modern Universe.
This is very interesting because it gives astronomers a way to understand what happened as our own galaxy evolved.
“We seem to be seeing first hand the assembly of this galaxy as it builds up its mass – in the form of a dwarf galaxy and several globular clusters,” said Professor Duncan Forbes from Swinburne University in Australia.
He studied the galaxy and its clusters with Professor Aaron Romanowsky of San Jose State University in California.
“We are excited. thanks to this unique opportunity to study both the formation of globular clusters and the infant Milky Way at a time when the age of the universe was only 1/3 of its current age,” he said.
Forbes and Romanovsky used the JWST data to study the age and metallicity of several “sparks” (compact sources) in and around the Sparkler galaxy.
The goal was to study the metallicity of a number of compact star clusters surrounding Sparkler. The scientists wanted to see if they resembled younger versions of the Milky Way’s globules.
Clues to Sparkler’s early history in his globular clusters
JWST’s observations of Sparkler may also answer various questions. questions about globular clusters and their formation, according to Romanovsky.
“The origin of globular clusters is a long-standing mystery,” he said. “We’re thrilled that JWST can look back and see them as young adults.”
It turned out that the Sparker clusters have a striking resemblance to some of the globules of the Milky Way.
Some of them appear to have formed very early, and the stars are quite rich in metals. This seems to indicate a very rapid process of chemical enrichment in the early universe.
A couple of clusters contained stars that were slightly older and poorer in metals than the other clusters. They probably belong to a low-mass satellite galaxy that falls into Sparkler.
This scene is very reminiscent of the Milky Way’s history of mergers throughout its lifetime.
More data needed
To better understand the evolutionary state of Sparkler and its clusters, the two scientists say more observations of similar types of clusters around other distant galaxies in the universe are needed.
This would help determine if Sparkler is a typical merger in the evolution of galaxies (similar to the Milky Way).
If not, then the details of the early evolution of galaxies, chemical enrichment, mass growth, and star cluster formation may need some revision.
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