Observations of the tiny Sparkler dwarf galaxy have revealed that it is embedded in a system of ancient star clusters and is hungrily feeding on its smaller galactic companions to grow.
This means that Galaxywhich was discovered in the first data from the James Webb Space Telescope (JWST), resembles early cannibalism Milky Way which also grew by feeding on smaller galaxies. Thus, the investigation of this galaxy provides astronomers with a unique view of how the Milky Way evolved.
The Sparklerlocated in the southern constellation Volens, it got its name because it is surrounded by about two dozen bright globular clusters, compact clusters of ancient stars. Each of these clusters can contain about a million stars. Our galaxy currently hosts around 200 globular clusters of its own.
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The team, led by Swinburne University professor Duncan Forbes and San Jose State University professor Aaron Romanowsky, examined the age of Sparkler and its surroundings by looking at the abundance of elements heavier than hydrogen and helium. Astronomers call these heavy elements “metals”.
Looking at the compact star clusters around the galaxy, they noticed that they look like younger versions of the clusters around the Milky Way. Many are rich in metals, similar to the globular clusters in the central bulge of our galaxy. The researchers also observed metal-poor middle-aged clusters that are associated with a satellite galaxy that Sparkler is devouring, with its globular clusters acting like a desert.
The Sparkler Galaxy is currently only 3% as massive as our galaxy, but researchers expect it to grow through this feeding process on cosmic timescales to eventually equal the mass of the Milky Way as we see it today.
“We appear to be witnessing first-hand the assembly of this galaxy as it increases in mass – in the form of a dwarf galaxy and multiple globular clusters,” said Forbes. in a statement (opens in new tab). “We are excited about this unique opportunity to study both the formation of globular clusters and an infant Milky Way, at a time when the Universe was only 1/3 of its current age.”
Looking back in time with a little help from Einstein
The Sparkler Galaxy is located 9 billion light-years of Earth, which means that astronomers are seeing what it was like about 4 billion years after the big Bang. The observations are possible due to the JWST’s impressive infrared observation power and a phenomenon first predicted by Albert Einstein in 1915.
the great physicist theory of general relativity suggests that objects with great mass “warp” the fabric of space like a heavy ball placed on a stretched rubber sheet. As with this simple analogy, the larger the mass, the more extreme the curve it causes.
This means extremely massive objects like black holes or galaxies can “squash” space enough to distort light as it passes through them. As a result, if light from a background object passes through this distortion, its travel time will be affected. This can cause the background object to be amplified by this foreground landing object, which is described as a “gravitational lensing”.
The Sparkler galaxy is illuminated by gravitational lensing that allows the JWST to localize its light that has traveled 9 billion years to reach the powerful space telescope.
The team will continue to study globular clusters around Sparkler to learn more about this distant early galaxy and, in turn, our own galaxy, the Milky Way, and its evolution.
“The origin of globular clusters has been a longstanding mystery, and we’re excited that JWST can look back in time to see them in their youth,” said Romanowsky.
The team’s research is published in the journal Monthly Notices of the Royal Astronomical Society (opens in new tab)
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