peekaboo! Strange tiny galaxy offers insight into the early history of the universe
Astronomers have discovered that a strange dwarf galaxy hidden for years in our cosmic neighborhood appears to belong to the early universe, despite having formed more recently.
the little one galaxy measuring just 1,200 light-years across it earned the nickname “Peekaboo” because it was hidden in the glow of a fast-moving foreground. star and it only emerged between 50 and 100 years ago.
The dwarf galaxy, officially named HIPASS J1131–31, is located about 22 million light-years from Earth in the constellation Hydra. His strange appearance was confirmed with the Hubble Space Telescope after it appeared in observations from other space and ground telescopes.
Related: The James Webb Space Telescope looks at the lonely dwarf galaxy with brilliant results
The galaxy’s falsely ancient appearance comes from the fact that it has a low abundance of elements that are heavier than hydrogen and helium, the lightest and oldest-formed elements in the universe. Astronomers describe these heavier elements as “metals” and are usually found in much more distant places; hence, early galaxies that are usually described as “extremely metal-poor”.
As such, HIPASS J1131–31 represents the closest example of a galaxy formed by processes that existed predominantly throughout the universe shortly after the Big Bang.
“Discovering the Peekaboo Galaxy is like discovering a direct window into the past, allowing us to study its extreme environment and stars at a level of detail inaccessible in the distant, early universe,” study co-author and astronomer at the ‘Space Telescope Science Institute. , Gagandeep Anand said in a statement (opens in a new tab).
During the earliest era of the universe, almost everything in the cosmos it was composed of hydrogen and helium (opens in a new tab). These light elements were formed shortly after the big bang when the universe had expanded and cooled enough to allow electrons and protons to join together to form the first atoms and thus the first chemical elements.
These elements formed the first stars, which during their lifetime forged heavier elements. When this first generation of extremely metal-poor stars reached the end of their lives and exploded, they spread these heavy elements around the world. universe to become the building blocks of the next generation of stars.
As this process repeated itself throughout cosmic history, each subsequent generation of stars became increasingly enriched in heavy elements and created the metal-rich universe we see in our cosmic neighborhood today.
These heavier building blocks forged in earlier stars, especially carbon, oxygen, iron and calcium, would also become the building blocks of life.
Although early and distant galaxies were by default metal-poor, other examples of extremely metal-poor galaxies closer to the Milky Wayour galaxy
Peekaboo stands out from these galaxies because it does not appear to have an older stellar population of old and therefore metal-poor stars. Also, at only about 20 light-years from Earth, Peekaboo is much closer than other metal-poor young galaxies that are twice as far away.
First discovered two decades ago by research co-author Professor Bärbel Koribalski in data collected in the HI Parkes All Sky survey, the dwarf galaxy HIPASS J1131–31 did not immediately present itself as anything special to astronomers. He took observations in far ultraviolet light from the now defunct NASA space base Galaxy Evolution Explorer (GALEX) to reveal the nature of Peekaboo as a strange compact blue dwarf galaxy.
“At first we didn’t realize how special this little galaxy is,” Koribalski said. “Now with combined data from the Hubble Space Telescope, the Great Telescope of Southern Africa (SALT) and others, we know that the Peekaboo Galaxy is one of the most metal-poor galaxies ever detected.”
Hubble was able to resolve about 60 stars in the dwarf galaxy that appear to be no more than a few billion years old. Astronomers used SAL to uncover the metal-poor nature of Peekaboo, revealing it to be one of the youngest and least chemically enriched galaxies ever detected in the local universe.
Since the local universe has had more than 13 billion years to evolve, Peekaboo’s metal-poor nature marks it as extremely unusual, and astronomers still have much to learn about this dwarf galaxy.
To enhance the snapshot of HIPASS J1131–31 taken by the Hubble observations, which were part of the Survey of Every Known Nearby Galaxy, astronomers will now use the James Webb Space Telescope to observe the galaxy alongside the Hubble.
Hopefully, this will reveal more about their population of stars and how metal-enriched they are.
“Because of Peekaboo’s proximity to us, we can make detailed observations, opening up possibilities to see an environment similar to the early universe in unprecedented detail,” concluded Anand.
The team’s research has been accepted for publication in the Monthly Notices of the Royal Astronomical Society.
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