- 3781 - Peek-A-Boo Galaxy - one of the earliest found? Astronomers have discovered that a strange dwarf galaxy hidden for years in our cosmic neighborhood looks like it belongs in the early universe, despite having formed more recently.
--------------------- 3781 - Peek-A-Boo Galaxy - one of the earliest found?
- The tiny galaxy measuring just 1,200 light-years across earned the nickname 'Peekaboo' because it was hidden in the bright glare of a fast-moving foreground star and only emerged between 50 and 100 years ago.
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- The dwarf galaxy, HIPASS J1131–31, is located around 22 million light-years from Earth in the constellation of Hydra. Its strange appearance was confirmed using the Hubble Space Telescope after it showed up in observations from other space and ground-based telescopes.
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- The galaxy's ancient appearance comes from the fact that it has low abundances of elements that are heavier than hydrogen and helium, the universe's lightest and earliest-formed elements. Astronomers describe these heavier elements as 'metals' and are usually found in much more distant locations; thus, early galaxies that are typically described as 'extremely metal-poor.'
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- This galaxy represents the closest example of a galaxy formed by processes that existed predominantly throughout the universe shortly after the Big Bang. 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 that is inaccessible in the distant, early universe.
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- Tiny galaxy HIPASS J1131–31 peeks out from behind the glare of a Milky Way star positioned between Hubble and the galaxy.
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- During the earliest era of the universe, almost everything in the cosmos was composed of hydrogen and helium. These light elements were formed shortly after the Big Bang when the universe had expanded and cooled enough to allow electrons and protons to bond and form the first atoms and thus the first chemical elements.
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- These elements formed the first stars, which during their lifetimes 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 throughout the universe to become the building blocks of the next generation of stars.
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- As this process repeated throughout cosmic history, each subsequent generation of stars became more and more enriched with heavy elements and created the metal-rich universe that we see throughout our cosmic neighborhood today.
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- These heavier building blocks forged in earlier stars particularly carbon, oxygen, iron, and calcium would also become the foundational elements of life. Though early and distant galaxies were by default metal-poor, other examples of extremely metal-poor galaxies have previously been discovered closer to the Milky Way, our galaxy.
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- Peekaboo stands out from these galaxies because it seems to lack an older stellar population of ancient and thus metal-poor stars. Additionally, at just around 20 light-years from Earth, Peekaboo is much closer than other young metal-poor galaxies which are twice as distant.
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- Hubble was able to resolve around 60 stars in the dwarf galaxy which all appear to be no older than a few billion years. Astronomers then used “SALT” to discover Peekaboo's metal-poor nature, revealing it as one of the youngest and least-chemically-enriched galaxies ever detected in the local universe.
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- To improve the snapshot collected by the Hubble observations, astronomers will now use the James Webb Space Telescope to observe the galaxy alongside Hubble.
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- Due to Peekaboo's proximity to us, we can conduct detailed observations, opening up possibilities of seeing an environment resembling the early universe in unprecedented detail. Stay tuned, there is still more to learn.
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December 12, 2022 Peek-A-Boo Galaxy - one of the earliest found? 3781
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