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    Unusual Fossil Galaxy Discovered on Outskirts of Andromeda | This Could Reveal The History of the Universe?

    Gemini North telescope reveals a relic of the earliest galaxies.
    A unique ultrafaint dwarf galaxy has been discovered on the outer edge of the Andromeda galaxy, thanks to the astute eyes of an amateur astronomer examining archival data processed by NSF’s NOIRLabs Community Science and Data Center.

    The dwarf galaxy Pegasus V contained very few heavier elements and is likely a fossil of the first galaxies in follow-up observations by professional astronomers with the International Gemini Observatory, a program of NSF’s NOIRLab. An unusual ultrafaint dwarf galaxy has been discovered on the outskirts of the Andromeda galaxy with the help of multiple facilities at NSF’s NOIRLab.
    Faint stars in Pegasus V were discovered in subsequent deeper observations by astronomers using the larger 8.1-metre Gemini North telescope with the GMOS instrument, confirming that it is an ultrafaint dwarf galaxy on the outskirts of the Andromeda galaxy.
    Gemini North in Hawaii is half of the International Gemini Observatory. The observations with Gemini showed that the galaxy appears to be extremely poor in heavier elements compared to similar dwarf galaxies, meaning it is very old and likely a fossil of the first galaxies in the universe.
    “We have found an extremely faint galaxy whose stars formed very early in the history of the Universe,” commented Michelle Collins, an astronomer at the University of Surrey, UK, and lead author of the paper announcing the discovery. This discovery marks the first time such faint galaxy has been found around the Andromeda galaxy using an astronomical survey not specifically designed for the task.”
    The faintest galaxies are thought to be fossils of the very first galaxies to form, and these galactic relics hold clues to the formation of the earliest stars. While astronomers think the Universe is teeming with faint galaxies like Pegasus V,[2] they haven’t spotted nearly as many as their theories predict.

    If there really are fewer faint galaxies than predicted, it would pose a serious problem for astronomers’ understanding of cosmology and dark matter. Finding examples of these faint galaxies is therefore an important endeavor, but also a difficult one. Part of the challenge is that these faint galaxies are extremely difficult to spot, appearing as just a few stars hidden in huge images of the sky.
    The problem with these extremely faint galaxies is that they have very few of the bright stars we typically use to identify them and measure their distances, explained Emily Charles, a PhD student at the University of Surrey who is also at the study was involved. Gemini’s 8.1-meter mirror allowed us to find faint, old stars, allowing us to both measure the distance to Pegasus V and determine that its stellar population is extremely old.
    The heavy concentration of old stars the team found in Pegasus V suggests that the object is likely a fossil of the first galaxies. Compared to the other faint galaxies around Andromeda, Pegasus V appears to be uniquely old and metal-poor, suggesting that its star formation did indeed stop very early. “We hope that further study of the chemistry of Pegasus V will provide clues to the earliest periods of star formation in the Universe,” Collins concluded. This small fossil galaxy from the early Universe may help us understand how galaxies form and whether our understanding of dark matter is correct – The National Science Foundation. In this case, Gemini assisted this international team to confirm the presence of the dwarf galaxy, physically associate it with the Andromeda Galaxy, and determine the metal deficiency of its evolved stellar population.
    Upcoming astronomical facilities should shed more light on faint galaxies. Pegasus V witnessed a period in the history of the Universe known as reionization, and other objects from that period will soon be observed with NASA’s James Webb Space Telescope. Astronomers also hope to discover more such faint galaxies in the future with the Vera C. Rubin Observatory, a program of NSF’s NOIRLab. The Rubin Observatory will conduct an unprecedented, decades-long survey of the optical sky called the Legacy Survey of Space and Time (LSST).
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