Produced by: Mohsin Shaikh
An ultra-diffuse galaxy, FCC 224, was observed with the Hubble Space Telescope, revealing a structure both expansive and elusive, defying traditional galaxy classifications.
Nestled in the Fornax Cluster, FCC 224 has existed in cosmic stillness for 10 billion years, its quiescence a stark contrast to the chaos of galactic formation and mergers.
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Astronomers found FCC 224’s 12 globular clusters to be unusually luminous, with some reaching an absolute magnitude of -9.0, an enigmatic anomaly for a galaxy of this scale.
Representative pic/NASA
With its globular clusters amounting to 2% of its total stellar mass, FCC 224 houses an overmassive GC system, challenging conventional theories of galaxy evolution.
Representative pic/NASA
Spectroscopic analysis from the Keck Cosmic Web Imager revealed the galaxy's age of 10.1 billion years and a metallicity level of -1.25 dex, offering insights into its ancient past.
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Unlike their sprawling counterparts in other galaxies, FCC 224’s globular clusters are compact, with half-light radii between 7.8 and 15.6 light years, hinting at a unique evolutionary path.
Representative pic/NASA
A pattern of radial mass segregation was discovered, with the brightest and most massive globular clusters concentrated toward the center, suggesting a gravitational sorting over cosmic time.
Representative pic/NASA
The galaxy exhibits no significant color gradient, and its globular clusters share a nearly identical hue to the surrounding starlight, implying a singular burst of intense star formation.
Representative pic/NASA
Yimeng Tang and colleagues at UCSC conclude that FCC 224’s globular cluster system is a cosmic outlier, demanding deeper theoretical work to unravel the origins of its peculiar properties.