'Hubble caught it again': A galaxy that should not exist yet shines too bright
Produced by: Mohsin Shaikh
Faint Giant
An ultra-diffuse galaxy, FCC 224, was observed with the Hubble Space Telescope, revealing a structure both expansive and elusive, defying traditional galaxy classifications.
Silent Sentinel
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.
Representative pic
Glowing Clusters
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
Heavy Heritage
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
Aged Light
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.
Representative pic/NASA
Tight Formation
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
Inner Giants
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
Color Locked
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
Final Riddle
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.