Stars Of The Leo Ring

摘要

A massive ring of neutral hydrogen (Hi) was detected during radio observations in the 1980s, orbiting the Ml05 and NGC 3384 galaxies in the constellation Leo. Called the Leo ring, it remains a mysterious structure, thought to be a remnant primordial cloud left over from when the Leo I group galaxies formed. Until now the Leo ring has been detected only in the radio region of the spectrum (Hi emission), suggesting an absence of stars. Now observations from the GALEX (Galaxy Evolution Explorer) orbiting space telescope have detected ultraviolet light originating from parts of the ring, indicating recent massive star formation in substructures. If such structures were common in the early Universe, they may have produced a large, as yet undetected population of faint, metal-poor, halo-lacking dwarf galaxies.