Right ascension 10 48 19.0 Constellation Leo | Declination +12° 41′ 21″ | |
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Distance 38±4.6×10 ly (11.8±1.4×10 pc) Radius 325×10 ly (100×10 pc) | ||
The Leo Ring is an immense intergalactic cloud of hydrogen and helium gas some 650 kilolight-years (200 kpc) in diameter, in orbit of two galaxies, in the center of the Leo Group of galaxies, within the constellation of Leo.
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Observation history
Radio astronomers discovered the cloud in 1983. Astronomers had theorized that the ring was primordial gas in the process of forming a galaxy. The GALEX satellite detected ultraviolet emissions that astronomers at Johns Hopkins University and the Carnegie Institution for Science interpret to indicate star creation in newly forming dwarf galaxies in a 19 February 2009 Nature paper. In 2010, it was found that the gas was not primordial, but the result of a galactic collision between the two galaxies the ring is closely associated with.
Formation history
A billion years ago, NGC 3384 collided with M96, at the heart of the Leo Group, expelling a galaxy's worth of gas into intergalactic space. This gas gathered into a vast set of clouds, the Leo Ring.
The two galaxies have now drifted to being 38 Mly (12 Mpc) apart, and the ring is now 650 kilolight-years (200 kpc) wide. The ring is composed of a collection of H I regions. A bridge of gas connects the ring to M96.