The Leo Ring is an immense intergalactic cloud of hydrogen and helium gas some in diameter, in orbit of two galaxy, in the center of the Leo Group of galaxies, within the constellation of Leo.
Observation history
Radio astronomy 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 galaxy in a 19 February 2009
Nature paper.
In 2010, it was suggested that the gas was not primordial, but instead the result of a galactic collision between the two galaxies with which the ring is closely associated.
In 2021, analysis of several dense areas revealed several H II regions, powered by massive stars, a few which are O-type star.
Formation history
It has been suggested that 1.2 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 ring is now wide. The ring is composed of a collection of H I regions. A bridge of gas connects the ring to M96.[
]
