Credit: Nasa
Leo Ring
Leo ring nebula is a immense intergalactic cloud of hydrogen and helium gas some 650 kilolight years (200 kpc) in diameter, in the centre of two galaxies, in the center of leo group galaxies, within the constellation Leo.
Observation Data
Distance : 38 ± 4.6 × 10^6 light years
Constellation : Leo
Physical Characteristics
Redius : 325 × 10^3 light years
Observation history of Leo Ring Nebula
Radio astronomers found the cloud in 1983. Scientists had theorized that the ring was primordial gas in the process of forming a galaxy. The GALEX satellite found ultraviolet emissions that astronomers at Johns Hopkins University and the Carnegie Institution for Science interpret to indicate star forming in newly formed dwarf galaxies 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 very nearly associated.
The search was on to find stars born within the Leo Ring.
The Leo Ring was widely thought to be a primordial cloud of gas, containing only the lightest materials — hydrogen, helium and a trace amount of lithium — that were made in the Big Bang, with no stars. Then in 2009, a team led by David Thilker of the John Hopkins University were studying the first ultraviolet (UV) observation of Messier 96, when they made a lucky discovery. On seeing that the Leo Ring was visible at the edge of their image, they were able to see clumps shining brightly in the UV that were possibly associated with the ring and could signal the appearance of massive stars. This challenged the then-held theory that the ring lacked stars. However, astronomers could still not say for sure whether stars were forming in the Leo Ring, or whether they were plucking up signatures of stars much further away in the background.
The search was on to discover stars born within the Leo Ring, young and massive enough to light up the heavy elements in the surrounding gas. These stars might be so faint and sparse that the hot areas around them might have escaped discovery for decades — detecting them would require a mighty instrument and telescope, such as the MUSE instrument on ESO’s VLT. Giovanni Cresci, who is also from INAF and was engaged in the research recently published in The Astrophysical Journal Letters, said, “We were already using MUSE and other elements at ESO to study nearby and faraway galaxies. So, when Edvige told us of the Leo Ring secret, we realised that MUSE would be ideal to finally provide an answer about the origin of this massive structure”.
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