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.

Leo Ring
Interstellar cloud
Intergalactic cloud
H I region
Chart of the Leo ring in a GALEX image surrounding M105 and NGC 3384
Observation data: J2000.0[1][2] epoch
Right ascension10h 48m 19.0s [2]
Declination+12° 41′ 21″ [2]
Distance38±4.6×106 [2] ly   (11.8±1.4×106 [2] pc)
ConstellationLeo
Physical characteristics
Radius325×103 [3] ly   (100×103 [4] pc)
See also: Lists of nebulae

Observation history

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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.[5] 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.[3]

In 2021, analysis of several dense areas revealed several H II regions, powered by massive stars, a few which are O-type stars.[6]

Formation history

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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.[3][4]

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.[3][4]

References

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  1. ^ "NAME Leo Ring". SIMBAD. Centre de données astronomiques de Strasbourg.
  2. ^ a b c d e "Leo Ring". NASA/IPAC Intergalactic Database. Archived from the original on 2022-04-23. Retrieved 2015-11-08.
  3. ^ a b c d Léo Michel-Dansa; Pierre-Alain Duc (2010). "The mysterious Leo giant gas ring explained by a billion year old collision between two galaxies". Canada France Hawaii Telescope. Archived from the original on 2013-10-10. Retrieved 2015-11-08.
  4. ^ a b c Michel-Dansac, Leo; Duc, Pierre-Alain; Bournaud, Frederic; Cuillandre, Jean-Charles; Emsellem, Eric; Oosterloo, Tom; Morganti, Raffaella; Serra, Paolo; Ibata, Rodrigo (2010). "A collisional origin for the Leo ring". The Astrophysical Journal Letters. 717 (2) (published July 2010): L143–L148. arXiv:1005.4208. Bibcode:2010ApJ...717L.143M. doi:10.1088/2041-8205/717/2/L143. S2CID 54012759.
  5. ^ "New stars from old gas surprise astronomers". PhysOrg.com. 18 February 2009. Archived from the original on 26 September 2011. Retrieved 18 February 2009.
  6. ^ Corbelli, Edvige; Mannucci, Filippo; Thilker, David; Cresci, Giovanni; Venturi, Giacomo (2021-07-01). "Gaseous nebulae and massive stars in the giant H I ring in Leo". Astronomy and Astrophysics. 651: A77. arXiv:2104.07133. doi:10.1051/0004-6361/202140398. ISSN 0004-6361.