Unravelling the Mysteries of the Leo Ring: An Absorption Line Study of an Unusual Gas Cloud

Abstract

Since the 1980's discovery of the large (2x10^9 Msun) intergalactic cloud known as the Leo Ring, this object has been the center of a lively debate about its origin. Determining the origin of this object is still important as we develop a deeper understanding of the accretion and feedback processes that shape galaxy evolution. We present HST/COS observations of three sightlines near the Ring, two of which penetrate the high column density neutral hydrogen gas visible in 21 cm observations of the object. These observations provide the first direct measurement of the metallicity of the gas in the Ring, an important clue to its origins. Our best estimate of the metallicity of the ring is ~10% Zsun, higher than expected for primordial gas but lower than expected from an interaction. We discuss possible modifications to the interaction and primordial gas scenarios that would be consistent with this metallicity measurement.

arXiv comment11 pages, 7 figures, accepted ApJ

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Cited by in corpus (5)

• The Structure of the Circumgalactic Medium of Galaxies: Cool Accretion Inflow Around NGC 1097
• Heavy elements unveil the non primordial origin of the giant HI ring in Leo
• The detection of a massive chain of dark HI clouds in the GAMA G23 Field
• The Arecibo Galaxy Environment Survey XII : Optically dark HI clouds in the Leo I Group
• Gaseous nebulae and massive stars in the giant HI ring in Leo