A galaxy that goes the distance?
To find the galaxy, Daniel Schaerer of the Geneva Observatory in Sauverny, Switzerland, and his colleagues examined the central region of a relatively nearby cluster of galaxies, Abell 1835. The cluster's enormous mass acts as a gravitational lens, magnifying, brightening, and distorting images of more-distant galaxies. The astronomers used an infrared detector on the European Southern Observatory's Very Large Tele scope in Paranal, Chile.
Comparing images of the same region taken with two other telescopes, the researchers verified that the newly identified galaxy, dubbed Abel11835IR1916, shows up in near-infrared images but not in visible light--an indication that the galaxy is extremely distant. Infrared-spectra reveal a specific wavelength that appears to represent the ultraviolet glow of hydrogen atoms, the researchers report in an upcoming Astronomy & Astrophysics. The team posits that the gas' ultraviolet radiation has been shifted to a longer, near-infrared wavelength by the galaxy's great distance.
Other astronomers have their doubts. Richard G. McMahon of the University of Cambridge in England says that hydrogen may not be the origin of the near-infrared wavelength observed by the team. That could undermine the argument for the galaxy residing so far from Earth.
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|Date:||Apr 24, 2004|
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