An X-ray picture (false color) taken with the European Space Agency's XMM-Newton
telescope overlayed on an optical image of the NGC 4325 group of galaxies
reveals a huge cloud of hot gas surrounding the group. The gas cloud is
1.9 million light-years in diameter and has a temperature of about 10 million
degrees Kelvin (about 18 million Fahrenheit). The existence of this gas
cloud implies that about 90% of the mass in this group is in the form of
dark matter. The optical image of the field was taken with the 1-meter (40-inch)
Swope Telescope at Las Campanas Observatory, in Chile. This photograph was
presented to the American Astronomical Society meeting in Albuquerque, New
Mexico on June 4, 2002.
PHOTO CREDIT: Dr. John S. Mulchaey, The Carnegie Observatories. |
