June 19, 2001 Astronomers have for the first time taken infrared pictures of individual stars in a galaxy called NGC 3379, about 30 million light years from Earth.
The pictures were taken by Michael Gregg of the University of California, Davis, and the Lawrence Livermore National Laboratory, in collaboration with colleagues from the Space Telescope Science Institute, the Universidad Catolica de Chile, and the University of Hertfordshire, England. The researchers used the Near Infrared Camera and Multiobject Spectrograph (NICMOS) on the Hubble Space Telescope to take the pictures.
This represents the first time that individual stars have been resolved in the infrared at this distance, said Gregg.
Infrared images allow astronomers to study what stars are made of. This can tell astronomers how stars are formed in this galaxy, allowing a comparison with our own Milky Way and other nearby galaxies.
The high-resolution images also show that NGC 3379 contains variable stars, which change in brightness over time. Some stars clearly seen on one date image were no longer visible three months later.
Elliptical galaxies were previously thought to contain few variable stars. If NGC 3379 is typical, current assumptions about elliptical galaxy evolution may need to be revised, Gregg said.
NGC 3379, also known as M105, is visible through a small telescope. It appears as a fuzzy patch in the constellation Leo and is high in the sky just after dark in June.
The results were presented at the American Astronomical Society meeting in Pasadena, Calif., earlier this month.
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