OBSERVATIONS with the Hubble Space Telescope are adding weight to the idea
that gamma-ray bursters are fireballs expanding at nearly the speed of light in
distant galaxies. The bursts of gamma rays have puzzled astronomers for more
than two decades
(“God’s firecrackers”, Â鶹´«Ã½, 31 May, p 28).
Earlier this year, ground-based telescopes spotted a new optical source at
the place in the sky where a gamma-ray burster had appeared in February. Hubble
imaged the visible source on 26 March and again on 5 September, when the object
had faded to just two-thousandths of its earlier brightness.
At a meeting on gamma-ray bursters in Huntsville, Alabama, Andrew Fruchter of
the Space Telescope Science Institute in Baltimore said the pictures show the
burst was a dramatic explosion on the fringes of a galaxy billions of light
years away. “These observations are consistent with colliding neutron stars
creating the fireball,” he says.
