Observation of X-ray Lines from a Gamma-Ray Burst (GRB991216): Evidence of Moving Ejecta from the Progenitor
We report on the discovery of two emission features observed in the x-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 December 1999 by the Chandra X-ray Observatory. These features are identified with the Lyα line and the narrow recombination continuum by hydrogenic ions of iron at a redshift z = 1.00 +/- 0.02, providing an unambiguous measurement of the distance of a GRB. Line width and intensity imply that the progenitor of the GRB was a massive star system that ejected, before the GRB event, a quantity of iron ~0.01 of the mass of the sun at a velocity ~0.1 of the speed of light, probably by a supernova explosion.
- Pub Date:
- November 2000
- 11 pages,2 fig.s, link to the published paper in Science, 290, 955 (2000) through http://www.ias.rm.cnr.it/grb/gb991216.html