ASCA identified several neutron stars, such as RCW 103 and Kes 73. Another big hit for ASCA was the discovery of cosmic rays shooting away from supernova 1006. Cosmic rays are atomic particles that whip through space at nearly light speed. Many astronomers suspected that these particles are accelerated to such speeds by star explosions, such as SN 1006, which Chinese astronomers actually recorded in the year 1006. ASCA provided the first observational evidence of cosmic ray acceleration.
Stars go out with a bang, with explosions that glow in X rays.
ASCA was even sensitive enough to study stellar coronae , the thin, hot atmosphere surrounding most stars, including our own. Astronomers studied the abundances of elements such as iron, silicon and sulfur in unprecedented detail. Before ASCA, only the sun's corona could be studies so thoroughly. On the largest and most distant scale, ASCA studied clusters of galaxies. We know this from measuring the abundance of elements in distant clusters, which could only have been produced from massive stars.