article_snippet.sent: Astronomers say the unique event happened in an ancient cluster of stars at the edge of the Milky Way galaxythe Milky Way galaxy.
article_snippet.sent: Overlapping X-ray sources and stars near the center of the cluster the cluster also causes the image to appear white.
article_snippet.sent: For example, the source does not show some of the distinctive features of a binary containing a neutron star, such as pulsations or rapid X-ray bursts.
article_snippet.sent: Also, the source is much too faint in radio waves to be part of a binary system with a stellar-mass black hole.
highlights_snippet.sent: Occurred in ancient cluster of stars at the edge of the Milky Way galaxy .
  