Detected using infrared light, it represents a new type of stellar explosion produced from the merger of two compact objects, most likely neutron stars, NASA reported Monday.
Kilonovas are about 1,000 times brighter than a nova, which is caused by the eruption of a white dwarf, but are 1/10th to 1/100th the brightness of a typical supernova, the self-detonation of a massive star.
After a Gamma-ray burst came into view of the Swift space telescope June 3, the Hubble Space Telescope looked at the same area nine days later to see if there were any remnants and spotted a faint red object.
Astrophysicists have predicted short-duration Gamma-ray bursts would be created when a pair of super-dense neutron stars in a binary system spiral together, and the Hubble observations have proved the long-suspected connection between Gamma-ray bursts and kilonovas, astronomers said.
"This observation finally solves the mystery of the origin of short gamma ray bursts," study lead author Nial Tanvir of the University of Leicester in Britain said.
"Many astronomers, including our group, have already provided a great deal of evidence that long-duration gamma ray bursts (those lasting more than two seconds) are produced by the collapse of extremely massive stars," he said.
"But we only had weak circumstantial evidence that short bursts were produced by the merger of compact objects. This result now appears to provide definitive proof supporting that scenario."