Watch the off-kilter explosion of a supergiant star

Supercomputer model predictions say that the deaths of stellar giants are lopsided affairs in which debris and the stars’ cores hurtle off in opposite directions. New observations of a recently exploded star back this up.

While observing the remnant of supernova (SN) 1987A, NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, recently detected the unique energy signature of titanium-44, a radioactive version of titanium that is produced during the early stages of a particular type of star explosion, called a Type II, or core-collapse supernova.

“Titanium-44 is unstable. When it decays and turns into calcium, it emits gamma rays at a specific energy, which NuSTAR can detect,” says Fiona Harrison, the professor of physics at Caltech, and NuSTAR’s principal investigator.

By analyzing direction-dependent frequency changes—or Doppler shifts—of energy from titanium-44, Harrison and her team discovered that most of the material is moving away from NuSTAR. The finding, which appears in Science, is the best proof yet that the mechanism that triggers Type II supernovae is inherently lopsided.