Lopsided Cosmic Explosion Reveals New Insights into Supernova Mystery

Scientists may have solved a supernova mystery. New observations of a recently exploded star are confirming supercomputer model predictions that the deaths of stellar giants are lopsided in which debris and the stars' cores hurtle off in opposite directions.

This latest study comes after the observation the remnant of supernova (SN) 1987A. The researchers detected a 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," said Fiona Harrison, one of the researchers, in a news release. "When it decays and turns into calcium, it emits gamma rays at a specific energy, which NuSTAR can detect."

The scientists analyzed the Doppler shifts of energy from titanium-44 and found that most of the material is moving away from NuSTAR. This is the best evidence yet that the mechanism that triggers Type II supernovae is inherently lopsided.

"If you make everything just spherical, the core doesn't explode," said Harrison. "It turns out you need asymmetries to make the star explode."

In fact, the asymmetrical nature of these supernovae could help solve one of the mysteries surrounding stellar deaths: why some supernovae collapse into neutron stars and others into a black hole. It could be that the high degree of asymmetry in some supernovae produces a dual effect; the star explodes in one direction while the remainder of the star continues to collapse in all other directions.

The findings reveal a bit more about these supernovae. This, in turn, may tell scientists a bit more about stellar evolution.

The findings are published in the journal Science.

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