How white-dwarf stars merge and become a supernova

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Washington, January 8 (ANI): A team of astrophysicists from the Max-Planck-Institute for Astrophysics in Garching, Germany, has used computer simulations to show that some supernovae are a result of the merger of two white dwarfs, compact remnants of extinguished stars.

As supernovae are used by astronomers to measure cosmic distances and study the expansion history of our Universe, understanding their mechanism is one of the key challenges in astrophysics.

Intermediate-mass stars such as our Sun end their lives as white dwarfs consisting of carbon and oxygen.

In a binary system, two exotic white dwarfs can form.

As they orbit each other, they are emitting gravitational waves. The resulting energy loss shrinks the orbit, the stars approach each other and ultimately they merge.

It has long been speculated that these events may produce Type Ia supernova explosions.

The supernova research group at the Max Planck Institute for Astrophysics has now performed computer simulations of two merging white dwarfs in unprecedented detail.

In the case of equal masses of the two white dwarfs, the merger is particularly violent.

Part of the material of one white dwarf crashes into the other and heats up the carbon/oxygen material such that a thermonuclear explosion triggers.

This disrupts the stars in a supernova explosion.

"With our detailed explosion simulations, we could predict observables that indeed closely match actual observations of Type Ia supernovae," explained Friedrich Ropke of the supernova team.

Therefore, it has been demonstrated that white dwarf mergers contribute to Type Ia supernovae, although this scenario probably cannot account for all these explosions.

"Supernovae are among the brightest observed cosmic explosions," explained Wolfgang Hillebrandt, director at the Max Planck Institute for Astrophysics.

"How they form, however, remains largely unknown. With our simulations we have now shed light on at least part of the old riddle of the progenitors of Type Ia supernovae," he added. (ANI)

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