Supernova Discovery Reveals How the Biggest, Brightest Stars Die

The most massive and luminous stars were long suspected to explode when they die, and astronomers now have the most direct evidence yet that these cosmic behemoths go out with a bang.

These findings shed light on the star explosions that provide the universe with the ingredients for planets and life, the researchers added.

With a mass more than 330,000 times that of Earth, the sun accounts for 99.86 percent of the solar system's total mass. But as stars go, the sun is a lightweight. The largest and most luminous stars in the universe are Wolf-Rayet stars, which are more than 20 times as massive as the sun and at least five times as hot. Only a few hundred of these titan stars are known to astronomers. [Biggest Star Mysteries of All Time]

The intense heat of Wolf-Rayet stars forces their matter apart, making them extraordinarily windy stars. They usually lose the mass equivalent to that of the Earth each year, blowing winds at up to 5.6 million mph (9 million km/h).




How giant stars die

Astronomers long suspected that Wolf-Rayet stars violently self-destructed as supernovas, the most powerful stellar explosions in the universe. These outbursts are bright enough to momentarily outshine their entire galaxies, and enrich galaxies with heavy elements that eventually become the building blocks for planets and life.

However, the gigantic amounts of matter these stars blow out usually obscure them completely, so scientists weren't sure how they form, live and die.

"Finding what kind of star exploded, after it already exploded, is, of course, a hard problem, since the explosion destroys much of the information," said study author Avishay Gal-Yam, an astrophysicist at the Weizmann Institute of Science in Israel.

Some researchers even raised doubts as to whether Wolf-Rayet stars detonated as supernovas at all. "Some modelers predict that massive Wolf-Rayet stars will collapse into a black hole 'quietly,' without making a luminous supernova," Gal-Yam told Space.com.

Now, for the first time, scientists have direct confirmation that a Wolf-Rayet star died in a supernova. They detail their findings in the May 22 issue of the journal Nature.

The researchers focused on a supernova named SN 2013cu, which exploded about 360 million light-years away from Earth in the Bootes constellation. This explosion was a Type IIb supernova, meaning it took place after the core of its star ran out of fuel, collapsing into an extraordinarily dense nugget in a fraction of a second and rebounding with a blast outward. What is left over after such supernovas is either a neutron star or a black hole.

http://www.space.com/25961-supernova-death-biggest-brightest-stars.html