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The Star from the Approximate Beginning of Time

Astrophysicists are wise beyond their years. In fact they're wise beyond almost all years, ever, because they've measured the age of the universe. And found a star that's been here almost as long.

NASA
"Damn young stars, you whipper-stellars with your metal and your baggy disk orbits! Get off my globular cluster!"

HD 140283 is 14.5 plus or minus 0.8 gigayears old, compared to the universe's 13.80 plus or minus 0.04 gigayears, and some idiots are already in the comments complaining about that being impossible. It's ironic that many of humanity's worst errors don't understand how to read errors. The star was measured by the Hubble space telescope, a system designed to constantly remind us that the universe is unbelievably awesome.

NASA, ESA, W. Clarkson (Indiana University and UCLA), and K. Sahu (STScI)
And very much a fan of sequins.

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Gravity Wave Radiation

Stars are supported against gravity by the thermonuclear fusion in their cores. Fusing lighter atoms into heavier ones releases energy, but those heavier elements require higher temperatures to fuse again. If the star isn't massive enough to ignite the next element, or if it reaches iron (which, Robert Downey Jr.'s characterization notwithstanding, is stable and can't sustain a star), fusion stops. Then gravity gets to continue the job it started billions of years before: crushing the absolute hell out of everything ever.

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The Largest Star

Stars are born by pulling in as much material as they can, but above a certain size shine so brightly that it blows away any new material. This creates an upper limit on the size of stars around 150 solar masses. Which is why it was surprising to find one with 260 shining in the Arches cluster.

ESO
Very not small, but very far away.

The last time there was anything this ludicrously powerful and unstable in the heavens, he was called Zeus. Scientists were delighted to find R136a1, because in science something that proves you wrong is the most precious thing in existence. It's how you learn new things (and write the first paper about them). Astrophysicists think some stars skipped over the stellar mass limit by ganging up on it, creating something twice the size of everything ever seen before by cannibalistic cosmic collisions. The resulting stellar Constructicon is 10 million times more luminous than the sun.

The resulting star will explode in hypernova. That's what scientists say when "supernova," the brightest and most violent event regular matter can conceive of, simply doesn't do the process justice. The star is so massive that its collapse could break the load limit on space-time itself, ripping a hole in our understanding of reality as it collapses into a black hole, a gravitational singularity excising itself from the observable universe, an ultimate everything-compactor from which not even light can escape.

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Pair Instability Supernova

Pair instability supernova. The only reason that's not a punk romance anthem is that not enough singers know how awesome existence truly is (although Kim Boekbinder does well with the hottest music video ever made). Stars explode when they run out of core fuel, but if they're truly ludicrously gigantic, they can go into meltdown long before using up all their ability. Just like Hollywood stars.

Digital Vision./Digital Vision/Getty
"Do you want me to undergo total gravitational collapse and trash your lights? Then why are you trashing my scene?"

If a star is literally burning with the hatred of over a hundred suns, energy density in the core can get high enough to start spontaneously generating antimatter. Energy so intense, it starts congealing into mass as pairs of electrons and positrons.

The one thing everyone knows about antimatter is that it explodes when it touches matter. Very few places in the universe have more matter than a star's core. And all of those are created from a star's core. But this superstar's core is so ludicrously energetic that mere antimatter annihilation wouldn't even dent it. All that would do is release the energy again. The problem is the instant of delay as it back-and-forths across E=MC2. For that infinitesimal sliver of time, the energy wasn't countering gravity.

And now the star is doomed.

Ryan McVay/Photodisc/Getty Images
No, gravity will not "let things go for a minute." That is the opposite of what gravity does.

Scores of suns suddenly clench down, spiking the pressure and temperature, setting off total fusion in the core. Most stars burn as reactors. This one goes off as a bomb. Something several dozen times more massive than the solar system suddenly detonates with a blast that would make Vishnu duck and cover.

The star is utterly destroyed. The blast leaves no core, no neutron star, nothing. An entire star is blasted into interstellar dust. And we've seen it happen.

SN2007bi was discovered by the Nearby Supernova Factory (and that's the "good band name" game officially won and ended forever). It was so violent that the blast alone fused over three suns' worth of material into radioactive nickel, 6 thousand million billion billion tons of new radioisotope, which then irradiated the wreckage to make it glow for months. That's an explosion so badass, it created more nuclear material AFTER it went off, just to make the remains glow in the dark longer.

Luke writes more on his website, tumbles, and replies to every single tweet.

We can't let silly little things like thermonuclear explosions vaster than the planet steal all the glory, so we sent up astronauts to do the 5 Most Badass Things Ever Done in Space. Though they pale against star corpses in 6 Mind-Blowing Things Nobody Taught You About Black Holes. Or unleash your spacemagination with Pink Alert, and Other Emergencies on the Starship Enterprise.