This superluminous supernova just blindsided science

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Jul 29, 2017

Supernovae are already blinding, but just imagine an immense explosion of a dying star that blazes with over triple the brightness of the hundred billion stars in our galaxy.

Superluminous supernovae (which totally sounds like the newest astro-comic) are the brilliant death throes of a massive collapsing star, except anywhere from 10 to 100 times brighter than the average supernova. Unsolved mysteries lurk behind all this light. What kind of star would explode with such extreme luminosity? What kind of processes does it take to fuel this phenomenon?

Astronomers Yen-Chen Pan and Ryan Foley zeroed in on one anomaly even among the superluminous leviathans, DES15E2mlf, first discovered by the Dark Energy Survey (DES). It is thought to have flared 10 billion years ago in an alien galaxy during a period known as “cosmic high noon,” during which there was the highest rate of star formation in the universe. What makes this anomaly even more anomalous is where it exploded.

Stars with fewer metals—which in astronomy are any elements heavier than helium—retain more mass when they die. More mass means monster explosions. This explains why most superluminous supernovae are found bursting into flame in low-mass or dwarf galaxies which tend to have low levels of metallicity. DES15E2mlf seems to defy science because it exists in a higher-mass galaxy where the occurrence of supernovae with this insane level of intensity was once thought impossible.

DES15E2mlf looks like little more than a speck of glitter in this Dark Energy Camera (DECam) image, but is actually thrice as bright as all the stars in the Milky Way. 

We know metallicity affects the life of a star and how it dies, so finding this superluminous supernova in a higher-mass galaxy goes counter to current thinking,” Foley said. “But we are looking so far back in time, this galaxy would have had less time to create metals, so it may be that at these earlier times in the universe’s history, even high-mass galaxies had low enough metal content to create these extraordinary stellar explosions.”

Foley and Pan’s observations, recently published in Monthly Notices of the Royal Astronomical Society, may illuminate things we never knew about the birth of stars and galaxies. Superluminous supernovae boost the interstellar gas in evolving galaxies with metallic elements. It is still unknown how many exist relative to normal supernovae, because dimmer normal supernovae are difficult to observe at distances that span billions of light-years. It is possible that blindingly bright stellar outbursts like DES15E2mlf could be telling us something significant about the time period during which they occurred. We just don’t know what.

It’s important simply to know that very massive stars were exploding at that time,” said Foley, who believes that if we could time-warp billions of years back, we might have even seen such spectacular light shows in the Milky Way.

(via Astronomy Now)