Strange star survived a supernova explosion only to shine even brighter than before

(ORDO NEWS) — When it comes to style, nothing beats the end of a white dwarf. Their thermonuclear self-destruction is among the most powerful explosions in space, causing a star to disappear in a blaze of glory.

At least that’s the idea. The discovery confirms that some white dwarfs fake their deaths with dim performance, only to continue to shine even brighter than before.

Ten years ago, the supernova SN 2012Z was seen in the nearby spiral galaxy NGC 1309 and briefly glowed. in a swan song, which, by all accounts, should herald her destruction.

Images of her home galaxy were taken many years ago, so figuring out which star exploded simply required examining subsequent images to determine the now empty spaces.

“We expected to see one of two things when we received the latest Hubble data. Either the star would have completely disappeared, or perhaps it would still be there, which means “The star we saw in the images before the explosion exploded the wrong one,” says UC Santa Barbara astronomer Curtis McCully.

“No one expected to see a surviving star that would be brighter. real puzzle.”

As unexpected as it was, the sighting was not unprecedented, which has contributed to growing evidence that life after death may not be such a strange thing for white dwarfs.

As soon as a star with the mass of our Sun compresses the last remnants of helium into carbon and oxygen, it collapses into a dense, white-hot sphere the size of our Earth. Without the mass needed to create larger elements, it simmers, cooling down over eons until it eventually turns into a cold black lump.

If such a depleted stellar core has a generous companion star orbiting nearby, life could be wiped out. slightly longer as it pumps out some extra gas.

However, at a critical point, all this extra mass risks pushing carbon into fusion, causing an uncontrolled reaction that releases massive amounts of energy in a flash that rips the star apart in what is known as a Type Ia supernova.

Normally, nothing of note remains in the space once occupied by a white dwarf—just an expanding cloud of stellar guts drifting into space, faintly glowing with residual radiation.

These specific explosions are so clockwork that they all burn at approximately the same brightness, making them convenient for measuring distances in the universe.

But not all explosions are so standard. The more common Type Iax supernovae look less like fireworks and more like wet squibs, exploding slowly in a comparatively muffled whimper.

They may not even be that destructive, with evidence of high-density matter with evidence of a thick photosphere found after several less spectacular supernovae.

Strange star survived a supernova explosion only to shine even brighter than before 2
Color images of NGC 1309 before and after SN 2012Z. The left panel shows an image of NGC 1309 taken by Hubble (before the explosion). The top middle panel shows an enlarged image of the position of the supernova in the image before the explosion. The upper right corner shows SN~2012Z from the 2013 visit. The lower middle panel shows the position of SN~2012Z in the latest observations in 2016. The lower right panel shows the difference between pre-blast images and 2016 observations

The discovery that SN 2012Z is ​​radiating violently after its own supernova leaves no doubt that in some, if not many, cases, white dwarfs can remain intact even after fusion.

Exactly why this particular star not only didn’t explode on its own, but came back even brighter, is something of a mystery.

The researchers behind the discovery speculate that the explosion simply shook things up, allowing its material to return to a less dense, more bloated form.

At a larger volume, the cooling remnants of a white dwarf look even brighter than ever.

“The implications for Type Ia supernovae are very profound,” says McCully.

“We found that supernovae can at least grow to their limits and explode. However, explosions are weak, at least sometimes. Now we need to understand what makes a supernova fail to become Type Iax, and what makes it successful as Type Ia.”

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