New type of star discovered? It is a strange one.

[Roger E. Moore]

Study of nebula IRAS 00500+6713 suggests its central star is unlike any seen before. QUOTE: ...The researchers were studying the nebula IRAS 00500+6713 because last year, another team of researchers had discovered a central star, called J005311, with a stellar wind of unusually high speeds. In taking a closer look at the star and its history, the researchers found that it had formed due to a collision between two white dwarves—an event that typically leads to a supernova and annihilation of both stars. Prior research has also shown, however, that when such stars collide, one or both of the stars may survive—and sometimes, they merge. The researchers found evidence suggesting that J005311 had formed as a merger. But the resulting star had unique attributes. It emitted unusual X-rays and was brighter than expected, suggesting it was too massive to be a white dwarf. Further study showed the star to have a unique composition dominated by oxygen and neon. That finding suggested the star was an unstable byproduct of two white dwarves colliding without creating a new white dwarf—instead, a new kind of star was born. The researchers suggest its instability suggests it likely will not last any longer than 10,000 years.

https://phys.org/news/2021-01-nebula...tral-star.html

[publiusr]

A great oxygen source one day, then...

[kpatz]

Seems like a lot of missing information, or still unknown, about this star. It's supposedly not a white dwarf, so is it undergoing core fusion? Is it over or under the Chandrasekhar limit? Perhaps they merged slowly enough so they didn't go boom. What will happen in 10,000 years? A fizzle or a kaboom? Will it end up as a white dwarf or a neutron star?

[Roger E. Moore]

Cosmic Neon Lights: Strange New Type of Star Revealed in X-ray Light. A team of astronomers led by Lidia Oskinova of the University of Potsdam, Germany, used ESA’s XMM-Newton X-ray telescope to study the object that was originally discovered in 2019. Back then, astronomers already reported that the object has very high wind speeds and is too bright, and therefore too massive, to be an ordinary white dwarf. They suggested that the object is a new type of star that survived the merger of two white dwarfs.Based on new information from XMM-Newton, Lidia and her team now suggest that what we see in the image is a new type of X-ray source powered by the merger of two white dwarfs. The remnant of the clash – the nebula – is also visible in this image, and is mostly made out of the element neon (shown in green). The star is very unstable and will likely collapse into a neutron star within 10,000 years.

https://scitechdaily.com/cosmic-neon...n-x-ray-light/

[cjameshuff]

Seems like a lot of missing information, or still unknown, about this star. It's supposedly not a white dwarf, so is it undergoing core fusion? Is it over or under the Chandrasekhar limit? Perhaps they merged slowly enough so they didn't go boom. What will happen in 10,000 years? A fizzle or a kaboom? Will it end up as a white dwarf or a neutron star?

https://www.aanda.org/articles/aa/fu...a39232-20.html

It sounds like it's over the Chandrasekhar limit, with signs that it was burning carbon and oxygen in the past (possibly with a supernova Iax), and its wind may be due to a C-burning shell on a core of O and Ne.

My impression is that the core is not fusing at all or not fusing enough to support itself, and will collapse after it cools a bit from the events of the merger, with a core-collapse supernova that ends with a neutron star remnant.

[kpatz]

I googled J005311 and found some more articles that may shed a little more light on the makeup of this unusual star. For example: https://cosmoquest.org/x/2021/01/new...istant-nebula/

It seems to be a merger of a C+O and a O+Ne white dwarf, which somehow survived the supernova explosion that normally would have obliterated it. It's thought to be undergoing carbon fusion which is keeping the core from collapsing and this is producing the large amount of X-rays. Once it runs out of fuel, it will collapse into a neutron star.

If there was a supernova when the stars collided, and another one occurs when the core collapses in around 10,000 years, would this be the first known instance of the same star(s) producing two supernovas?

[cannongray]

It is not known exactly why it is so unusual. Scientists believe that this is due to the proximity of another "red dwarf" star, which is orbiting. It affects the magnetic field of stars and produces an unusual effect.

[cjameshuff]

It is not known exactly why it is so unusual. Scientists believe that this is due to the proximity of another "red dwarf" star, which is orbiting. It affects the magnetic field of stars and produces an unusual effect.

What? No, that has nothing to do with this star.