Stellar waltz with dramatic ending

Stellar waltz with dramatic ending
The infrared nebula of J005311. Credit: Vasilii Gvaramadse/Moscow University

Astronomers at the University of Bonn and their colleagues from Moscow have identified an unusual celestial object. It is most likely the product of the fusion of two stars that died a long time ago. After billions of years circling around each other these so-called white dwarfs merged and rose from the dead. In the near future, their lives could finally end—with a huge bang. The researchers are now presenting their findings in the journal Nature.

The extremely rare merger product was discovered by scientists from the University of Moscow. On images made by the Wide-field Infrared Survey Explorer (WISE) satellite they found a gas nebula with a bright star in its center. Surprisingly, however, the nebula emitted almost exclusively and no visible light. "Our colleagues in Moscow realized that this already argued for an unusual origin," explains Dr. Götz Gräfener from the Argelander Institute for Astronomy (AIfA) at the University of Bonn.

In Bonn, the spectrum of the radiation emitted by the nebula and its was analyzed. In this way, the AIfA researchers were able to show that the enigmatic celestial object contained neither hydrogen nor helium—a characteristic typical for the interiors of . Stars like our Sun generate their energy through hydrogen burning, the nuclear fusion of hydrogen. When the hydrogen is consumed, they continue burning helium. However, they cannot fuse even heavier elements—their mass is insufficient to produce the necessary high temperatures. Once all helium is used up, they cease burning and cool down turning into so-called white dwarfs.

Usually their life is over at this point. But not for J005311—this is how the scientists named their new find in the constellation Cassiopeia, 10,000 light-years from Earth. "We assume that two white dwarfs formed there in many billions of years ago," explains Prof. Dr. Norbert Langer from AIfA. "They circled around each other, creating exotic distortions of space-time, called gravitational waves." In the process, they gradually lost energy. In return, the distance between them shrunk more and more until they finally merged.

Stellar waltz with dramatic ending
WISE 22 micron infrared images at different intensity scales (panels a and b) compared with an optical IPHAS H alpha image where the nebula is not visible (panel c). (c) Vasilii Gvaramadse/Moscow University

Only five of these objects in the Milky Way

Now their total mass was sufficient to fuse than hydrogen or helium. The stellar furnace started burning again. "Such an event is extremely rare," stresses Gräfener. "There are probably not even half a dozen such objects in the Milky Way, and we have discovered one of them."

An extreme stroke of luck. Nevertheless, the researchers are convinced that they are right with their interpretation. For one, the star in the center of the nebula shines 40,000 times as bright as the sun, far brighter than a single white dwarf could. In addition, the spectra indicate that J005311 has an extremely strong stellar wind—this is the stream of material that emanates from the stellar surface. Its engine is the radiation generated during the burning process. Only, at a speed of 16,000 kilometers per second, the wind of J005311 is so fast that this factor alone is not enough to explain it. However, merged white dwarfs are expected to have a very strong rotating magnetic field. "Our simulations show that this field acts like a turbine, which additionally accelerates the stellar wind," says Gräfener.

Sadly, the resurgence of J005311 will not last long. In only a few thousand years the star will have transformed all elements into iron and fade again. As its mass has increased to more than 1.4 times the mass of the Sun in the merger process, it will suffer an exceptional fate. The star will collapse under the influence of its own gravity. At the same time, the electrons and protons building up its matter will fuse into neutrons. The resulting neutron star has only a fraction of its previous size, measuring only few kilometers in diameter, while it is weighing more than the entire solar system.

J005311, however, won't leave without a final salute. Its collapse will be accompanied by a huge bang, a so-called supernova explosion.


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More information: Vasilii V. Gvaramadze et al. A massive white-dwarf merger product before final collapse, Nature (2019). DOI: 10.1038/s41586-019-1216-1
Journal information: Nature

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Citation: Stellar waltz with dramatic ending (2019, May 21) retrieved 20 August 2019 from https://phys.org/news/2019-05-stellar-waltz.html
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May 21, 2019
3000 year it may supernova and it is only 10K years away. That is close enough that it can have a radiation effect on Earth and within human time. Our history is longer than 3000 years. The 10000 light years distance is only important as an attenuation indicator. The light we see now is telling us there is 3000 years to go, so we dont get another 10000 years safety. The supernova is already on its way.

May 22, 2019
don't sweat it ace.
By time the first high-powered radiation hit's this System & the Earth?
Followed up by centuries of slower-moving pulses of less energetic radiation?

Followed in turn by millennia of bombardment by space debri?.

Don't worry, be happy!
By then?
This world will be populated only by GOP Morlocks.
They will have eaten everyone else.

It amuses me to imagine the rapaciously sanguine vermin being bitch-slapped by their,
so richly deserved,
Cosmic karma.

"I am of course,
most sincerely,
faking optimism..."

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