Rare Event In Space: Extremely Dramatic Merger Of Two White Dwarfs

Eddie Gonzales Jr. – MessageToEagle.com – Many unbelievable phenomena take place continuously in space. Among them, there are the most powerful explosions in the Universe, known as gamma ray bursts that occur once day, powerful quasars believed that they are produced by supermassive black holes and other curious celestial objects.

One of such objects was now identified by astronomers at the University of Bonn and their colleagues from Moscow.

The infrared nebula of J005311. (c) Vasilii Gvaramadse/Moscow UniversityThe infrared nebula of J005311. Image credit: Vasilii Gvaramadse/Moscow University

It is most likely the product of the fusion of two stars that died a long time ago.

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 infrared radiation and no visible light.

“Our colleagues in Moscow realized that this already argued for an unusual origin”, Dr. Götz Gräfener from the Argelander Institute for Astronomy (AIfA) at the University of Bonn, said in a press release.

The object dubbed by astronomers, J005311 is located in the constellation Cassiopeia, 10,000 light-years from Earth.

The infrared nebula of J005311: 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 UniversityThe infrared nebula of J005311WISE 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

“We assume that two white dwarfs formed there in close proximity many billions of years ago. They circled around each other, creating exotic distortions of space-time, called gravitational waves,” Prof. Dr. Norbert Langer from AIfA explained.

In the process, they gradually lost energy. In return, the distance between them shrunk more and more until they finally merged.

In Bonn, researchers analyzed the spectrum of the radiation emitted by the nebula and its central star was analyzed.

The results showed the object has no hydrogen nor helium, and 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.

“Such an event is extremely rare. There are probably not even half a dozen such objects in the Milky Way, and we have discovered one of them,” Dr. Gräfener, said, adding that the simulations showed 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 but before, its collapse will be accompanied by a huge bang, a so-called supernova explosion.

Paper

Written by Eddie Gonzales Jr. – MessageToEagle.com Staff Writer