Small stars like our Sun die beautifully, surrounded by beautiful veils of multicolored gases that were once their outer layers, leaving only their relic cores as silent testimony to the Universe that they once existed. Our Sun, like other small stars, will first become a bloated red giant that it will grow in size to the terrifying point that its flames will engulf the inner planets Mercury, Venus, and possibly Earth. Then it will wither into a tiny, dense white dwarf–its core shape. In March 2020, an international team, led by astronomers from the University of Warwick (UK), reported that they had discovered a strange phenomenon involving a duo of these dead stars dancing very closely. Scientists detected a huge white dwarf star with a strange carbon-rich atmosphere that could actually be two white dwarfs that merged while performing their strange macabre dance in the space between the stars, narrowly escaping explosive destruction.

Astronomers detected an unusual ultramassive white dwarf located about 450 light-years from Earth with an atmospheric composition that has never been seen before. This important observation marked the first time that a fused dance duo from white dwarfs it had been discovered by astronomers using its atmospheric composition as a clue to solve the mystery of its true identity.

The discovery, published in the March 2, 2020 issue of the journal nature astronomycould shed new light on the lingering question of just how massive white dwarf stars evolve, as well as the number of supernovae that inhabit our barred spiral Milky Way.

Tea ultramassive White Dwarf, named wd J0551+4135was detected in a survey of data derived from the European Space Agency (ESA) gaia telescope. The astronomers followed up their discovery with spectroscopy obtained using the William Herschel Telescope. Scientists focused on those white dwarfs identified as especially massive, an achievement made possible by the Gaia Mission. By breaking down the light emitted by the strange star, astronomers were able to determine the chemical composition of its atmosphere and found that it contained an unusually high level of carbon.

Lead author Dr Mark Hollands, from the University of Warwick Department of Physics, explained in a March 2, 2020 University of Warwick press release that “This star stood out as something we had never seen before. You might expect to see an outer shell of hydrogen, sometimes mixed with helium, or just a mixture of helium and carbon. You don’t expect to see this combination of hydrogen and carbon when At the same time there should be a thick layer of helium in the middle that prohibits it. When we looked at it, it didn’t make sense.”

The majority white dwarfs they are relatively light, weighing about 0.6 times the mass of our Sun. However, WD J0551+4135 weighs an impressive 1.14 times the mass of the Sun, making it nearly twice the average mass of other white dwarfs Despite being more massive than our Sun, it is compressed into a small dense ball that is only two-thirds the diameter of Earth.

To solve the intriguing mystery, astronomers-detectives decided to find out the true origins of the star. The age of WD J0551+4135 it also provided them with an important clue. Older stars orbit our Milky Way much faster than younger ones, and this strange white dwarf traveled our galaxy faster than 99% of the others nearby white dwarfs with the same cooling age. This means that this dead star is much older than it seems.

Dr. Hollands continued to explain on March 2, 2020 University of Warwick press release that “We have a composition that we cannot explain through normal stellar evolution, a mass twice the average for a white dwarf, and a kinematic age greater than that inferred by cooling. We are pretty sure how a star forms a white dwarf and shouldn’t do this. The only way to explain it is if it was formed through a merger of two white dwarfs”.

The death of a small star similar to the Sun

white dwarfs they are all that are left of stars, like our own Sun, after they have finished burning all of their necessary supply of nuclear fusion fuel. At this fatal point, the dying little star has shed its outer gaseous layers into space. of a little star Grand finale contrasts with the noisy and explosive disappearance of more massive stars, which die in violent and catastrophic supernova explosions. Little stars like our Sun “come sweetly into that good night” and perish in great beauty and relative peace. In fact, their beautiful multicolored gaseous shrouds have inspired astronomers to refer to them as the “butterflies of the Universe”, as a tribute to their celestial beauty.

Lonely little stars like our Sun gently perish. However, if there is another star actor in the drama, terrible complications develop. If a small star resides in a binary system with another star, a wild party will inevitably occur. When the first of the duo “dies”, leaving his dense white dwarf core behind, the stellar corpse will gravitationally absorb material from its still-living, victim companion star. like the vampire dwarf it continues to steal more and more material from its unlucky partner, eventually it will absorb enough material to reach enough mass to “go critical”. At this point, the white dwarf he pays for his crime and exploits, just like the big ones. This explosion is called Type Ia supernovaand differs from Type II supernovae from core collapse experienced by more massive stars.

the proposal that WD J0551+4135 is actually an object that was formed as a result of the merger of a duo of white dwarfs it is based on a related, but not identical, theory of their formation. In this case, as one of the two stars expanded at the end of its life into a bloated red giantengulfed its companion star, bringing its orbit closer and closer as the first star withered in its orbit. white dwarf internship Then encore performance ensued when the other star became a bloated red giant. Over billions of years, the emission of gravitational waves further reduced the orbit, to the point that the dancing stellar duo merged to form a single object.

The dancers and their dance

Although white dwarf mergers have been predicted to occur, involving the unusual WD J0551+4135 it’s weirder than expected. This is because most of the mergers in our Milky Way Galaxy occur between stars that have different masses, while this strange merger probably occurred between a duo of stars of similar size. There is also a limit to the size of the resulting single. white dwarf Cam be. This is because, if the resulting stellar corpse weighs more than 1.4 times the solar mass, it will “go critical” and shatter in an instant. Type Ia Supernova burst. However, it is possible that such fatal stellar explosions could be triggered at slightly lower masses, so this strange white dwarf is especially useful because it demonstrates how massive a white dwarf it can arrive and still “live” to tell the story.

Because the merger restarts the star’s cooling process, it is difficult for astronomers to calculate the true age of the star. The stellar corpse probably merged about 1.3 billion years ago, but the original dead star duo may have existed for many billions of years before that event.

WD J0551+4135 is important because it is one of only a handful of fused white dwarfs to be identified, and it is the only one that has been identified so far on the basis of its composition.

Dr. Hollands explained on March 2, 2020 University of Warwick press release that “there are not so many white dwarfs so massive, although there are more than you’d expect to see, implying that some of them were probably formed by mergers.”

“In the future, we may be able to use a technique called asteroseismology to learn about White dwarf composition of the core from its stellar pulsations, which would be an independent method that would confirm that this star was formed from a merger. Perhaps the most exciting aspect of this star is that it almost failed to explode as a supernova: these gigantic explosions are really important for mapping the structure of the Universe, as they can be detected at very great distances. However, there remains a lot of uncertainty about what kind of star systems reach the supernova stage,” he added.

“Oddly enough, measuring the properties of this ‘failed’ supernova and its future appearance tells us a lot about the paths to thermonuclear self-annihilation,” Dr Hollands continued.

This research is published in the March 2, 2020 issue of the journal nature astronomy under the title Year Ultramassive white dwarf with a mixed atmosphere of hydrogen and carbon as a probable remnant of the merger.

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