A duo of dancing stars
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 increase in size to the frightening 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 form. 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. The 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 solving 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 how massive white dwarf stars evolve, as well as the number of supernovae inhabiting our barred-spiral Milky Way.
Tea ultramassive White Dwarf, called 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 a spectroscopy obtained using the William Herschel Telescope. The 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 Department of Physics at the University of Warwick explained on a March 2, 2020 Warwick University Press Release that “This star stood out like something we’ve 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 at 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.”
Most white dwarfs they are relatively light, weighing about 0.6 times the mass of our Sun. However, WD J0551+4135 it 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, the astronomer-detectives decided to discover 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 appears.
Dr. Hollands went on to explain on March 2, 2020 Warwick University 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’re 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 is left of the stars, like our own Sun, after they have finished burning their entire necessary supply of nuclear fusion fuel. At this fatal point, the small dying star has flung its gaseous outer layers into space. That of a little star Grand finale contrasts with the loud and explosive demise of more massive stars, which die in violent and catastrophic supernova explosions. Small stars like our Sun “enter 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.
Little lonely 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 its dense white dwarf core behind, the stellar corpse will gravitationally absorb material from its still-living, victimized companion star. like the vampire dwarf it continues to steal more and more material from its hapless companion, eventually absorbing enough material to reach enough mass to “go critical”. At this point, the white dwarf He pays for his crime and explodes, just like the big ones. This explosion is called Type Ia supernovaand differs from type II supernovae due to core collapse experienced by more massive stars.
the proposal that WD J0551+4135 is really an object that was formed as a result of the fusion of a duo of white dwarfs it is based on a related, but not identical, theory of its formation. In this case, as one of the two stars expanded at the end of its life into a swollen red giantengulfed its companion star, drawing its orbit closer and closer as the first star withered in its orbit. white dwarf internship. An encore performance then ensued as 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 mergers in our Milky Way occur between stars that have different masses, whereas this strange merger likely occurred between a duo of similarly sized stars. There is also a limit regarding 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 can arrive and still “live” to tell the story.
Because the merger restarts the star’s cooling process, astronomers find it difficult to calculate the star’s true age. The stellar corpse likely merged around 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 merged white dwarfs to be identified, and it is the only one so far identified on the basis of its composition.
Dr. Hollands explained on March 2, 2020 Warwick University Press Release that “There aren’t that many white dwarfs so massive, although there are more than you would expect to see, which implies 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 him White dwarf core composition from its stellar pulsations, which would be an independent method confirming that this star 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 pathways 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.