The newly discovered type of stellar explosion may help us to better study the thermonuclear explosions of dead stars.
This new phenomenon is called micronova and occurs on the surface of white dwarf stars that are actively absorbing matter from a nearby binary companion star. Accumulation of matter in the white dwarf causes localized thermonuclear explosions – micronova.
As astronomers have observed, during these explosions, tens and hundreds of quintillion kilograms of stellar matter burn in a matter of hours.
According to researchers, this mass is several billion times the mass of the Pyramid of Khufu. If you prefer a different comparison – about a tenth of the mass of the moon.
“For the first time in history, we discovered and revealed an event called Micronova. This phenomenon calls into question our notion of thermonuclear explosions in stars. “We thought we knew about it, but this discovery offers a whole new way of making it happen,” said Simon Scarring, an astrophysicist at the University of Durham in Britain.
White dwarfs in near-binary systems act as a kind of thermonuclear explosion machine. White Dwarf e. წ. A dead star is a residual, collapsing nucleus that remains from a main-sequence star after it has run out of fuel and removed the outer part of matter. In different mass classes, other stellar debris of this type are neutron stars and black holes.
The collapsed core is very dense. The mass of white dwarf stars is about 1.4 times the size of our Sun and is about the size of Earth. Many of them are found in binary systems.
In rare cases, the stars in the dual systems are so close together that the white dwarf absorbs matter from a neighboring companion, which e.g. წ. Novad causes an explosion. A total of about a dozen such near-double systems have been found in Deer Leap.
When such two stars move around each other, matter, mostly hydrogen, the smaller, denser white dwarf removes the other large star and joins itself. This hydrogen accumulates on the surface of the white dwarf and heats up.
Periodically, the mass increases so much that the pressure and temperature in the lower layer are high enough to cause a thermonuclear explosion, during which time the excess mass of the star will be ejected into space. This event is called Nova.
Scarring and his team found that Micronova was a small version of this explosion.
White dwarf micronova were first discovered by researchers in the data of the TESS Telescope, which hunts exoplanets. TESS is optimized to see even very small variables in the light of exoplanet stars. As it passes in front of the star, the exoplanet dims its light very slightly.
In the TESS data, a group of researchers discovered a micronova when they noticed a sudden glow in the light of a white dwarf star, not a darkening. Because of this, similar white dwarfs began to search for similar events. In total, they found three explosions, in the third of which, following observations, they discovered a previously unknown white dwarf star.
However, the inflammations were too small and could not be nova, which is a much more powerful and long-lasting phenomenon. Therefore, the group began to search for a scenario that could be explained by observations. They came to the conclusion that most of this phenomenon was explained by Micronova.
When a white dwarf with a strong magnetic field is in the near binary system, the companion star absorbs matter. The magnetic field of this matter travels to the poles of the white dwarf, where it accumulates and gradually explodes, similar to the typical white dwarf Nova, but on a much smaller scale.
“For the first time in history, we have seen that hydrogen can be synthesized in a localized way. Hydrogen fuel in some white dwarfs may be at the base of magnetic poles and therefore, synthesis can only occur at these magnetic poles. “It causes microsynthetic bombs to explode, which have only about one millionth of Nova’s explosive power, and we call them micronova,” said Paul Grutt, an astronomer at the University of Redbudd in the Netherlands.
This discovery may solve a mystery that has existed for decades. In one of the double white dwarfs, called TV Columbae, similar inflammations have been observed for 40 years. Over the years, similar explosions have been observed in other highly magnetized white dwarfs. A new explanation may finally offer a convincing answer.
The discovery indicates that such explosions may be quite common, but astronomers need more observations to study them in more depth.
“We see once again how dynamic the world is. These events can be quite common, but because they happen so quickly, it is difficult to catch in action, “said Simon Scarring, an astrophysicist at the University of Durham in the United Kingdom.
The study was published in the journal Nature.
Prepared according to eso.org and ScienceAlert.