The mystery of nova! For the first time, mankind unveiled the mystery of nova explosion.

Nova explosion is the most brilliant stage in the life of binary system. This process usually lasts for weeks or even months, accompanied by dazzling light. Although they are not uncommon-there are about 10 nova explosions in the Milky Way every year-this is the first time astronomers have observed them completely.

This is the first time in human history.

The explosion occurred in a closed binary system. One of the stars has completed the journey of a red giant, leaving a remnant of a white dwarf. When its companion star moves to the near point, the huge gravity of the white dwarf will strip a lot of matter from the star, most of which is hydrogen.

This hydrogen accumulates on the surface of white dwarfs, forming a thin atmosphere. The radiant heat of white dwarfs heats up this layer of hydrogen, and finally the gas reaches the pressure threshold, thus triggering hydrogen nuclear fusion. Do not underestimate this layer of hydrogen. Under such conditions, it will have an explosive and violent fusion reaction.

Accompanied by fusion, it is dazzling light and the hydrogen layer of the rapidly escaping white dwarf. In the past, because of this creation-like starlight, astronomers once thought that these spots meant the birth of new stars. So I always use the name "Nova".

Now these types of nova are called "classic" nova. (When a white dwarf repeats this process, it is called a "circulating nova")

In the universe, this is a high-energy event. It will produce a lot of gamma rays, X rays and visible light. Therefore, during the nova explosion, some stars that could only be seen through telescopes can be seen with the naked eye.

All these are widely accepted in astronomy and astrophysics. But most of them are theoretical.

Astronomers using BRITE constellation satellites were lucky enough to observe the whole process from beginning to end and confirmed this theory.

BRITE is a nanosatellite constellation, which aims to "study the star structure and evolution of the brightest star in the sky and its interaction with the local environment".

They work in low earth orbit, and there is almost no limit to the part of the sky that can be observed. This observation of nova is purely coincidental.

This satellite system spent several weeks observing the 18 star in karina constellation. On this day, a new star appeared. Reina kushner, the British operations manager, found a new star in his daily inspection.

This observation of nova is purely coincidental. This satellite system spent several weeks observing the 18 star in karina constellation. On this day, a new star appeared. British observer Reina kushner found it in her daily observation.

"A star suddenly appeared in our film, and there was no relevant result in previous records," he wrote in a press release. "In my years of work, I have never seen such a thing!

Werner Weiss from the Department of Astrophysics of Vienna University emphasized the importance of this observation at the press conference.

"But what caused the previous humble star explosion? This problem has not been satisfactorily solved so far, "he said.

The explosion of karina nova V906 provided an answer for researchers and also confirmed some theoretical concepts behind the explosion of nova.

The earliest observation of V906 in Carina was the supernova all-sky automatic measuring instrument. Fortunately, it appeared in a star field observed by BRITE for several weeks, so BRITE recorded a lot of nova data.

"It's great to be able to observe the whole process of supernova explosion through satellite!" Otto Koudelka, German Tugstat- 1 project manager, said.

The V906 is about 13000 light years away from the Earth, so this explosion has long been a historical relic. "After all, this new star is too far away from us, and it takes about 13000 years for starlight to reach the earth," Weiss explained.

The BRITE team presented their findings in a new paper. The title of the paper is "The shock wave of nova is the direct evidence to drive light emission", which was published in the journal Nature Astronomy. The first author is Elias Eddy of Michigan State University.

Konstanz Zwentz, head of the British scientific team at the Institute of Astrophysics and Particle Physics at Innsbruck University, explained: "This observation shows that we can record supernova explosions with unprecedented accuracy."

Zwin immediately realized: "What we have now is the unique observation material in the world".

A nova explosion like V906 karina is actually a thermonuclear explosion on the surface of a white dwarf. For a long time, astrophysicists believe that the light of nova is powered by the continuous surface nuclear reaction after the explosion. But the data from BRITE shows that this does not seem to be the only answer.

In this new paper, the author points out that the shock wave generated when the nova collapses is more important than expected. The author said, "The shock wave generated by the nova jet may determine the brightness of the nova."

The author thinks that these shock waves may also affect other events, such as supernova explosion, star fusion and destructive tidal events. But there is no evidence of direct observation.

"Through the synchronous observation of space-based optics and gamma rays of the new star v 906(ASASSN- 18fv) in 20/8 years, we think that the peak positions of these two bands are obviously related."

Because these peaks appear at the same time, it means that the shock wave may be the energy source of new starlight.

"At the peak, the brightness of Nova almost doubles, which means that most of the brightness is driven by shock waves. Therefore, the light of the nova is not from the nuclear reaction on the surface, but is driven by the shock wave generated during the explosion.

"The spectrum we collected ranges from infrared rays to gamma rays, which undoubtedly proves that shock waves are the driving source of brightness changes during nova explosions and other optical transients.

In a broader sense, we have proved that shock waves play an important role in events like nova explosion. But in the past, this understanding was largely based on the speculation of brightness and time. This study is the first direct observation of this shock wave, and people are likely to continue to observe it in the future until the role of the shock wave can be determined.

In the conclusion of the paper, the author wrote: "Our observation results of Nova V906 clearly show that in the explosion transient, a large amount of absorbed energy shock wave can produce a large amount of visible light and light of other wavelengths."

"Through all-weather observation of modern technologies, such as ASAS-SN (Automatic Supernova Explosion Investigation System), zwicky Transient Facility (ZTF) and Vera C Rubin Observatory, we will find more and brighter transients than before. By studying the new stars in the backyard of our galaxy, we can find the physical principles that drive these distant and strange astronomical events.

Author: Evan Goff, Universe Today

Fiscal year: 27,000.

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