2020-07-02

75 million light-years away, a star mysteriously disappears, scientists may admit new theory

By ddzyx

Water is active, trees have roots, and there is a reason why an object disappears.

But recently, scientists have discovered that a celestial body in the universe has mysteriously disappeared, and no reason can be found.

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PHL 293B is a dwarf galaxy. A few decades ago, scientists discovered a special star here. They believe that this star is likely to have entered the end of evolution and is about to die, so they pay more attention to it. In the ten years from 2001 to 2011, its brightness has been changing, and scientists have also recorded it.

Wait, can our observation ability see stars so far away?

In general, no. 75 million light-years are too far away for us, generally at this distance, we can only identify the whole galaxy, but not the stars. However, some very bright stars, even if they are so far away, can still be observed by us, such as this Luminous Blue Variable star.

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The high-luminosity blue variable star, also known as the S-shaped variable star Swordfish, is a very bright, blue Supergiant variable stars can reach 150 times the mass of the sun, close to the theoretical upper limit of the star’s mass. This star is at the end of its evolution, so although its brightness can reach one million times that of the sun, it is very unstable and changing. Especially when the supernova erupts, the brightness and spectrum of the high-luminosity blue variable star will undergo dramatic changes.

In the early days of our observation of the dwarf galaxy PHL 293B, it was through its characteristics that the brightness of the sun was more than 2.5-3.5 million times that of the sun to discover the star. This signal is very obvious.

However, when astronomers of the European Southern Observatory aimed all four optical telescopes of the Very Large Telescope Array at PHL At 293B, he was so surprised when he didn’t find any trace of it. Where did it go? Is it dead?

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Astrophysicist Andrew Allan of the Trinity University in Dublin, Ireland said:”A star of this magnitude, It disappeared without a dazzling supernova explosion, which is very strange.”

Scientists will soon go back to collate the observations of the star from 2011 to 2016, hoping to be able to Some clues were found, but the result was even more confusing. In 2011, the observation data showed that its light can still be observed. But after 2011, without knowing the reason, it suddenly disappeared completely.

As the saying goes, even if a thing hits the water, it should always be heard, let alone a huge star? Even if it is dead, should the body be left behind?

It seems that a more reasonable explanation is that it becomes a black hole, because only black holes make it difficult for us to observe. But the problem is coming again. According to existing theory, a star that wants to collapse into a black hole will first experience a supernova explosion. This process is very dramatic and cannot be missed by us. So some people have speculated:Could it just collapse without experiencing a supernova explosion?

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Although this conjecture sounds a bit bizarre, the universe is so mysterious, who can be sure What? Therefore, some scientists have thought about this in depth.

Allan said:”If this is really the case, it will be the first time we have directly observed a huge star ending our life in this way.”

Actually In the past few years, there are indeed theories that some stars can collapse directly into black holes without going through the process of supernova explosion. For example, in 2017, someone published a paper describing a similar phenomenon in a galaxy 22 million light years away. At that time, a red giant star quickly disappeared without a trace after the brightness suddenly increased. At that time, some scientists believed that this star may have experienced an unsuccessful supernova explosion before exploration, and finally collapsed and ended up hastily.

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The star in PHL 293B has suddenly disappeared, making people have to think of this new theory and the 2017 paper. Perhaps, like the red giant star three years ago, it was not able to complete the curtain call performance, but directly exited.

In general, scientists have made three guesses.

The first speculation is that this star is just entering the end of evolution. When it gradually loses its light and sprays matter into the surrounding universe, there is a cloud of dust that covers it. This statement is also used by some people to explain the phenomenon of red supergiant star in the Milky Way, which has become darker in recent years ( Of course, this statement has yet to be confirmed). At present, Senju IV has gradually recovered a bit of brightness. These people think that it is because the dust cloud has dispersed, and the high-luminosity blue variable star It was not so good luck, the entire death process was carried out in the thick cloud, which caused us not to observe.

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(Picture description:The highest HD so far in Sanju 4 (Photo)

However, scientists using near-infrared light to observe the dwarf galaxy PHL 293B from 2009 to 2019 show that at least the possibility of high-temperature dust clouds has been ruled out. However, due to the lack of observations in the mid and far infrared bands, the possibility of low-temperature dust clouds cannot be ruled out.

Another speculation:it has indeed completely closed the curtain, suddenly ended its life around 2011, and collapsed into a black hole. In addition, it is also possible that its mass is between 85 and 120 times that of the sun. This range is just below a celestial body called pair-instability supernova, in this case , It will be directly shattered after the supernova erupts without collapsing.

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In addition, some scientists believe that it has experienced a normal supernova explosion, but it happens to be ignored by us Within a period of time. However, the probability of this statement is very low. After all, as a high-luminance blue variable star, it can use the afterglow of the explosion to light up a large area around it for at least 5 years after the supernova explosion, instead of It immediately became completely bleak.

As far as the observation data available to scientists are concerned, we can only make so many speculations. If you want to further understand the reason, you must observe it in more bands. Maybe it is still hidden in the mist, maybe it has completely disappeared. If it disappears, where is its remains? These problems are left to the scientists to continue to explore.