Image source: NASA
8 hours ago
The explosion of the white dwarf star “T Coronae Borealis” or the northern crown star. It happens every 80 years.
The world’s attention was originally focused on the impending total solar eclipse. But in fact This year there is another phenomenon that may be even more interesting. Because of the constellation Northern Crown It consists of a white dwarf and an ancient red giant. The countdown to the spectacular nova explosion is underway.
The constellation Northern Crown or Corona Borealis is 3,000 light years away from Earth and the star that will explode is The white dwarf star is named “T Corona Borealis” or “T CrB” for short, which NASA points out. This nova explosion It will be a phenomenon that you may only see once in your entire life.
This nova explosion phenomenon It is expected to occur before September this year and is likely to be visible to the naked eye. without needing to use an expensive telescope in any way
T CrB explosions occur only every 80 years, and the last time this occurred was in 1946.
“I am very excited. It’s like waiting to see Halley’s Comet. That comes around every 75-80 years, just a nova explosion. “Comets often don’t get a lot of attention,” said William J. Cook, NASA’s meteorite environment program manager. “The media tends to focus more on comets.”
Scientists predict how a nova will form.
Naturally, NASA experts don’t know when a nova explosion will occur, but there are 10 nova events that we know of. “Repeating nova”
“Repeating novae are novae that occur over a period of time. There will be more explosions,” Cook explained. “Corona borealis is a good example.”
So how does NASA know when T CrB will explode? They use mathematical calculations and empirical evidence. For example, the Corona Borealis explosion occurred in 1946, or 78 years ago. That means The clock is counting down.
Another sign that T CrB is close to exploding is that “we know that before the nova, The star will fade out in about a year, with the Corona Borealis starting to fade in March 2023, so we think it’s close to exploding. Between now and the end of September,” Cook said.
Image source: NASA
T CrB’s repeated nova explosion rate also makes this star’s explosion unique from other novae discovered in recent years.
Meredith McGregor is an assistant professor in the Faculty of Physics and Astronomy. Johns Hopkins University which specializes in star activities Express your opinion on this matter: “We discovered a lot of novae. But most are not recurring novae. Or it would take a long time to explode again. Until we don’t know when it will happen.”
Richard Townsend, professor of astronomy University of Wisconsin-Madison added that the timing of repeated nova explosions is uncertain. They could be a year or even millions of years apart.
What causes a nova explosion?
In addition to predicting the time of the nova phenomenon, NASA experts also know that Why do novae occur? For example, the white dwarf T CrB is a binary star system, meaning it is one of two stars orbiting each other. Another star in the same system is a red giant star
White dwarfs contain material similar to that of the Sun. But its radius around the star is more than 100 times smaller than the sun’s, making it about the same size as Earth. But with the material packed into small stars This makes the white dwarf’s gravitational force extremely great.
And when red giant stars that orbit together release matter The gravitational force of T CrB will attract or accumulate that material and store it on the surface of the star itself. When accumulated over many years The amount of matter sucked in had reached its limit.
“What is happening in this binary star system is Red giants dump material onto the surface of the white dwarf,” Cook said. It also causes a thermonuclear reaction. Just like a landmine explodes. Make the white dwarf explode to release this material.”
Townsend gave a similar explanation, saying that when large amounts of material accumulate on T CrB and temperatures rise to millions of degrees Celsius, The nuclear fusion reaction will begin. causing observable nova explosions
“This is also a reaction that is taking place in the sun’s core. because of the red giant star It released a huge amount of energy onto the surface of the white dwarf,” Townsend said. This causes white dwarfs to briefly appear brighter than red giants. which the light from the two stars When viewed from the world will increase primarily 1,000-100,000 Just the same amount.”
This huge explosion It helps NASA experts understand the mass transition that occurs between two stars in binary systems. and thermonuclear explosions That happens when a white dwarf stars nova. which these processes It happens over and over again in this binary star system.
“Normally it takes thousands of years for you to see a nova explosion like this, but T CrB happened earlier than that. Makes it a rare nova,” McGregor said.
What will you see when a nova occurs?
T CrB has a visibility magnitude of +10 in brightness, according to NASA. But when the nova explosion occurred The visual acuity increases greatly, reaching level +2, which is much brighter than level +10.
If compared to make it easy to understand The +2 visible magnitude is equivalent to the brightness of the North Star, or Polaris. This means that When a nova explosion occurs The naked human eye can see it.
For those wanting to see the T CrB nova explosion, NASA recommends looking to the constellation Northern Crown. It is located near the constellations Boots and Hercules. “This is where the nova explosion happened. It will appear like a bright new star rising in the sky.”
If you see a light like a new star in the sky Must understand that This is not the birth of a new star. because of nova explosions and nuclear reactions It only allows us to see T CrB more clearly.
“This phenomenon is caused by an existing star. We’ve just seen something like the birth of a new star. Just because it’s normal We can’t see this star,” McGregor explains. “White dwarfs are so small they can’t be seen with the naked eye. But because of the fusion reaction that occurs It allows us to see it for a moment.”
Cook points out that when T CrB shines at its peak, It will be brighter than Mars. and will continue to shine brightly in the sky Until visible to the naked eye for another 2-3 days, although the nova explosion lasted for more than a week.
When it all ends That is, the white dwarf removes material from the red giant and T CrB fizzles out, becoming invisible to the naked eye for decades.
