In 2024 there will be a once in a lifetime stellar explosion visible from everywhere!
In the constellation Corona Borealis, there is a very special star called T Coronae Borealis,
better known by its acronym (T CrB). This star is
actually a binary system containing two stars that are very different.
But what's so special about this binary star? Recently, a group of scientists from Louisiana
State University published a study on this star in the Journal for the History
of Astronomy. In that article, they explained that this star could be about to experience a
colossal explosion known as NOVA in 2024. But what is a nova, and how do we know
precisely when it will happen? Stay with us to find out!
T coronae borealis (T CrB) This is a 10th-magnitude binary star,
meaning it is not visible to the human eye and is barely visible to amateur telescopes.
(T CrB) It is a binary star, meaning it is not a star but a star system of two different stars.
It is known that most of the stars in our galaxy are of this type. There are theories that,
in the past, billions of years ago, the Sun may have had a companion, and both the sun and its
companion mounted around a common center of mass. Today, this theory is still open in the
scientific community, and many astronomers consider the possibility that the Sun had a
companion in the Sun's past very likely. Binary stars are exciting in scientific
research because each star that makes up the system can influence the other differently.
The stars that make up a double star system are usually called "components," and each
component has different characteristics. The binary system (T CrB) comprises a
red giant star and a white dwarf star. The system's two components orbit around
a common center of mass every 228 days. The orbit is nearly circular and tilted at an angle of 67°.
The two stars are known to be extremely close, separated by only 0.54 astronomical units. To give
you an idea of how close they are, this distance is less than the distance from Venus to the Sun.
In other words, the two stars are so close that the gravitational
effects of one influence the other. The biggest star in the system is a
red giant in its last stage of life before becoming a white dwarf. On the other hand,
the hottest component of the system is a white dwarf surrounded by an accretion disk.
This accretion disk is the factor that produces novae, but how exactly are they produced?
Origin of novae A nova is a transient astronomical event
that causes the sudden appearance of a bright, apparently "new" star. Hence, its name, "nova,"
which in Latin is written "nueva" and means new. This appearance of a "new" star is temporary
and can last for weeks or months. But as we mentioned, it is not the appearance of a new star,
but rather a phenomenon that unleashes a brightness, which, seen from Earth,
gives the impression that a new star appeared. But how does a nova occur?
A nova forms from two main-sequence stars in a binary system. Normally,
the stars in a binary system are very similar. However, most of the time, one of the two stars
will have a greater mass than the other, so the star that has more mass will consume its fuel
faster and reach its final stage of life sooner. When one of the two stars evolves into a red
giant, it begins to die, ejecting its outer layers and scattering all the materials it formed
during its lifetime into a planetary nebula. When the star has ejected all its outer layers,
in the end only its core will remain, which we know as a white dwarf, this type of star,
although they seem small and cold, still retain a large amount of mass. The mass of
a white dwarf is comparable to that of the Sun, while its volume is comparable to that of Earth.
However, this new white dwarf is still gravitationally anchored to its sister, which has
not yet reached its last stage of life, and both continue to orbit around a common center of mass.
When the second star reaches its last stage of life, it begins a process similar to the first,
first becoming a red giant and then gradually beginning to free itself from its outermost
layers composed mainly of hydrogen. However, at this stage, something
extraordinary happens: the outer layers released by the second star begin to be
absorbed by its companion, the white dwarf. As a result, the white dwarf constantly captures
matter from its companion's outer atmosphere and begins to form a hydrogen accretion
disk around it. Since the white dwarf is made up of degenerate matter, hydrogen does
not inflate, but its temperature increases significantly, becoming ionized hydrogen.
Hydrogen fusion can occur stably on the surface of the white dwarf, resulting in a super-smooth
X-ray source. Still, hydrogen combustion is usually thermally unstable and quickly converts
into other heavier chemical elements. This creation of elements from hydrogen
causes an exothermic reaction that releases enormous energy. This ejects the remaining
gases from the white dwarf's surface and produces a bright light in an explosion.
This burst is what we call "Nova," a drastic increase in a star's luminosity;
this brightness increase can be remarkably rapid or gradual, so once the burst of light
occurs little by little, the brightness decreases until the star returns to its average brightness.
The time it takes for a nova to decay by about 2 or 3 magnitudes from maximum optical brightness
varies depending on the size of the star. Fast novae will normally take less than
25 days to decay by 2 magnitudes, while slow novae will take more than 80 days.
What type of nova is T Coronae Borealis (T CrB)? T CrB is classified as a "Recurrent Nova"
because it has had different novae with a certain periodicity since this star began to be observed.
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How do we know it will explode in 2024? As mentioned above, T CrB has had
explosions in the past that are currently recorded by the American Association of
Variable Star Observers, or AAVSO. The first occurred on May 12, 1866,
and the second on February 9, 1946. Both events were T CrB explosions;
they reached a magnitude of 2 and were bright enough to be observed with the naked eye.
The astronomers discovered, however, that before the star's luminosity increases,
it decreases its brightness a bit. In his research, scientist Justin
D. Linford of the Department of Physics and Astronomy of West Virginia University analyzed
the star's state of activity between 2015 and 2016 and realized that during this period,
the star became much brighter than usual and expelled a more significant amount of X-rays.
The scientists collected information from different radio telescopes and telescopes,
obtaining data with which they could create a model of the star's behavior.
They concluded that the star's behavior today is very similar to what was observed in the
1940s when the last explosion occurred. To corroborate this, they compared the
data obtained with the data from 1938, and the similarity was evident. The way
the star behaved during 2015 and 2016 is very similar to how it behaved in 1938,
eight years before the 1946 nova occurred. According to current records, this corroborates
existing information about past T CrB explosions. In 1945, a year before the 1946 explosion,
astronomers observed that the total brightness of this star decreased by two orders of
magnitude, from +10 to +12. Remember that in astronomy,
the greater the magnitude of a star, the fainter its brightness, so the higher the magnitude,
the more difficult it will be to see with the naked eye. The maximum magnitude that
the human eye can observe is approximately 6 or 7 magnitudes; from those numbers onwards,
our eyes are no longer able to perceive anything; that is, if you try to observe a star of magnitude
8, 9, or 10, you simply will not be able to. That is why this star is very difficult to
observe, as it can only be done with special telescopes or binoculars.
Back to the main point. Just one year after T CrB dimmed its brightness, there was an
explosion that could be observed from Earth as a nova. This explosion increased the brightness
of T CrB until it reached a magnitude of +2, so it could now be seen with the naked eye.
However, on May 11, 1866, astronomer John Birmingham observed this star for the first
time when it suddenly "appeared" in the sky. At the time, Birmingham didn't know it, but in
reality, that star hadn't just appeared; what had happened was that it had just discovered a nova.
It is thought that it is most likely that a day before the discovery of Birmingham,
the star T CrB dimmed its brightness slightly and then gave way to the explosion.
In summary, we have a pattern that repeats before the star is going to explode like a nova;
this pattern is as follows: First, for about a year,
T CrB decreases its brightness and then returns to its initial brightness, then seven years later,
its brightness decreases again for a few months. Finally, a year after the last dimming period, it
explodes in a nova that increases in magnitude up to 8 times and makes it visible to the naked eye.
Astronomers' observations indicate that last year, 2023, T CrB had a decrease in brightness,
just seven years after the last dimming period that occurred in 2016.
This means that T CrB will undoubtedly explode again in 2024 and produce a nova that will
be visible to the naked eye. How and where to observe it?
At Insane Curiosity, we don't like to be sensationalists, so we'll be honest with you:
This event won't be repeated in 80 years! But... Unlike the solar eclipse of April 8, this one will
not be able to be seen so easily. Remember that T CrB is a star of magnitude 10 that is
not visible to the naked eye, and unless you have experience looking for objects with a telescope,
it will be very difficult to find it. We also don't know the exact date on
which it will happen. It is thought that it could happen between April and September of this year,
so there is a margin of several months in which it can happen. When it happens, you should look
for a star of magnitude 2 in the sky. Magnitude 2 stars are not as bright as
you imagine; actually, from magnitude 1, they are already difficult to find. But so that you
know exactly in which region of the sky you should look for it, just remember that T CrB is located
in the constellation Corona Borealis, just below the corona, on the left side of the star Alphecca.
On a typical night, you can observe Corona Borealis as a
small semicircular arc right in the middle of Bootes and Hercules's constellations.
This is where the T CrB burst will appear as a "new" bright star going from a magnitude of +10 to
a magnitude of +2. So it will have a brightness similar to that of the North Star, Polaris.
Once its brightness peaks, it should be visible to the naked eye for several days before
dimming again, possibly for another 80 years. Finally, it would be best if you did not forget
that this star is located approximately 3000 light years from Earth. In reality,
the light we see from this star is the one that came out of it 3000 years ago,
and we will not know everything that is happening in that star right now until the year 5024.
That is, the nova that we will observe this year already happened 3000 years ago, but the
light of that event will only arrive this year. Now we want your opinion. On what date this year
do you think the T CrB Nova will occur? Write your prediction in the comments!