Is Betelgeuse About to Explode?
Intro Nothing lasts forever.
While we Earthlings are familiar with the cycle of life, the concept is not just confined
to our planet.
It is a universal reality that everything must eventually come to an end, and all the
stars in the cosmos are no different.
While it is a rare occurrence for humanity to observe a stellar explosion, new reports
state that Betelgeuse may be edging towards impending doom.
Let's take a closer look.
Stellar Evolution The life cycle of a star is largely determined
by its overall mass.
The bigger a star is in size, the faster it burns and the shorter its life cycle is.
The mass of a star is determined by the amount of matter which is available in the nebula
it exists in.
All stars are formed in a giant cloud of dust and gas drifting in the endless void of space.
These clouds of debris are called nebulae.
Over time, chunks of this gas and debris are pulled together by gravity and collapse upon
themselves.
This causes the massive deposits of hydrogen gas contained in the nebula to be pulled together
and start spinning.
As this gas spins faster, it starts heating up and becomes what is known as a protostar.
This is how stars as we know them first come into existence and start their journey through
life which lasts billions of years.
Our Sun, one of the biggest reasons for life on Earth went through the same process in
its infancy.
Currently, the Sun is classified as a main-sequence star and will continue to shine brightly for
millions to billions of years to come.
Whatever the size of a star may be, they all follow the same 7-stage cycle of life which
starts as a cloud of gas and ends as remnants of the once-mighty celestial body.
Every star that exists starts as a giant cloud of gas and debris.
This is the first stage of stellar evolution and marks the start of the life cycle of a
star.
The overall temperature in the cloud must be low enough to support the synthesis of
molecules.
The process of formation begins when a particularly dense region of this gas cloud begins to warm
up and shrink rapidly.
This is usually caused by one of several possible events that may take place in the vicinity
of the cloud.
These include things like galactic collisions or an incredibly powerful supernova explosion
which could send ruptured matter into the cloud at very high speeds.
Such an occurrence can initiate a gravitational collapse of the molecular cloud significant
enough to trigger the birth of a new star.
Each of these gas clouds can contain enough matter to form anywhere from a few dozen to
many thousands of stars.
To put things into perspective, our Sun is 864,400 miles across.
This means that it would require a collection of dust and gas which is about a hundred times
the size of our solar system to form.
The Orion cloud complex located in the Orion system is one example of a star that is in
this stage of its life cycle.
When the gas particles contained in the molecular cloud constantly collide with each other,
heat energy is produced.
As the temperature keeps rising due to this reaction, it results in the formation of a
warm clump of molecules called a protostar.
This is the 2nd stage of stellar evolution.
The creation of such protostars can be easily observed in the universe with the use of infrared
vision.
This is because these infant stars are much warmer than other materials contained in the
molecular cloud.
Depending on the size of a molecular cloud, it could support the creation of several such
stars at the same time.
This warm clump of molecules can be classified as a protostar for as long as other matter
keeps being pulled inside it.
For stars that are the same mass as our Sun, this phase of stellar evolution can last approximately
100,000 years.
After this, the protostar stops growing in mass, and the disk of debris that surrounds
it is destroyed by radiation.
If the protostar is unable to acquire sufficient mass, it will instead turn into a brown dwarf.
These are classified as substellar objects that can't sustain hydrogen fusion reactions
in their core due to a lack of mass.
A brown dwarf is an object that is too big to be called a planet, yet too small to classify
being a star.
These objects were only a theoretical concept until 1995, although today it is thought that
there is a brown dwarf for every six stars in the universe.
When matter eventually stops falling into the Protostar and a tremendous amount of energy
is released by the object, it signifies that the star has entered its 3rd phase of stellar
evolution and can now be classified as a T-Tauri star.
The overall temperature of a star in this stage of its life cycle is not high enough
to support nuclear fusion in its core.
This phase lasts for around 100 million years, and when it finally ends, the star is ready
to enter the most extended phase of its developmental journey.
The main sequence is the 4th and the longest phase of stellar evolution.
It is the phase our Sun currently sits in.
It starts when the core temperatures of the star finally get high enough for nuclear fusion
to commence.
During this process, the protons of hydrogen are converted into atoms of helium due to
an exothermic reaction.
This means it gives off more heat than required, allowing the core of a star in the main sequence
phase to release a tremendous amount of energy for most of its life.
As the star continues to convert hydrogen atoms into helium for most of its life, eventually
the hydrogen fuel contained on its surface runs out and the internal reaction which has
been taking place in its core for millions of years suddenly slows down and stops.
Without this reaction, the star starts to cool down and contract inwards through gravity
which causes it to expand.
As this expansion continues, the star first turns into a subgiant star, which eventually
leads to it becoming classified as a red giant.
This is the 5th stage of stellar evolution.
Since red giants have drastically cooler surfaces compared to main-sequence stars, they give
off a red appearance rather than the yellow we are so accustomed to thanks to our Sun.
As the star expands, it causes the helium molecules found in its core to fuse.
The energy released from this reaction prevents the core of the star from collapsing.
Once the fusion of helium molecules ends, the core shrinks and begins fusing carbon.
This process keeps repeating until iron appears in the core.
The fusion reaction thanks to the presence of iron then starts to absorb energy, causing
the core of the star to collapse.
This implosion is an event that transforms massive stars into a supernova and smaller
stars similar to the size of our Sun contract and turn into white dwarfs.
This is the 6th stage of the life cycle of a star.
In the final stage of its life cycle, the implosion of a star causes most of the debris
from its outer layers to blast away into space.
The core of the star, however, implodes and turns into either a neutron star or a singularity
known as a black hole.
Stars that are not too massive avoid this implosion, but instead their cores contract
into tiny hot stars known as white dwarfs.
Stars that are smaller than the Sun don’t have enough mass to burn brighter than a faint
red glow in the night sky.
While these stars are hard to spot, they are very common in the universe and can last for
trillions of years.
Did Betelgeuse Explode?
Analyzing data from NASA's Hubble Space Telescope and several other observatories, astronomers
have concluded that the bright red supergiant star Betelgeuse quite literally blew its top
in 2019, losing a substantial part of its visible surface and producing a gigantic Surface
Mass Ejection.
This is something never before seen in a normal star's behavior.
Our Sun routinely blows off parts of its tenuous outer atmosphere, the corona, in an event
known as a Coronal Mass Ejection.
But the Betelgeuse SME blasted off 400 billion times as much mass as a typical CME!
The monster star is still slowly recovering from this catastrophic upheaval.
These new observations yield clues as to how red stars lose mass late in their lives as
their nuclear fusion furnaces burn out, before exploding as supernovae.
The amount of mass loss significantly affects their fate.
However, Betelgeuse's surprisingly petulant behavior is not evidence that the star is
about to blow up anytime soon.
So, the mass loss event is not necessarily the signal of an imminent explosion.
Scientists are hard at work analyzing data from different sources to piece together the
puzzle of the star's petulant behavior before, after, and during the eruption.
This includes new spectroscopic and imaging data from the STELLA robotic observatory,
the Fred L. Whipple Observatory's Tillinghast Reflector Echelle Spectrograph, NASA's Solar
Terrestrial Relations Observatory spacecraft, NASA's Hubble Space Telescope, and the American
Association of Variable Star Observers.
Scientists state that they have never before seen a huge mass ejection of the surface of
a star.
We are witnessing something that we don't completely understand, it is like watching
stellar evolution in real-time.
The titanic outburst in 2019 was possibly caused by a convective plume, more than a
million miles across, bubbling up from deep inside the star.
It produced shocks and pulsations that blasted off the chunk of the photosphere leaving the
star with a large cool surface area under the dust cloud that was produced by the cooling
piece of the photosphere.
Betelgeuse is now struggling to recover from this injury.
Weighing roughly several times as much as our Moon, the fractured piece of photosphere
sped off into space and cooled to form a dust cloud that blocked light from the star as
seen by Earth observers.
The dimming, which began in late 2019 and lasted for a few months, was easily noticeable
even by backyard observers watching the star change brightness.
One of the brightest stars in the sky, Betelgeuse is easily found on the right shoulder of the
constellation Orion.
Even more fantastic, the supergiant's 400-day pulsation rate is now gone, perhaps at least
temporarily.
For almost 200 years astronomers have measured this rhythm as evident in changes in Betelgeuse's
brightness variations and surface motions.
Its disruption attests to the ferocity of the blowout.
The star's interior convection cells, which drive the regular pulsation may be sloshing
around like an imbalanced washing machine tub.
TRES and Hubble spectra imply that the outer layers may be back to normal, but the surface
is still bouncing like a plate of gelatin dessert as the photosphere rebuilds itself.
Though our Sun has coronal mass ejections that blow off small pieces of the outer atmosphere,
astronomers have never witnessed such a large amount of a star's visible surface get blasted
into space.
Therefore, surface mass ejections and coronal mass ejections may be different events.
Betelgeuse is now so huge that if it replaced the Sun at the center of our solar system,
its outer surface would extend past the orbit of Jupiter.
In the coming years, astronomers may use the James Webb Space Telescope to detect the ejected
material in infrared light as it continues moving away from the star.
Outro If you found this video informative, you may
also enjoy this one which talks about NASA’s new plan to colonize Venus.
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