This Crazy “Forbidden Planet” shouldn’t be there!
From strange shapes to scorching hot temperatures, exoplanets are some of the craziest planets
out there. These alien worlds often push the limits of our imagination, taking us on a
wild ride through the universe. With over 4,000 exoplanets discovered so far, scientists
have encountered some truly weird and wacky specimens. It's like they say, the universe
is full of surprises, and these planets are no exception. Indeed, astronomers have recently
found an unusually large planet orbiting a small star, located about 280 light-years
from Earth. This planet seems to be the rebel of the planetary world and breaks the rules
we thought we knew. That’s why they called it “the Forbidden Planet”. So, buckle
up and get ready to encounter one of the universe's most bizarre exoplanets, as we explore the
vast expanse
of the cosmos. ---
The Forbidden Planet
Scientists have just discovered a new exoplanet, TOI 5205b, that is about the size of Jupiter,
making it a "forbidden planet”, because it orbits an M-dwarf star. I know what you’re
wondering: what’s the problem with that? Right? Don’t worry, I’ll get there in
a minute. This giant exoplanet was spotted by the
Transiting Exoplanet Survey Satellite (TESS) launched by NASA in 2018. TESS is a precious
piece of engineering: it surveys the light of the brightest and nearest stars to spot
dips in the starlight, indicating that the star has planets orbiting around it. This
planet orbits an M-dwarf star called TOI-5205, which is about 40% the size and mass of our
sun, and is much cooler than the sun: it is therefore a tiny cute little star.
And it is exactly the small size of this star that usually doesn’t allow giant planets
to be found in orbit around it. M-dwarf stars, like TOI-5205, usually don't
have much material in their circumstellar disk when they are formed, which makes it
difficult for such stars to host giant planets like the one found by TESS, When scientists
discovered this planet, they couldn’t believe it: TOI 5205b, with its huge mass, challenges
the current understanding of the formation mechanism of most exoplanetary systems. However,
the universe is full of surprises, and the TESS mission has found thousands of potential
planets like TOI 5205b, apparently breaking the laws of physics.
Shubham Kanodia, a postdoctoral fellow at the Carnegie Institution for Science in Washington,
DC, was surprised by the new discovery. "The host star, TOI-5205, is just about four times
the size of Jupiter, yet it has somehow managed to form a Jupiter-sized planet, which is quite
surprising," he said. To give you a better perspective, allows me
to compare the planet to a pea orbiting around a lemon, while in our solar system, Jupiter
could be compared to a pea around a grapefruit, representing our sun. Can you understand the
difference?
Of course, the detection and discovery of this exoplanet are really exciting for scientists
which concern with the development of new planet formation theories. However, TOI-5205b
is not interesting in terms of habitability. This exoplanet is not habitable, as it is
much too close to its star and its atmosphere contains hot gas. Any living organisms would
burn, coming to a bad end. ---
Breaking the law
But let's get to understand better the mechanisms of planetary formation, to see why this Jupiter-sized
planet isn't supposed to be there. Ever heard of a pancake-shaped disk of gas
and dust floating around a star? That's called a circumstellar disk, and it's where all the
magic happens when it comes to planet formation. It's like the playground for baby planets
- they start off as tiny dust grains and grow up to be big and beautiful planets. But how
do these disks form in the first place? Well, it's all thanks to the laws of gravity.
When a giant cloud of gas and dust collapses due to gravity, it starts to spin. This spinning
motion eventually causes a flat disk to form around a central protostar, kind of like how
dough flattens out when you spin it on a pizza tray (except this is happening in space, and
without the delicious toppings). The disk is made up of gas, dust, and tiny
rocky particles that come together to form what we call planetesimals. These planetesimals
can then stick together and grow into larger bodies, eventually becoming the planets we
know and love. But not all circumstellar disks are created
equal. Depending on the type of star they orbit, they can look different and host different
types of planets. For example, disks around massive stars tend to be hotter and more turbulent,
making it harder for planets to form. Disks around smaller, cooler stars like our sun
are more stable and have a greater chance of producing habitable planets.
The journey from a tiny dust grain to a full-fledged planet is a long one, taking millions of years.
But the process can be broken down into a few key stages. First, dust grains collide
and stick together to form planetesimals. These planetesimals then grow by accreting
more material from the disk, eventually becoming planetary embryos. Finally, these embryos
collide and merge to form planets. It's important to note that this model of
planetary formation is the best we have so far, but it's not perfect. There are still
many unanswered questions and mysteries surrounding planet formation, and scientists are working
hard to uncover the secrets of our cosmic origins. Maybe TOI-5205b could represent one
of the puzzle’s missing pieces! ---
Criminal Migrating Planets
One of the ways that material is dissipated is through decreasing dust opacity due to
grain growth. This process occurs throughout the lifetime of a star and results in the
formation of mid-disc dust lanes. Another mechanism is photoevaporation, whereby material
is blown away by X-ray or UV photons from the star's stellar wind.
Just to understand what a circumstellar disk looks like, observe this picture taken by
the ALMA telescope: It shows the protoplanetary disc surrounding
the young star HL Tauri. These new ALMA observations reveal substructures within the disc that
have never been seen before! And most importantly, these structures can tell us something about
the presence or lack of planets around this star! How? Well, it’s quite easy.
The planets are able to carve gaps in the circumstellar disk through a process called
gravitational perturbation. As the planets move through the disk, they exert a gravitational
force on the surrounding matter, causing it to accumulate in certain areas and creating
gaps in others. This process has been observed in many protoplanetary disks, including the
one surrounding the young star HL Tauri imaged by ALMA. By studying the substructures within
the disk, scientists can gain insight into the number and size of planets present in
the system, as well as their orbits and masses. This information is crucial for understanding
the formation and evolution of planetary systems across the universe.
Anyway, we were addressing the dissipation of matter in the circumstellar disk. The most
significant dissipation occurs in the inner part of the disc, where the material is blown
away in the first million years since the star's formation. This region is closest to
the star and hence the hottest, leading to the creation of a hole in the middle of the
disk, as scientists could observe again using ALMA: take a look at these pictures! They’re
quite impressive. As a result, we do not expect to find gas
giants so close to a star because these planets would have been blown away by a hot dust circle.
Moreover, if the star is an M-dwarf star, the available material is not sufficient at
all to form such gas giants. All of this, presents a challenge when explaining
the observed presence of gas giants around some stars, just like what happens with TOI-5205b.
Scientists have been trying to explain this weird behavior. One solution could be planetary
migration, whereby a giant planet forms outside the inner part of the disc and then migrates
inwards toward the star. This process can explain the presence of hot Jupiters, which
are gas giants found very close to their host star.
Actually, migration is thought to be one of the main mechanisms for the formation of Jupiter-like
planets. They are usually found really close to their host stars, leading to think that
they must have been formed somewhere far away, in the outskirts of the circumstellar disk,
and sank towards the center as time passed by.
So..do you think our Forbidden Planet could have undergone a migration process in the
past? Let me know in the comments below! ---
Future Studies: JWST
Researchers want to observe the planet in the future using the James Webb Space Telescope,
which could detect if TOI-5205b has an atmosphere and unlock more of the secrets about how it
formed. James Webb is basically going to be the superhero
of telescopes, with its incredible ability to observe the universe in ways we’ve never
imagined before. Its mission is to study the universe from the first galaxies formed after
the Big Bang to the formation of stars, galaxies, and planets. And, of course, it’s perfect
for studying the atmospheres of exoplanets like TOI-5205b.
The James Webb Space Telescope is like the ultimate exoplanet detective. It has the ability
to detect the composition of exoplanet atmospheres, even those that are very far away. This is
done by observing the light that passes through the atmosphere of the exoplanet as it transits
in front of its star. This way, we can determine what gases are present in the atmosphere,
such as oxygen, methane, and water vapor, which are all important biomarkers for life.
But wait, there’s more! The James Webb Space Telescope can also measure temperature variations
on exoplanets, which can indicate the presence of weather patterns, such as clouds or storms.
This is especially important in the search for habitable exoplanets, as stable weather
is necessary for the development and sustainability of life.
Plus, the James Webb Space Telescope can also observe the light reflected off exoplanets,
which can give us information on their surface features and even their color. Who knows,
maybe one day we can admire a beautiful blue or green exoplanet from afar!
All in all, the James Webb Space Telescope is definitely the ideal tool for studying
exoplanet atmospheres and searching for signs of life. So, let’s hope TOI-5205b has some
interesting secrets to reveal to us! ---
Hey! This video ends here! Thanks for watching everyone! What are your thoughts about the
Forbidden Exoplanet? Are you excited to know more about it? Stay tuned for more updates!