Discovered Unusual Exoplanet with features never seen!
Hi! This is a video about exoplanets.
I'm sure you heard about them before, but if you never did, check this video out:
The haunting for exoplanets is something delicate and complicated,
and astronomers are struggling to invent new efficient methods, or
improving technologies, in order to find planets similar to Earth.
In fact, for the moment, the equations tell us that our exoplanetary discoveries
are biased, in the sense that we can only find some type of planets,
with specific orbital and physical parameters. For example, it's easy to find planets
like Jupiter, or maybe planets distant from their host star.
Instead, it is not easy at all to spot exoplanets like Earth.
And this is not because they don't exist. It's all about our limits in technology and methods.
Today we want to tell you something about Toi-2257b.
It was discovered with the help of the TESS telescope, one of the most known exoplanets
hunter, and it has some special characteristics. For example, it is two times bigger than Earth in
size, and it has an eccentricity parameter of zero point five. This is a huge eccentricity.
If you don't know what that means, don't worry: we will talk about this later in this video.
After some years of struggling, in 2013 the Transiting Exoplanet Survey Satellite
(TESS) was selected as an astrophysics mission in the Explorers Program of NASA.
TESS has a long history, beginning as a small, privately funded mission in 2006.
It started with financial backing from private companies, including Google, the Kavli Foundation,
and donors at the Massachusetts Institute of Technology (MIT).
This all changed in 2008, when MIT proposed TESS as an official NASA astrophysics mission,
restructuring it as a Small Explorer (SMEX) Class Mission. After not being selected in
this competitive process for NASA resources, TESS proposed again in 2010 as a NASA Explorer (EX)
Class Mission. TESS is the first of this new classification of Explorer missions. In 2013,
TESS was successful in the proposal process and NASA began the development of the project.
Needless to say, the main objective for TESS is to look for new worlds.
But how does it work? What's the process?
Even though it is supposed to find exoplanets, the telescope scans and surveys the brightest
stars near the Sun. Why?
As the name suggests, TESS uses the transit method in order to find them.
When a planet passes in front of its star, if we are lucky (that means, if the orbital
parameters of the planet are suitable for our observations!), we can assist in an eclipse.
When it happens, the recorded intensity of the bright star suddenly drops, and it does
so proportionally to the mass of the object that is passing through our telescope and the star.
It is pretty the same thing that happens when the moon is between the Earth and the Sun,
but it is a really small effect compared to what we can observe during a solar eclipse.
There are of course some other methods to look for exoplanets,
but each method is different and each method can give us different information.
Using the transit method, TESS can infer the mass, size, density and orbit of a large cohort of
small planets, including a sample of rocky planets in the habitable zones of their host stars.
TESS will provide prime targets for further characterization by the James Webb Space
Telescope, as well as other large ground-based and space-based telescopes of the future.
While previous sky surveys with ground-based telescopes have mainly detected giant exoplanets
and the Kepler space telescope has mostly found planets around distant stars that are too faint
for characterisation, TESS is finding many small planets around the nearest stars in the sky.
So basically TESS is looking for the brightest stars hosting transiting exoplanets
because they are the most favourable targets for detailed investigations.
So, up to now, TESS has discovered more than 2000 new candidate exoplanets.
Among others, it discovered an interesting planet orbiting around a small star.
The system is 188 light-years away from us, and it is very different from every
planet we have in our solar system. It is different from Jupiter and has
nothing to do with Earth. Maybe it has something in common with Pluto? The answer seems to be: no.
Its name is Toi-2557b. I know what you're thinking: what a weird name.
It stands for Tess Object of interest-2557 b. The number, 2557, and the letter,b, give us
the position in the sky map covered by the TESS telescope and some chronological information.
For example, if we'll ever find another planet in that stellar system, it will be called Toi-2557c.
Let's see what we know about this planet, and what we can expect to understand in the future.
For example, how big is it? What's his mass?
First of all, Toi-2557 b was recently confirmed as a planet, so it is no more a candidate.
Its radius is about 2 times the Earth radius, and its mass is about 5 times that of the Earth.
Can you figure it out? It is a pretty big and massive planet.
When it comes to exoplanets, however, the host star plays a huge role.
For example, a planet could orbit a neutron star or a type M star,
and everything would be different. Also, imagine moving the planet Earth
closer and closer to the Sun. At a certain point, we will have hard
times living on this planet, since solar radiation may hit us daily, and probably
that might not be the best thing in the world.
Now, talking about Toi-2557 b, it is really close to its host star, its semi-major axis being 0.145
astronomical units. This basically means that the planet is ten times
closer to its host star than we are to the Sun. Luckily, the host star, Toi-2557, is an M star. M
stars are among the coldest stars in the universe, and therefore it's okay for the planet to be that
close. In particular, the effective temperature of the star, that is, the photosphere temperature,
is about 3420.0 kelvin, a very low one. The star is really small compared to our Sun,
with a mass of about 0.33 solar masses and a radius of about 0.311 solar radii.
This star has an estimated age of about 8 billion years,
and therefore it is way older than our Sun.
This planet had twice the age of the Earth to develop and change.
Imagine how many things could have happened on that planet during this huge amount of time:
8 billion years. Maybe it was hosting life for a while, maybe not. It depends on some factors,
for example: what can we expect from the atmosphere? Are there oceans on this planet?
Or maybe it lost them by means of thermal mechanisms and other processes involving,
for example, stellar winds? For the moment, we don't know.
The orbit of Toi-2557 b is a really interesting one, mainly for 2 reasons.
First of all, whenever we detected such planets before, we found that their orbital period was
very short, something like 3 or 4 days maybe. This was of course implying a smaller
orbit around the host star. Instead, the orbital period
of Toi-2557 b is about 35 days, which is a tenth of Earth's orbital period.
Basically, you would have a birthday...per month! And also seasons would be very rapidly changing.
As we've already said, we don't know yet if it owns an atmosphere,
or if the planet lost it over time, but we could study it in the future in order to infer some
important information, for example, about oceans. In particular, we know that if there was an ocean,
some chemical molecules like ammonia will be trapped and dissolved in the ocean itself,
so we would expect a small quantity of ammonia in the atmosphere.
The other interesting thing about its orbit is, its eccentricity,
as we were outlining in the intro.
Toi-2557 b eccentricity is really pronounced.
Its value is 0.5. What does this mean?
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In mathematics, the eccentricity of a conic section is a non-negative
real number that uniquely characterizes its shape.
More formally two conic sections are similar if and only if they have the same eccentricity.
One can think of the eccentricity as a measure of how much a conic section
deviates from being circular. In particular: The eccentricity of a circle is zero.
The eccentricity of an ellipse which is not a circle is greater than zero but less than 1.
Planets and dwarf planets in the solar system have very small eccentricities,
with one notable exception: Pluto. Take a look at this picture.
You can clearly notice how Pluto's orbit differs from the other planet's orbits.
In fact, it has an eccentricity of about 0.25. Now, given that Toi-2557b has e=0.5,
try to imagine how elongated and squeezed and stretched its orbit has to be.
It is crazy, isn't it? Why did this happen?
This is something that astrophysicists should investigate more.
Maybe, at some point in the past, the exoplanet underwent a major
collision with an unknown object. This event may have changed its orbit
from a more regular one to the crazy and unusual orbit we observe today.
Or maybe there was some sort of planetary migration mechanisms going on,
and the opposite happened: the planet could have formed far away from the star, and then
migrated closer and closer.
This is something that we have to understand better.
The good news is that in December 2021, James Webb Telescope will be launched.
JWST will, of course, take a closer and better look at exoplanets suggested by the TESS mission,
and will eventually provide us with new detailed pieces of information about them.
Who knows, hopefully in the future we will be able to see that planet as a cute faint spot in
the sky, and we will therefore be able to study its atmosphere and its chemical composition.
Maybe in some years, we will be talking about the existence of new forms of life living in an
environment that is 2 times bigger than the Earth and 5 times more massive than our host planet.
Or maybe we will sadly understand that that's not the case,
and Toi-2557 b is a dead planet, with no atmosphere and no chance for life.
As you can see, science is not just about mind-blowing discoveries.
One should think about it as a big puzzle that everyone can contribute to finishing.
But it's also a special puzzle because it is a never-ending one:
every time you find a piece, the puzzle expands. Science is not about completing the puzzle. It
is about finding pieces and excluding others, and every piece is important.
TESS was just one of those pieces. JWST will be another one.
And this puzzle represents the most accurate picture of what we are:
the picture of our universe.
"This video ends here! Thanks for watching everyone! What do you think
about Toi-2557 b and what's your favourite exoplanet? Let us know in the comments below!
See you next time for another amazing video.”