Bulletin: The telescope dedicated to the search for exoplanets reveals the presence of eight super-Earths! A possible indication of life has been spotted!
Super-Earths represent exoplanets that surpass our planet in terms of mass and size, while remaining smaller than gas giants such as Jupiter and Saturn. The question remains: could a super-Earth be the long-awaited Earth 2.0?
The search for Earth 2.0 remains one of the major challenges in astronomy. This term designates an exoplanet with notable similarities to our own planet, both in terms of composition, atmosphere and size. However, the search for planets smaller than the gas giants, such as Jupiter and Saturn, is more complex.
This partly explains why frequently discovered exoplanets are often gas giants. Earth-sized planets, or even smaller ones like Mars, are identified less frequently, mainly because current detection techniques are more effective for larger objects.
The TESS space telescope, dedicated to the search for exoplanets, recently identified eight super-Earths. What is of interest is that of these, six are considered "key planets" that could potentially explain the absence of planets of intermediate size between Earth and Neptune.
Exoplanets
Celestial bodies located outside the solar system are classified as exoplanets, whether they orbit stars or are isolated. Recently, a study even put forward the term "blanete" to describe exoplanets orbiting black holes.
The major interest of researchers lies in the possibility of spotting an exoplanet sharing similarities with Earth, which could indicate an environment suitable for life. This is why the quest for what we call “Earth 2.0” currently represents the primary objective of astronomy.
The big question in astronomy
At the end of each decade, astronomers from around the world come together to decide what the big question of the following decade will be. Between 2019 and 2021, many articles were published for this purpose, called Astro2020
The consensus among astronomers was that the focus of this decade would be on exoplanets and the search for Earth 2.0. The James Webb Space Telescope's own was launched with this goal, in addition to the study of the young universe. In 2019, the Nobel Prize in Physics was awarded to scientists who discovered an exoplanet for the first time.
How to find exoplanets?
Planets do not emit their own light like stars do. Finding them is a complicated mission. The most common method is exoplanet transient events.
A transient event occurs when an exoplanet passes in front of the star it orbits, causing the star's brightness to dim a bit for a short period of time.
By calculating the time during which the star's brightness decreases and the frequency with which this happens, it is possible to find exoplanets. The downside is that other bodies can cause the same effect, such as other stars or even the star itself varying in brightness.
TESS
TESS is a space telescope that was launched as a successor to Kepler. The idea of TESS is to study these transient events and to be able to identify exoplanets in stars close to the Sun, that is to say in a nearby region.
TESS has already found 400 exoplanets that have been confirmed and more than 6,000 await confirmation. Confirmation comes through more observations or statistical methods which may even include the use of machine learning.
Why don't we find "average" planets?
In the study of exoplanets, there is a problem linked to their population. Because it is through transients, larger planets like Jupiter and Saturn are more easily found. Despite this, planets the size of Earth and even smaller have also been discovered.
But there is a mass range where planets of this type are rarely found: between 1.5 times the mass of Earth and twice that mass.
The question remains: why are these planets not found? And if they don't form with the same frequency, why? This is why the exoplanets between these masses are called "key planets"
6 planets are key
TESS has identified eight super-Earths, which are exoplanets with masses greater than that of Earth up to that of Neptune. Six of these objects fall into the range considered key planets and could help us explain their rarity in observations.
One explanation is that key planets can lose their atmospheres through certain processes, and the 6 key planets found by TESS could help us answer this question. Simulations of these planets were carried out and one of them revealed something never before seen.
The planet with methane
To understand the atmosphere of these planets and their composition, the researchers who led the work carried out simulations. One of these simulations showed that one of them could present a quantity of methane gas which is a bio-signature.
It is still too early to confirm the real presence of methane on any of them. The group says the James Webb Telescope would be key to confirming or not the presence of this gas in the exoplanet's atmosphere.
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