An exoplanet covered in volcanoes has been discovered, could it harbor life?

EXOPLANET. Similar in size to Earth, an exoplanet has been discovered by space telescopes in the constellation Cup. The star is covered with active volcanoes and could have an atmosphere.

[Mis à jour le 26 mai 2023 à 11h23] The Spitzer and TESS space telescopes have discovered a new exoplanet located in the constellation of the Cup about 90 light-years from Earth. Placed in orbit around a red dwarf star, the star has two neighbors discovered in 2019. Thus, a mini Neptune and a super-Earth evolve alongside it. The first measures two and a half times the diameter of the Earth while the second is barely larger than our planet. This time, an Earth-sized star was discovered in this system, nestled between the other two. But this planet has the particularity of hosting intense volcanic activity.

Although exoplanet LP 791-18 d is similar to Earth in size and mass, the comparison ends there. First, this celestial body is much closer to its star than we are to the Sun. Moreover, it goes around it in just 2.8 days. According to the researchers, it is this proximity that causes very significant volcanic activity on the planet. Moreover, because of this short distance with its star and the force of attraction of the latter, the planet constantly presents the same face to its star while the other side remains immersed in darkness.

In May 2023, a group of researchers discovered an exoplanet evolving in a distant star system 90 light years from Earth. The star, named LP 791-18 d, is the site of very intense volcanic activity which is reminiscent of that of Io, one of the main moons of the giant Jupiter.

This new exoplanet has the particularity of following an elliptical orbit, which means that it passes alternately very close then very far from its star as it goes around it. This phenomenon is due to the fact that the two other nearby planets exert on it forces of attraction which deform its orbit.

The consequence of this elliptical trajectory is that the exoplanet undergoes what are called tidal forces caused by its movement and by the attraction of its star. In other words, as the planet moves in its orbit, it is subjected to different forces that deform it and cause it to heat up. This thermal energy is released in the form of intense volcanism that could sustain an atmosphere around the planet.

What is the definition of an exoplanet?

An exoplanet is a planet located outside the solar system. It moves in orbit around stars other than the Sun. Exoplanets present a great diversity: telluric planets, composed of rocks, gaseous planetsor even ice giants, they are given nicknames such as “super Earth”, “hot Neptune” or even “hot Jupiter” according to their characteristics and their similarities with the planets of our solar system.

What is the first exoplanet discovered?

The first exoplanet orbiting a star was discovered in 1995 and is named 51 Pegasi b. It is 50.9 light years from Earth in the constellation Pegasus. This planet orbits the star 51 Pegasi. A yellow dwarf slightly older than the Sun, this star is also a little more massive and larger than it.

51 Pegasi b is located so close to its star that it circles it in just 4 days. However, it is a gas giant, like Jupiter or Saturn for example. It is for this reason that it is called “Hot Jupiter”.

What did James Webb discover about exoplanet WASP-96b?

Our knowledge of exoplanets could be greatly improved in the near future thanks to the James Webb Space Telescope. Indeed, one of its main missions is to study the composition of exoplanets and in particular that of their atmosphere. James Webb’s mission is to probe the atmospheres of distant planets using a particularly ingenious system. The telescope waits for the exoplanet to pass in front of the star around which it is rotating to analyze its light. When light from the star passes through the planet’s atmosphere, it acts as a filter and blocks some of the light. The telescope can then deduce the composition of the atmosphere surrounding the planet and therefore the conditions prevailing on the surface of the latter. On the program, “hot Jupiters”, gaseous planets evolving close to their star, but also telluric planets more similar to Earth.

Its first target is WASP-96b, a gas giant located 1,150 light-years from Earth. When the first images from the space telescope were released in July 2022, NASA also released the results of the first analyzes of light passing through WASP-96b’s atmosphere. The results are final, the latter contains water, traces of mist and clouds.

Which exoplanet is closest to Earth?

The closest planetary system to Earth is Alpha Centauri C. Its central star is Proxima Centauri and is 4.246 light-years from Earth, or 40 trillion kilometers. Today, several planets are known to revolve around this star.

The first, Proxima b, was discovered in August 2016 and was the subject of a Press release scientist from the European Southern Observatory as well as a publication in the journal Nature. A few years later, the planet Proxima c was detected, orbiting farther from the star Proxima Centauri than its neighbor Proxima b. Finally, in February 2022, Proxima d was discovered, bringing to three the number of planets that orbit Proxima Centauri.

The closest planet to Proxima Centauri would be the planet Proxima d which would thus go around the star in 5 days. Proxima b would be located in the star’s habitable zone, which means that it could harbor water in liquid form. Finally, Proxima c would be located much further from the star and would go around it in 5 years according to the magazine National Geographic.

What new exoplanet around Proxima Centauri?

After Proxima Centauri b and Proxima Centauri c, a third planet was discovered orbiting around Proxima Centauri. It was a team of astronomers from the University of Porto, in Portugal, who spotted the planet thanks to the variations in the speed of its star due to the force of gravity of the planet.

Called Proxima Centauri d, this exoplanet has a mass about a quarter of Earth’s and a size just over a quarter of Earth’s. It takes about 5 days to go around its star, because it is extremely close to it. According to astronomers, a priori, this position excludes it from the habitable zone of this star. This means that it is placed too close to its star for conditions to be conducive to the emergence of life on its surface.

What is special about exoplanet Kepler-452b?

Kepler-452 b is an exoplanet located 1,400 light-years from Earth in the constellation Cygnus. Its particularity is to be relatively similar to our planet Earth. Indeed, its radius measures 1.6 times that of the Earth. Their sizes are almost identical. It takes 384 days to go around its star, a duration comparable to that of the revolution of the Earth around the Sun which is 365 days. This planet is therefore in the habitable zone of its star and receives approximately the same amount of energy from its star as the Earth receives from the Sun. All these elements make it a planet very similar to ours but located in another planetary system, explains the magazine Science and Future.

The star around which it revolves, Kepler-452, is a slightly brighter star and a little larger than the Sun, but has the same temperature as the latter. The planetary system that contains the star and the exoplanet, however, is 1.5 billion years older than our planetary system. Thus, it could give us an idea of ​​what the Earth could become in the future.

What are the potentially habitable exoplanets?

According to a NASA press release published in October 2020, there are 300 million potentially habitable planets in our galaxy. To arrive at this figure, the researchers evaluated the number of stars likely to be accompanied by a rocky planet where water could exist in a liquid state in a sustainable way. The work of the James Webb telescope could help us to clarify this question and identify candidate planets for this category.

Some exoplanets are true aquatic worlds. This is the case of TOI-1452 b, a planet located in the constellation of the Dragon discovered by a Canadian team in August 2022. The planet would be entirely covered by an ocean deeper than those we know on Earth. The James Webb Space Telescope could tell us a little more about this planet during its mission.

More recently, in December 2022, NASA announced that it had discovered, thanks to the Spitzer and Hubble telescopes, that two planets orbiting the star Kepler-138 are also part of these aquatic worlds. Located in the constellation of Lyra, these planets, named Kepler-138c and Kepler-138d, are located much closer to their star than we are to the Sun. Their atmospheres would be particularly hot and humid and the oceans that cover them would be composed of water at high pressure.

In addition to these two planets, telescopes have revealed signs of the presence of a third planet, called Kepler-138e. The latter is very promising since it would be located in the star’s habitable zone and could therefore accommodate liquid water. It would therefore be more likely than others to see life appear in its oceans.