Discovery of a new class of exoplanets that could host life

Discovery of a new class of exoplanets that could host life

Discovery of a new class of exoplanets that could host life

A new class of exoplanets made up of half rock and half water has just been identified around the red dwarfs. According to the researchers, such a discovery could have major implications in the search for extraterrestrial life. Details of the study are published in the journal Science.

Red dwarfs make up over 70% of the universe’s stellar population. These objects, smaller and colder than the Sun, are known to host exoplanets. The fact that these stars are so common has naturally led astronomers to wonder if they could allow life as we know it to arise and develop.

This question is still debated for several reasons. On the one hand, these stars are known to be particularly unstable and release regularly large eruptions in their immediate environment. It is therefore likely that these eruptions “steal” the atmospheres and, by extension, the life of planets located a little too close.

If it is not yet known whether the worlds orbiting these red dwarfs are potentially habitable, it is also because of the lack of understanding researchers on their composition. To find out more, researchers recently focused on small worlds evolving around nearby red dwarfs (brighter, therefore easier to study). To do this, they looked at the data from the TESS satellite.

You are “new” worlds

Stars are naturally brighter than their planets. From our point of view, these worlds are therefore flooded with light, and therefore invisible. Astronomers can, however, learn more through indirect methods. The shadow created by a planet passing in front of its star is an example of this. Another is the slight gravitational influence of these planets on the motion of their star.

These data are essential. By capturing a planet’s shadow on its star, scientists can truly estimate its diameter. By measuring the small gravitational pull a planet exerts on a star, they can then estimate its mass. A team led by Rafael Luque of the University of Chicago concentrated on this work thirty-four exoplanets whose diameter and mass were already known. These details helped the researchers do this estimate their densityand then to deduce theirs probable compositions.

Of the thirty-four planets analyzed, the researchers identified 21 rocky worlds and seven gas giants. The remaining six objects, on the other hand, represented a new type of exoplanets consisting of approx half rock and half waterboth in liquid form and in the form of ice.

exoplanets
Artist’s impression of a half rock, half water world orbiting a red dwarf star. Credits: Pilar Montañés

Homes for life?

The fact that these planets are very watery inevitably leads us to think about life. However, note that although these worlds are visibly rich in water, that doesn’t necessarily mean they are covered in oceans. For example, water only represents 0.02% of the earth’s massthis makes our planet an astrophysically arid world, even though three quarters of the surface is covered with water.

Conversely, although the aqueous planets discovered by the researchers are half composed of water, that doesn’t mean they have oceans on the surface. All this water could in fact mix with the rock.

Future observations may tell us whether these planets are also found around larger stars. The researchers could also use the capabilities of the James Webb Telescope (JWT) to probe the composition of their atmosphere, if any, to analyze how they store all that water. This work could in turn make it possible to estimate their habitability potential.

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