A mysterious exoplanet just 138 light-years from Earth may be in the process of transformation. Analysis of the exoplanet HD-207496b, with a mass of 6.1 times that of Earth and a radius of 2.25 times, suggests that it has a gaseous atmosphere, a global ocean, or a mixture of both. shrinking to become a super-Earth.

This could help astronomers unravel the mystery of exoplanet detection, the gap between the masses of rocky planets larger than Earth and gaseous planets smaller than Neptune. But we will take a closer look at this mysterious exoplanet to characterize its atmosphere. It is a diverse galaxy with many very different exoplanets. At the time of this writing, astronomers have discovered and confirmed about 5,300 worlds outside the solar system, and there were nearly twice as many unconfirmed candidates.

With this information, scientists can perform statistical analysis to find trends in the evolution of planetary systems. And one interesting thing we learned is that exoplanets with 1.5 to 2 times the mass of the Earth and orbits shorter than about 100 days are in severe shortage.

This is known as the low radius valley of the planet. Underneath we often find rocky worlds such as Earth, Venus and Mars; we call them super worlds. Above it we find worlds with thick atmospheres like miniature Neptunes and we call them mini Neptunes. The cause of the valley isn’t entirely clear, but a growing body of evidence is starting to suggest that proximity to the parent star has something to do with it. Below a certain critical threshold, it is possible that the exoplanet does not have enough mass to maintain the gravitational pressure on its atmosphere (the gas evaporates by the radiation of the star).

We’ve discovered several worlds that hold clues to this process, and scientists are looking for more as the study continues, using the High Accuracy Radial Velocity Planet Searcher (HARPS) on the European Southern Observatory’s 3.6-metre telescope at La Silla Observatory in Chile. About candidates identified by NASA’s TESS exoplanet search space telescope.

TESS searches for exoplanets by looking at a patch of sky, its precision instruments tuned for very faint dips in starlight; this could be evidence that an orbiting exoplanet is passing or transiting between us and a star. If these transitions occur regularly, astronomers can easily detect the presence of an orbiting object and determine its period. If the star’s brightness is known, the depth of the slopes — how much starlight is blocked — allows astronomers to calculate the radius of the orbiting object.

HARPS reveals a different indicator. When an exoplanet orbits a star, it exerts its own gravitational pull. Technically, an exoplanet does not revolve around a star; instead, the two bodies revolve around a common center of mass known as the center of gravity. Because the stars are much larger than their own world, they don’t move much, instead they wobble in place every minute.

This is what HARPS can measure. As a star moves towards and away from us, the wavelength of its light changes, getting smaller as the star gets closer and longer as it moves away. How much the star moves depends on the mass of the exoplanet, so astronomers can calculate that too. Once you know the exoplanet’s mass and radius, you can add them together to calculate its density. This is where it gets really interesting, because depending on the density you can figure out what an exoplanet is made of.

When TESS detected an exoplanet with a radius 2.25 times that of Earth and a 6.44-day orbit with an orange dwarf star called HD-207496, they turned to HARPS for a closer look. HARPS data showed HD-207496b’s mass to be about 6.1 times the mass of Earth. This means that the density of the exoplanet is about 3.27 grams per cubic centimeter. This is a much lower density than Earth’s density of 5.51 grams per cubic centimeter, and means that HD-207496b’s composition is not entirely rocky. So the researchers ran simulations to see what the world is made of.