Two supermercuries found around the same star. Before that, they were found only seven times in space.

While observing the star system HD 23472 using the ESPRESSO spectrograph, scientists have found three super-Earths

and two supermercuries. The last of the two types of exoplanets is very rare. So far, only eight have been found.

A photograph of the planet Mercury taken by NASA's MESSENGER Wide Field Camera (WAC).
Credit: NASA/Johns Hopkins Applied Physics Laboratory/Carnegie Institution of Washington.

The purpose of the study published in the journalAstronomy & Astrophysics, was to characterize the composition of minor planets and understand how it changes depending on the position of the planet, temperature and properties of stars. It turned out that the system consists of three super-Earths with its own atmosphere and, surprisingly, two supermercuries.

The density of known rocky planets as a function of the estimated mass fraction of iron in the silicate of the protoplanetary disk.
The black solid line shows the correlation forknown exoplanets (blue dots), excluding potential supermercuries (brown dots). The black symbols represent the planets of our solar system - from top to bottom Mercury, Mars, Earth and Venus.
Photo: Barros et al., 2022

Of the five planets in the HD 23472 system, three have a masssmaller than the earth. These are among the lightest exoplanets, and their masses have been measured using the radial velocity method with ESPRESSO. The spectrograph was installed at ESO's Very Large Telescope (VLT) in Chile.

Radius versus mass plot of exoplanet HD 23472 (black dots) compared to other known exoplanets.
Earth (blue star) and Venus (yellow star) are shown for comparison.
Dashed lines represent mass-radius models for various planetary compositions.
Photo: Barros et al., 2022

The planet Mercury in the solar system is differentrelatively large core and relatively small mantle than other planets, but astronomers do not know why. Surprisingly, scientists have recently found other exoplanets with similar characteristics around other stars. They were called supermercuries.

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Cover photo: An artist's impression of a five-exoplanet system. Image Credit & Copyright: NASA/JPL-Caltech