One of the largest super-Earths discovered 200 light years from the Milky Way

One of the largest known super-hot Earths

Among the exoplanets classified as super-Earths, TOI-1075b is one of the largest. In astronomy, the term “super” has nothing to do with a superpower associated with a planet. It is used to refer to a planet that consists of rocks and metals and is larger than Earth. The criteria for qualifying an exoplanet as a super-Earth varies according to scientific publications, but very often a super-Earth can have a mass between 5 times and 10 times the mass of Earth and a radius between 1.5 and 2.5 times that of our blue Planet.

It also seems important to understand that the use of the compound word “super-Earth” absolutely does not mean that it is a planet that can accommodate any form of life, which is impossible for YOU anyway. -1075b which is a hot super-Earth. It actually orbits at a very close distance from its star, TOI1075, an orange dwarf. The temperature on the planet’s surface is over 1000°C. Such temperatures are sufficient to melt silicate rock and turn the planet’s surface into a sea of ​​molten lava.

The TOI-1075b super-Earth was discovered thanks to data sent by NASA’s Transiting Exoplanet Survey Satellite telescope. Better known by the acronym TESS, this small 350 kg space telescope is used to detect and count exoplanets. The principle of detection is based on the transit method.

Also read: The most distant super-Earth ever discovered is 25,000 light years away!

One of the few super-Earths located within the Fulton Gap

The TESS telescope, which specializes in detecting super-Earths. Credit: Alejo Miranda/Shutterstock

The transit method is one of the most used to detect exoplanets. It is actually a photometric technique based on the variation in the brightness of a star when a planet passes in front of it. This technique is often used in conjunction with the radial velocity method to find the mass and density of the detected planet.

The super-Earth TOI-1075b discovered by these methods has a radius 1.8 times that of Earth and is at a distance of 0.01159 astronomical units from its star, which represents approximately 1,730,000 kilometers. This very short distance explains its surface temperature of more than 1000°C. The orbital period of this hot exoplanet, that is, the time it takes to make a complete orbit around its star, is 14.5 hours. Finally, the mass of TOI-1075b, calculated using measurements of radial velocities, gives a very accurate 9.95 times the mass of Earth. As a super-Earth, this exoplanet is very impressive indeed.

Astronomers were surprised to discover that this hot super-Earth is located in the Fulton Gap. Also called the Fulton gap or Fulton gap, this hole describes a hollow that appears in the curve where the exoplanets are classified according to the size of their relative radii compared to Earth’s according to the number discovered until today. There is a “gap” located at radius magnitudes between 1.5 and 2.0 Earth radii, in which there are very few exoplanets.

Also read: GJ 3512 b, the planet that shouldn’t exist

A loss of mass due to atmospheric evaporation

To explain that TOI-1075b is located in the Fulton gap, astronomers think of the phenomenon of evaporation of the planet’s atmosphere due to its proximity to its star. This phenomenon of photoevaporation, which could concern exoplanets with relatively low masses, would therefore lead to a loss of mass.

Very often, exoplanets that fall into the category of super-Earths of a size close to TOI-1075b have a dense and thick atmosphere consisting of hydrogen and helium. However, due to a very high density estimated at twice that of Earth and its proximity to its star, this super-Earth is unlikely to have this type of atmosphere.

Currently, astronomers do not know the composition of this atmosphere, which evaporates due to its proximity to its star. First of all, TOI-1075b could have no atmosphere and be a completely bare rocky planet. It could also have a faint atmosphere, the composition of which could depend on the permanent evaporation of the ocean of molten lava that could cover the planet.

Astronomers are now expecting much from the James Webb Space Telescope to shed light on the atmosphere of this amazing super-Earth.

Also read: James Webb reveals photochemical evidence in an exoplanet’s atmosphere for the first time


Zahra Essack, Avi Shporer, Jennifer A. Burt, Sara Seager, Saverio Cambioni, Zifan Lin, Karen A. Collins, Eric E. Mamajek et al., “TOI-1075 b: A Dense, Massive, Ultra-Short Period Hot Super -Earth across the radius gap”, arXivsubmitted October 26, 2022,

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