An exoplanet somewhat larger than Earth has recently been discovered and could be entirely covered in liquid water , one of the so-called ocean planets . This exoplanet has been discovered orbiting around one of the stars of a binary system located about 100 light years from Earth and it is believed that it could have many similarities with some moons of the solar system , such as Ganymede (Jupiter) or Enceladus (Saturn) , which would also be entirely covered by a layer of water, frozen in its case.
The exoplanet, named TOI-1452b , has been discovered by an international team of researchers from the Université du Montréal , in Canada, led by predoctoral researcher Charles Cadieux . The planet, which has a radius 70% greater than Earth’s and a mass almost 5 times greater , would be what is known as a super-Earth, a type of rocky planet larger than our planet but with similar characteristics. This super-Earth orbits TOI-1452, a star that is part of a binary system . Both stars are similar in size, with a radius a quarter that of the Sun , and orbit each other quite closely, about 100 astronomical units apart. This would be 100 times the distance from the Earth to the Sun (that’s the definition of an astronomical unit actually) or about two and a half times the distance from Pluto to our star.
Even though TOI-1452b orbits its star only 6% of the distance that separates Earth from the Sun, the smaller size of its star means that the temperature on the planet’s surface is similar to that of our own. , thus allowing the presence of liquid water.
This discovery has been made from a tip from NASA’s TESS space telescope , which routinely surveys the entire sky for exoplanet candidates. While observing the binary system of TOI-1452, he detected a slight variation in its brightness , which seemed to suggest the presence of a planet orbiting one of the two stars. However, TESS itself did not have enough resolution to distinguish the two stars , much less confirm which one this possible planet orbited around. It was here that the Montreal team came in and their observations from the Observatoire du Mont-Mégantic (OMM) , which were key to distinguishing that the planet orbited around TOI-1452 and that it was 70% larger than our own planet. , taking 11 days to complete each orbit.
This team spends part of its time checking TESS notices . On many occasions they turn out to be nothing more than false alarms, but on this occasion, after hard calibration work, extremely sensitive observations and a thorough analysis of the data obtained , it was confirmed that it was indeed an exoplanet . His discovery was later corroborated by an independent Japanese team. To estimate the mass of the discovered exoplanet they had to use another telescope, located in Hawaii and with the SPIRou instrument they observed the newly discovered planetary system for about 50 hours . This instrument is especially useful for studying small stars like TOI-1452, as it is capable of observing in the near infrared , the part of the electromagnetic spectrum in which the brightness of these dwarf stars is most intense.
The discovered planet is too small and too massive to be a gaseous planet , but its density, less than Earth’s, indicates that it must have a higher content of lighter compounds than the rocks and metals that account for 99% of the mass of Earth. the Earth . Because although our planet is 70% covered by water on its surface, the reality is that this compound is not very abundant and only accounts for 1% of the total mass of the planet . Other bodies in the solar system , such as several gas giant moons and even trans-Neptunian objects like Pluto, contain much higher proportions of water . However, these objects orbit too far from the Sun for all that water to be in a liquid state and therefore have icy surfaces.
TOI-1452b, on the other hand, fulfills both conditions: it has a density compatible with a large percentage of water in its composition, up to 30% according to the first observations, and it orbits close enough to its star so that all that water, especially that of the surface, survive in a liquid state. This is in fact one of the most promising candidates for ocean planet status that we know of to date. Still, we will have to wait for detailed studies of its atmosphere to confirm this. A study like this is precisely the strength of the James Webb Space Telescope . Due to the proximity and size of the planet, it would be an ideal candidate to point the telescope in its direction and try to determine what gases make up its atmosphere . That is why the team hopes to be able to reserve observation time in the space telescope in the future to check if their hypotheses were correct.
References:
Charles Cadieux et al, 2022, TOI-1452 b: SPIRou and TESS Reveal a Super-Earth in a Temperate Orbit Transiting an M4 Dwarf. The Astronomical Journal, DOI: 10.3847/1538-3881/ac7cea
