US, WASHINGTON (ORDO NEWS) — Scientists suggest the existence of a huge number of terrestrial planets in our galaxy, but it is very difficult to find them. Today, only about a third of the more than 4,000 discovered and confirmed exoplanets are rocky, and most of them are within a few thousand light-years from Earth.
However, the recently discovered rocky exoplanet is located at a distance of 24,722.65 light years from us, which makes it the farthest known exoplanet of the Milky Way.
It is noteworthy that the exoplanet was discovered not by the common transit method, when the planet passes between the star and the observer, which is reflected in the brightness of the star, but by the method of gravitational microlensing. This method is based on predictions of the general theory of relativity.
Imagine two stars that are one after the other for an outside observer – from us. Gravitational microlensing occurs when the gravitational field of a closer star increases light from a distant star, acting like a lens. If the star closest to us has a planet, then the planet’s own gravitational field can make a significant contribution to the lensing effect.
This method is the most productive for finding planets located between the Earth and the center of the galaxy, since there are a large number of background stars in the galactic center.
“To have an idea of the rarity of such a discovery, the time required to observe the magnification associated with the host star was approximately five days, while the planet was discovered only during a slight five-hour distortion,” – Antonio Herrera Martin, Canterbury astronomer University of New Zealand.
After scientists found that the distortion was caused by a really different body than the star, and was not an instrumental error, the researchers began to obtain the characteristics of the star-planet system, designated OGLE-2018-BLG-0677.
The researchers found that the exoplanet found is a super-earth with a mass of 3.96 times the size of our planet. This makes it one of the planets with the smallest mass ever discovered by gravitational microlensing. The star around which the exoplanet revolves has a mass of only 0.12 solar. Scientists have not yet been able to determine whether it is a star with a small mass or a brown dwarf.
The distance between the planet and the star is from 0.63 to 0.72 astronomical units. Exoplanet makes a complete revolution around the luminary in 617 Earth days.
In order to determine the potential habitability of an exoplanet, scientists need to know the temperature of the star and the level of its activity, but this object is so far and so small that even modern devices cannot conduct its spectral analysis.
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