The discovery of a new planet orbiting the star closest to Earth
Astronomers have discovered a new planet called Proxima D, orbiting Proxima Centauri, known as "Centaur Proximal", the star closest to the solar system of the planet Earth.
A study published in the journal Astronomy & Astrophysics showed that Proxima D has a mass of only a quarter of the mass of Earth, and is one of the lightest in the group of about 5,000 exoplanets orbiting stars other than the Sun.
The star Proxima Centauri is located four light-years from our sun, and it is much smaller and twice as cool as it, and belongs to the class of stars called "red dwarfs". Before Proxima D, the planets Proxima B and C were discovered.
Although the star is close and not very large (which means that its radiation is not very dazzling), it is difficult to detect the planets in its bosom, because the Earth is not on the same level from the outer planet and its star, so it is not possible to apply the so-called “transit method”, which is to monitor Luminosity differences caused by a planet passing in front of its host star, such as a small eclipse.
Therefore, it was necessary to follow the radial velocity method, which is based on measuring the speed of the star, by observing whether it is approaching or moving away from us. And if planets revolve around it, this speed will be slightly different.
Thanks to this method, the Earth-like mass of Proxima and located in the "habitable" zone (neither too close nor too far from the star) and Proxima C, the smaller one, were discovered years ago.
Proxima D is located four million kilometers from its star, less than a tenth of Mercury's distance from the sun.
Baptiste Lavie of the Department of Astronomy at the University of Geneva and a member of the European Southern Observatory's Very Large Telescope team in Chile predicted that the discovered planet would be "rocky, and its mass too low to hold gas", as do the gas giants in the solar system such as Jupiter, Saturn and Neptune.
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