After Proxima B and Chik, here’s the latest, Proxima D: Astronomers have discovered a new planet orbiting the star Proxima Centauri very close to our solar system, it was published in the journal Astronomy & Astronomy on Thursday.
At only a quarter of Earth’s weight, it is one of the lightest on the list of exoplanets, with about 5,000 planets orbiting stars other than the Sun.
Proxima Centauri is located four light years from our Sun. Smaller and twice as cold as him, it belonged to the genus “Red Dwarfs”.
But the star may be close and not large – so not so dazzling – that it is difficult to find planets in its lap. This is because when we look at the “proxima system”, the Earth, the exoplanet and its star are not in the same plane: the so-called “easy” mode of transport that captures the resulting luminosity variations cannot be used. By passing a planet in front of its host star like a micro eclipse.
Therefore, it was necessary to use the method of radial velocities that measure the velocity of a star, by observing whether it is approaching or moving towards us. If the planets orbit, this speed will vary slightly.
Thus discovered a few years ago, Proxima B, which has Earth-like mass, is in the “habitable” zone (not too close to or too far from the star), and Proxima C is small.
Signal of the 2nd planet
“When we found them, we suspected a signal coming from a third planet,” said AFP Baptiste Lavie of the University of Geneva’s Department of Astronomy (ESO) in Chile.
But the signal was so weak that it was necessary to continue observations with the ESPRESSO spectrograph installed on the VLT. A small variation in the speed of the star (1.4 km / h) was confirmed by a nearby planet.
Proxima D is 4 million kilometers from its star and less than one tenth of the distance from the Sun to Mercury.
Located on the border of the habitable zone, it takes only five days to complete its revolution.
According to astronomer Baptist Lavi, it’s like the gas giants of the solar system, Jupiter, Saturn or Neptune, which is “definitely a rocky planet, and its mass is too small to hold gas”.
Pedro Figueroa, head of the ESPRESSO instrument in Chile, analyzes that “this most important discovery shows the potential of a radial velocity system that can detect populations of light-like planets like ours, which can be very large and life-giving in our galaxy.” , Quoted in the ESO press release.