An exoterre does exist in the habitable zone of Proxima Centauri, the closest star to us

An international team of researchers has just confirmed the existence of the extrasolar planet Proxima Centauri b with the Espresso spectrograph installed on the VLT. These are the most precise measurements obtained to date.

Presented to the public on August 24, 2016, the planet Proxima Centauri b orbit around thestar closest to Solar system, located at 4.2 light years only. At the time, a perturbation in the speed having a direction and an intensity is represented by a vector, the speed vector. Relative speed is the speed of a body in relation to another or in relation to a benchmark. “Data-image =” 9 / 319daf63f4_77541_leibniz-dp.jpg “data-url =” “data-more =” Read the definition “>speed radial of Proxima Centauri had been measured, at the borders of the resolution instruments of the time. But thanks to spectrograph Espresso, the most precise ever built, and mounted on the In 1993, ESO launched the VLT (Very Large Telescope) project and decided to install it on the Cerro Paranal site, in the Chilean Andes, where the climate is particularly favorable to astronomical observations. It … “data-image =” “data-url =” .com / sciences / definitions / univers-vlt-2147 / “data-more =” Read more “>VLT in Chile, researchers were finally able to refine their measurements.

What is the radial velocity method?

Proxima b was discovered thanks to the radial velocity method, also called Doppler spectroscopy, consisting in identifying the variations of For example, an acoustic spectrum represents the intensity … “data-url =” / “data-more =” Read more “>spectrum luminous emitted by a star. The latter has a unique spectroscopic signature (a radial speed), informing us of its Unit of mass: the kilogram
The mass is represented by the symbol m and, in … “data-image =” “data- url = “” data-more = “Read more”>mass, its orbit and its period. When a planet orbits the star, it causes a Doppler effect modifying its radial speed. It is a bit like being in front of a stopped ambulance, and a pedestrian walking around the vehicle causes changes in the height of its siren, as when it is approaching or moving away. The reasons for this oscillation are spread over a period equal to that of the revolution of the planet around its star (or the pedestrian around its ambulance).

Artist’s impression of Proxima Centauri b, orbiting its star. © Gabriel Pérez Díaz, SMM (IAC)

Proxima b: confirmed existence

While at the time of the discovery of Proxima b, the Harps instrument measured a variation in radial speed of one meter per second, Espresso, for its part, was able to provide astronomers four times better resolution, 30 cm / s. “ It was essential to confirm the existence of Proxima b, explains Jonay González Hernández, co-author of the study, published in the review Astronomy & Astrophysics. It is one of the most interesting planets in the vicinity of our The Sun is the closest star to Earth, from which it is distant about 150 million kilometers. The Sun is located 8.5 kparsecs from the center of the Milky Way. In the classification of stars, the sun is a G2 type star.
The mass … “data-image =” “data-url =” https: // news. “data-more =” Read more “>Sun. Its mass, similar to that of the Structure of the globe … “data-image =” ” data-url = “” data-more = “Read more”>Earth, the fact that it could harbor life, and its proximity, make it an ideal candidate in the search for biomarkers with the next generation of telescopes
” A second signal was identified by the spectrograph, the nature of which remains to be determined. If it is indeed a planet, it could have a mass 3 times less than that of Earth.

New exoplanets on the horizon

Fruit of years of international collaboration, Espresso entered service at VLT in 2018. By combining the high precision of the spectrograph with the ability of the giant VLT to collect light, the researchers are hopeful of being on the path to new wave of exoplanetary exploration. ” Espresso has demonstrated that it can do much better than previous spectrographs, comments Alejandro Suárez Mascareño, lead author of the study. A new scenario is opening up. So far, we have been limited to the discovery of planets with a mass several times that of Earth, or, ultimately, the mass of an Earth, orbiting around cold stars. With Espresso, these constraints are lifted

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