WorldNewly discovered planetary system allows to glimpse the future after the death...

Newly discovered planetary system allows to glimpse the future after the death of the Sun

An international group of scientists, with the participation of the Andalusian Astrophysics Institute (IAA-CSIC), discovered a planetary system formed by a Jupiterian planet, that is, similar to Jupiter, which orbits a white dwarf. This gas planet has a mass 40% greater than that of Jupiter, while the white dwarf has 60% of the mass of the Sun. The research was published in the magazine nature. Camilla Danielski, an astrophysicist at the IAA-CSIC and one of the study participants, points out that, with this discovery, “there is a guarantee that there are planets in our system that can survive the evolution of the star.” This could be a glimpse into the future of the Solar System when the Sun comes to an end and becomes a red giant 5 billion years from now.

The Sun, like other similar stars, evolves over thousands of years until it turns into a white dwarf, like the one that makes up the discovered planetary system. Pedro Amado, principal researcher at the CSIC’s Cármenes telescope, whose mission is to detect exoplanets, explains this process: “These solar-type stars [quando começam a se apagar] they go through a red giant phase, in which the outer layers are expanding as the star consumes the materials it has to generate energy, and there comes a time when these outer layers are thrown outwards. What is exposed is the core of the star, which is what we know as the white dwarf”.

The discovered planetary system was first seen in 2010 through the gravitational microlensing, a technique that is sensitive to cold planets and allows you to probe objects around all types of stars. The main difference from other detection methods is that this technique does not rely on the host star’s light. This system was later observed and photographed on several occasions with an infrared ray instrument from the Keck II telescope in the United States. When trying to study the host star, the team of scientists discovered that its light was not bright enough for it to be an adult star. Based on the characteristics, the researchers also ruled out that it was a neutron star, a black hole or a brown dwarf. So it had to be a white dwarf.

The researchers say that the separation between Jupiterian planets and these stars is usually five or six astronomical units (AUs, the average distance between the Earth and the Sun). This time, however, the orbital separation is 2.8 AUs. Furthermore, they point out that the planet and the host star were born at the same time.

Regarding the consequences of this work, Amado highlights that it is one of the first and most important steps to understand the complete history of the Solar System, understanding this history as “what will happen in the future”, and adds that it can help to understand the complete evolution of the systems. planetariums. Regarding what will happen in millions of years, Joshua Blackman, professor at the University of Tasmania (Australia) and lead author of the work, summarizes that the evolution of the Sun will destroy Mercury and Venus and possibly the Earth. Already Mars and the outer gas giant planets will survive. “Our discovery shows that the standard image of how planetary systems evolve as their host star dies is probably correct”, he details. Regarding the planets that survive, Danielski points out that they have to be within a separation from the star that is not too close, so that they are not eaten by it, nor too far away, so that they do not get lost in space. .

Past and future studies

These planetary systems have been studied for years, but with less success than in the last work. In September 2020 it was published in nature another poll that showed a possible candidate for a giant planet orbiting a white dwarf. It was about the same size as Jupiter and at most 14 times its mass, with 95% certainty. Danielski says the problem with that study is that the exact mass of the planet candidate is not known. Only the upper limit is known for sure — so it may or may not be a planet.

Pedro Amado and his colleagues at the IAA-CSIC maintain their intention to find other planetary systems like this one. This time, it will be through the Espresso instrument, a very high resolution and precision spectrograph that is on the VLT (a system of four telescopes) in Chile. This tool will measure radial velocity in meters per second. According to the Spanish Society of Astrophysics (SEA), radial velocity is “the speed at which a celestial object – usually a star – moves away from or approaches the Earth”. The objective is to detect a Jupiterian planet around a white dwarf, but much closer and that can be observed “as often as we want”, says the scientist.

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