Des astronomes précisent l’avenir du Soleil et sa fin

Illustration du lever d'une géante rouge au-dessus d'une planète rocheuse. © Pavel, Adobe Stock

You may also like

[EN VIDÉO] Mission Gaia: The Milky Way will soon be mapped
ESA’s Gaia mission has measured the positions and velocities of a billion stars in the Milky Way. This will allow us to reconstruct the history of our galaxy, better understand its structure, but also search for dark matter and exoplanets.

The dazzling progress of nuclear astrophysics after World War II, complementing the equally rapid constitution during the 1930s of stellar structure theory, gave us clues to the life and death of stars. stars, and therefore of course the one that worries us the most: the Sun is the closest star to Earth, from which it is approximately 150 million kilometers away. The Sun is 8.5 kparsecs from the center of the Milky Way. In stellar classification, the sun is a G2-type star.
The mass…” data-image=”” data-url=”https://news.” data-more=”Read more”>Sun.

There are still several unknowns on these issues and we know that the third phase of publication of the ESA Gaia satellite has been carried out. June 13, 2022 will be helpful in this regard. Let’s remember that gaia is an astrometry mission intended to provide us with more accurate determinations of velocity that has a direction and intensity represented by a vector, the velocity vector. Relative velocity is the velocity of one body relative to another or relative to a reference point.” data-image=” 9/319daf63f4_77541_leibniz-dp .jpg” data-url=”” data-more=”Read definition”>gears and positions in From Earth, only a cross section can be seen…” data-image=” 777b761907_120668_milkyway-galaxy .jpg” data-url=”” data-more=”Read more”>Milky Way of more than a billion stars.

Gaia must also provide determinations of the brightness apparent and sometimes the color…” data-image=”” data-url=” https:/ /” data-more=”Read more”>color of these stars. Knowing the temperature that determines the color of a star according to the famous Wien’s law and the distance of a star, an absolute luminosity can be extracted from it and a version of the famous diagram of the astronomers The Danish and American Ejnar Hertzsprung and Henry Norris Russell.

They proposed it independently in the early 1910s and it was initially intended to show how the known stars of the Milky Way were distributed in a diagram that gave the luminosity and spectral class of these stars or their absolute magnitude depending on its temperature. We then obtain a “z” distribution seen in a mirror with a transverse band where most of the stars are concentrated and which we call the main stream (main stream in English).

stars of different masses they spend most of their lives on this tape from birth but then switch places until they leave the main sequence at the end of their lives. A better determination of the These parameters are not independent, they allow to classify the stars in a small number of families. This is how we distinguish main sequence stars, white dwarfs, blue giants,…” data-url=” 3732 /” data-more=”Read more”>Hertzsprung–Russell diagram (HR) will therefore affect what we know about the life and death of stars.

A presentation of the first results of Gaia a few years ago. © European Space AgencyTHIS

5,863 analogs of the Sun discovered by Gaia

In a recent ESA press release, astronomer orlagh creevey, who works at the Observatoire de la Côte d’Azur, explains that this is what happened thanks, in particular, to the work she and her colleagues have done on the latest Gaia data. This new diagram contains so much very precise information that astronomers were able to identify fine details that had never been seen before, allowing them to learn more about the fate of the Sun.

To do this, Orlagh and his colleagues looked for stars with temperatures, gravity of surface, compositions, masses and radii that are all similar to the current Sun. They found 5,863 stars that matched their criteria in the Gaia data. But since these analogs of the Sun are not all located in the same places on the HR diagram, we can deduce that they represent different points in our star’s past and future evolutionary path.

In fact, while a star’s mass changes relatively little during its lifetime, the star’s temperature and size vary considerably as it ages, becoming, for example, a red giant, then a red giant. white dwarf (white dwarf in English). These changes are driven by the types of reactions of nuclear fusion that take place inside the star, such as the beginning of the fusion of atoms General
Symbol: He Atomic number: 2 Electrons per energy level: 2 Atomic mass: 4,003 u Most stable isotopes:…” data-image=” 9 / a/e/9ae62bedde_70382_zepplinheliumjpg.jpg” data-url=”” data-more=”Read More”>heliumand by the location within the star of these reactions.

The new statistics thus compiled allow us to conclude that the Sun will reach its maximum temperature in just under 4,000 million years and that it will become a red giant between one and three billion years later. Earth will have become uninhabitable long before, the evolution of the luminosity of the sun leading to the evaporation of these oceans in about a billion years.

Hertzsprung-Russell diagrams drawn with data from Gaia. The evolutionary path of the Sun, inferred from that of similar stars in the Gaia data, is shown. © ESA, Gaia, DPAC, CC by-sa 3.0, IGO

Are you interested in what you just read?

#Des #astronomes #précisent #lavenir #Soleil #fin

Leave a Reply

Your email address will not be published.