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The human being may not be alone in the galaxy of the Milky Way. At least the possibility opens with the results of a study of 53 twin stars of the Sun carried out by researchers from the National Institute of Space Research (INPE), recently published in the Monthly Notices of the Royal Astronomical Society (MNRAS).
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The study badyzed the data collected by the telescope. Southern European Observatory (ESO) in Chile
The globe is made up of layers that look almost like an onion. In the center is the nucleus whose center is at a depth of about 6,370 kilometers, with a temperature of 6,000 ºC, similar to the surface of the Sun. Above, the coat is pasty, similar to that of a hot asphalt. , with a thickness of about 2 950 km and 100 ° C in its upper part and 3500 ° C in the deepest, at the interface with the nucleus. This is magma, which can be seen when it is expelled by volcanoes.
It is covered by the earth's crust, the most superficial and shallow layer of the planet, in which we live, with an average depth of 40 km. With the top of the solid mantle, it forms the lithosphere, 100 km thick, which is itself divided into gigantic rock plates, called tectonics, which float on the mantle of magma, transporting oceans and continents.
There are 10 of these large stone rafts – African, Antarctic, Arabic, Eurasian, Philippine, Indo-Australian, Nazca, North America and the Caribbean, Pacific and South America – and several smaller ones. It is these structures that shape the surface of the Earth, raising mountains and causing earthquakes and tsunamis when they collide. What makes these plates float and move around the mantle is a phenomenon called convection, which is a movement of material rising or falling in a fluid due to heat.
This is where thorium comes in. "It's an unstable element whose radioactive decay (turning into another element – in this case radio – and releasing energy during the process), as well as uranium (U) and potbadium (K), which provided will provide to the interior of the Earth for billions of years. Half years of energy (the other half comes from the secular cooling of all the inner layers of the planet) necessary to maintain mantle convection and continental plate tectonism, "says Milone .
This induces the carbon cycle by releasing much smaller amounts of CO2 (carbon dioxide) and methane (CH4), which makes possible thermal stability in the global atmosphere, creating conditions Natural and life changing scale of billions of years.
"Thus, the initial concentrations of these elements on a rocky planet contribute indirectly to the habitability on their surface, particularly because of their long period of disintegration (billions of years)," explains Milone.
The twins studied by the Inpe team have different ages ranging from 500 million to 8.6 billion years old. "So we can track the abundance of thorium throughout the evolution of the galaxy, as well as stars similar to the Sun," says Milone.
"Another study by American researchers had already shown that our star had a slight thorium deficiency compared to 13 of its twins (seven in common with our study), showing that such stars, if they had rocky planets, would provide reservoirs of sufficient internal energy for the appearance of life. "
The spectrograph, scientific instrument coupled to a telescope, allowing to record and badyze the "electromagnetic" chromatic spectrum of celestial bodies
In other words, research has shown that there is a large amount of available energy due to the disintegration of thorium to maintain mantle convection and tectonism on any rocky planets. may exist […] around the solar twin.
"What is most exciting is that it seems that this element is also abundant in former solar twins, which means that the galaxy can be full of life both in the world. Space and time, "says Botelho
. according to the estimates of Milone and Jorge Luis Melendez Moreno, of the Department of Astronomy of the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) of the University of São Paulo (USP), there should be to have about 100 million to 1 billion in the sun in the galaxy.
"It is only an order of magnitude, based on an extrapolation of what we know from studies of the solar neighborhood," Melandez explains.
Another group estimates that about 5% of solar twins may have planetary systems similar to ours (rocky planets relatively close to the Sun and distant gaseous giants).
"Thus, we say that there are between 5 and 50 million planetary systems similar to the solar system of our galaxy," says Milone. "It seems that we are not alone and therefore in the universe, but it is worth noting that the results of our work only open up possibilities for existence and maintenance of life , and no detection of extraterrestrial life itself. "
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