The planets whose existence is confirmed around other stars, besides the Sun, already are around 2000. An international team of scientists, which includes two Portuguese, has now discovered an extrasolar planet, or exoplanet, distinguished the other:. is rocky, it has an atmosphere and is close to us, or almost, since being 39 light-years away is, astronomically speaking, next door
Let us present this new world rocky revealed in the issue of Thursday’s journal Nature : it is called GJ 1132b, orbits a red dwarf, a class of smaller stars than the Sun, it is rocky like Mercury, Venus or Earth and it is not much larger than our planet. It has 1.6 times the mass of Earth and 1.2 times its diameter. And above all, is the first rocky planet when it detects an atmosphere, after 20 years of extrasolar planets discovered since October 1995.
The planet GJ 1132b was initially discovered with the method of transits, which detects small decreases in the light from a star when a planet passes in front of him. These regular micro-eclipses denounce the presence of this planet (since it does not shine like a star) and determining its diameter. These first observations with robotic telescopes in the Inter-American Observatory Hill Tololo (in Chile) – as part of a project that observes red dwarfs, the most common stars in our galaxy, up to 100 light-years away looking for similar planets Earth – and then were confirmed in other telescopes
Later, the team determined the mass of the planet using other planets detection method, the radial velocity, which measures small periodic variations in speed. a star, which sometimes moves away slightly of us, now approaching due to the gravitational attraction of a planet also exerts on it. These small jerks caused by gravitational this planet determining its mass and together with the diameter, it is possible to calculate the density. From here, you can tell what is their composition. – It is gaseous, like Jupiter and Saturn, or rocky, as concluded in the case of GJ 1132b
On this planet, a year only lasts 1 6 days, the time to complete a return to the red dwarf. This means that it is only 2.2 million kilometers from the star, which is very close, if we look at Mercury, the planet of our solar system closer to the Sun and yet it is distant 55 million kilometers.
But this closeness between the planet GJ 1132b and the red dwarf makes this hot planet more to have liquid water to flow on its rocky surface, where, who knows, maybe encontrássemos mountains and valleys. But at the same time, it is no longer hot to have an atmosphere – like Venus, judge the team -., Because its red dwarf is only 20% the size of the Sun “Therefore, it is estimated that the temperature the planet will be only between 135 and 305 degrees Celsius. This temperature is much lower than that of any other known rocky exoplanet “, says a statement from the Institute of Astrophysics and Space Sciences (IA), in Lisbon and Porto, to which he belongs Nuno Santos, one of the authors of the article in . Nature (the other Portuguese who signs this work is Vasco Neves, now working in Brazil)
This is not, however, the rocky exoplanet closer to the earth: this status at least for now, it is the HD219134, 21 light years away, and whose discovery was announced in July by a team that is part Pedro Figueira, IA. “It has 1.6 times the diameter and 4.4 times the mass of Earth. However, the temperature should be around 700 degrees Celsius, ie, it is too warm for it to be any atmosphere, “says Ricardo Cardoso Reis us, the IA science communication office. “So far, all measurements of exoplanet atmospheres were just giants like exoJúpiteres or exoNeptunos, which are very close to their stars. Due to this proximity, the planet’s atmosphere is heated and expands, so the amount of light passing through it is higher and is relatively easier to spot [by using the method transits]. “
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