SUNRISES, sunsets, and suns that eclipse one another in a dance with the star daily, is what we see in the sky of Tatooine, the planet of the Skywalker family in Star Wars, a world that has become an icon in the imagination of science fiction and film. But it is less fanciful than it may seem. The space telescope of the Nasa Tess has discovered its first planet that is orbiting a pair of stars. And it seems that the presence of other worlds with a double sun is a rule more than an exception: already the telescope Kepler had found 12 in ten planetary systems. For Tess, launched in April 2018, this is a first time, and also for its discoverer, an intern in his last year of high school. And in the album of the new “hunter planets” will also be displayed in the first size of earth, orbiting in the so-called “band space” and could have liquid water on its surface.
the sky, two stars At the end of his last year of “High school” Wolf Cukier has carried out an internship at the Goddard Space Flight Center of Nasa in Maryland. Its task was to examine the data on the decrease of brightness of the star products from Tess. When he noticed an anomaly: “I Was looking for in the data that were checked in as binary to the eclipse, a system where two stars revolving about one another and from our point of observation eclipse in each orbit – says Cukier in the press release widespread by Nasa three days after the beginning of my internship, I saw a signal from a system called TOI 1338, at the beginning I thought it was an eclipse of the star, but the timing was wrong. It turns out that it was a planet”.
Cukier has become so co-author of the study describing the discovery, presented at the American astronomical meeting in Honolulu : a planet that is orbiting two stars, about 1,300 light-years from us, in the small constellation of the Painter, visible from the southern hemisphere. Being able to distinguish a planet in the dance of the two stars is a difficult task, because the signals confuse the algorithms. For this the intuition of the young student was crucial. For now, however, imagine a double sunset like the one on Tatooine, it is rather difficult: TOI 1338 b (each newly discovered planet gets its name from its star with the addition of the letters of the alphabet) has a mass between those of Neptune and Saturn. May not have a surface and an atmosphere like the earth to enjoy the spectacle.
Tess is only at the beginning of the work and is producing data to tons. With four rooms peering at the sky, taking a photo every 30 minutes for 27 consecutive days. When the light of a star dims, with a certain regularity, it may be due to a planet that passes in front of it. With this method (the so-called “transit”), Kepler has found over 2,700 planets confirmed up to 4,100 total.
A new ‘cousin’ of the Earth From October 2018, the second mission, Kepler (K2) has been declared ended, and the torch was passed on to Tess, who has to his credit just 37 planets. But between these, there is also his first world similar to our own. At least on paper and for the few data available. Orbit around a smaller star, and the cold of our Sun, is just 100 light-years away from us, so relatively close. It’s called TOI 700 d, the third of this star system: “Tess was designed and launched specifically to find planets size of earth in orbit around nearby stars, ” explains Paul Hertz, astrophysicist at Nasa, the planets around nearby stars are the easiest to follow with large telescopes from Ground and space”. The discovery was confirmed by the data of the Spitzer space telescope.
TOI 700 d is the outermost of the three planets around this star, the first and most interior has the same mass of the Earth, but it is very close. The second is two and a half times our planet while. The third is him: 20 percent larger than Earth, and at the right distance because it receives from its star, approximately 86% of the energy we receive from the Sun. Enough to raise the surface temperature above freezing. But there are drawbacks in this distant world: as to his other “brothers” of the same system, is in synchronous rotation: it means that exhibition to its sun, always the same hemisphere (as does the Moon with the Earth). One rotation a day, therefore, takes 37 of our but there is no alternation of light and darkness. While the face is constantly illuminated, and therefore very hot, the other is ice cold, always in the shade. None of us would want to live in a world like this. There are many planets in synchronous rotation, and very close to their stars like this, starting from the system of the Trappist, which has a population of at least two or three worlds within the band of habitability. The hope for any form of life, is to encounter favourable conditions in the zone of twilight, where the heat is infernal and frost and does not cling too much to the grip.
Atmosphere, and water for life, But there are still many questions to answer. The first and most important is if has or has not an atmosphere. The red dwarf as TOI 700 are the stars, the most common of the known Universe. They are cold and live many billions of years older than all the others. But they are ‘intemperate’, often produce flare-ups, eruptions, able to sweep away the atmosphere of a planet that does not have a magnetic field to make him a shield. However, TOI 700 according to astronomers seems to have been rather quiet, but we do not know how you have behaved in the last few billion years. The fate of a planet in the habitable zone, in fact, is related to many factors (take, for example, Venus, a planet in the habitable zone, with the mass of the Earth, but with a greenhouse effect that pushes the temperature to over 400 degrees).
The scientists of Nasa have already proposed some models, the hypothesis of how you might present, from the planet covered by a giant ocean, as was at one time the Mars, a Earth, but without water. To better understand this new ‘cousin’, is still a potential “twin” of the Earth, we have to wait for new tools that can peek at what there is in the atmosphere, by analyzing the spectrum of the light that filters through and comes up to us.
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