The incredible discovery of the planet Tatooine will awaken the Jedi in you

Kepler-16b is a rare planet orbiting two stars at the same time. It is also called an exoplanet. It has just been rediscovered by the Haute-Provence observatory under the supervision of the CNRS. And if you don’t understand something, we’ll explain everything to you.

Kepler-16b might be renamed Tatooine because it’s a place where you would see exactly the same view as Luke Skywalker: an atmosphere drenched in fog with two very different sunsets across the sky.

No, you are not dreaming, reality goes far beyond fiction. And if astronomy seems like a completely unknown universe to you, then this article is for you.

Let’s go back to the beginning and lay the groundwork. Our planet earth revolves around a star, the sun. When the larger star emits heat and energy, the smaller planet receives it.

Our solar system has eight planets orbiting the sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune (from closest to most distant).

And the stars we see in the sky late at night are sun-like stars. These core-dense spheres appear small, but that’s really only because they’re extremely distant. They can therefore be as big as the sun or even much bigger for many of them.

So the question is: don’t the stars also have planets that attract and orbit around them, in addition to the sun?

to there are also many questions: what are the properties of the planets beyond the solar system? Are some similar to earth? Is there extraterrestrial life? Everything pushes, but above all fascinates.

The good news is that from a scientific point of view, answers have been provided with the discovery of these exoplanets (planets orbiting a star other than the Sun).

For a long time nobody managed to discover them. And when we suspected they existed, we were burned alive. At least that’s what happened to the Neapolitan philosopher Giordino Bruno in 1600. A great visionary, but unfortunately also a martyr of science.

Centuries later, his theory will be confirmed. In 1995, the first extrasolar planet (exoplanet) was discovered by two Swiss astronauts, Michel Mayor and Didier Queloz, from the Observatoire de Haute Provence. An incredible discovery that also earned them the 2019 Nobel Prize in Physics, it’s called 51 Pegasi b (named after the constellation).

Almost 5,000 exoplanets have been discovered in 20 years. The simplest method, direct imaging, is as follows: “We take a big telescope, we magnify it, and we see that the little dot rotates around the star. But in reality the planet is too far away and the star emits too much light, which is equivalent to an observation from 1000 kilometers , a bird circling a lighthouse. Not easy to spot…” explains Guillaume Herbard, astronomer at the Observatoire de Haute-Provence.

Even more so when we learn that many stars are binary, i.e. rotate with each other. So finding a planet revolving around a binary star is an impossible mission? You will be surprised.

In 2011, the satellite (space telescope) Kepler (which will give its name to the planet) achieves the unthinkable. It detects a shape that passes in front of each of the two stars from time to time because the light is fading at that time. He concludes that it is one of the first identified circumbinary planets (a planet orbiting a binary star).

According to the analyses, Kepler 16-b orbits both stars in 228 days.

February 2022. What could be distinguished in space is confirmed again on Earth, near Forcalquier and Manosque, from the Observatory of Haute-Provence.

An even more sophisticated and powerful technique led an international team of 33 scientists led by Frenchman Amaury Triaud to rediscover this planet: the radial velocity method. A historical method, cheaper than using space satellites.

“We can express the motion of the star in radial velocity, which is the speed between us and the star, is it approaching or receding?” shows Guillaume Hebrard, astrophysicist and research director at the CNRS at the Observatoire de Haute-Provence.

Astronomers observe a change in a star’s speed as a planet revolves around it.

“We observe the two stars with a terrestrial telescope. Their light is analyzed and with the Sophie spectroscope we can measure their movement, similar to how radar works on freeways.” continues the astronomer.

Working closely with the University of Birmingham and the Marseille Astrophysics Laboratory, the team then managed to determine that these stars (which attract each other due to gravity) rotate around each other in 41 days. And, additional discovery, the planet even makes the stars move.

This method also makes it possible to measure one of the fundamental properties of a planet: its mass. Kepler-16b’s is one-third that of Jupiter (a planet ten times larger than Earth), but its radius is scarcely smaller than Jupiter’s.

It is a gas giant, a planet composed mostly of light gases like hydrogen and helium, like Jupiter. Simply put, you couldn’t walk on its surface because it’s kind of an atmosphere. Conversely, Earth is a solid (or telluric) planet.

We then imagine a whole series of science fiction scenarios, in particular that of the famous Star Wars. “For my colleagues it was the holy grail! When they discovered this planet, they immediately referred to Luke Skywalker. It was the first time we encountered such an interesting and difficult to recognize phenomenon! is always pleasant, especially when one feels that there is significant progress and there is!” exclaims Guillaume Hébrard on the line.

This corresponds to five years of observations. Kepler-16b is the first circumbinary planet discovered using the radial velocity method and the only one currently known in this case.

The team plans to continue their observations by searching for previously unknown circumbinary planets and helping answer questions about planet formation.

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