a Tatooine-like exoplanet orbiting two stars

Happy Star Wars Day! And on May 4and to be with you.

Like Tatooine – the homeworld of Anakin and Luke Skywalker – a rare exoplanet with its own binary sunset (but in our galaxy, the Milky Way) was spotted by astronomers earlier this year using a telescope on the ground.

We all know the best movies come from trilogies, like star wars and A Space-Time Trilogy with Jared Kaplan – an entry to the 2021 SCINEMA International Film Festival. In the series, Jared Kaplan, theoretical physicist at Johns Hopkins University in the United States, turns to black holes, gravity and even a glare of zebras, to examine deep and whimsical questions about space-time and our universe.

Watch the full trilogy here.

A rare exoplanet orbiting two stars at once has been spotted by researchers using a ground-based telescope, in a never-before-seen demonstration that cheaper, ground-based methods could be used to find such rare planets.

The exoplanet, Kepler-16b, is 245 light-years from Earth and, much like the homeworlds of Luke Skywalker (Tatooine) and Doctor Who (Gallifrey), has two sunsets a day as it drifts around of its twin stars. It was discovered 10 years ago by NASA’s Kepler satellite.

Kepler-16b orbits two stars, and these two stars orbit each other. Pairs of stars that orbit each other, known as binary systems, are not uncommon in themselves – estimates vary, but CSIRO predicts that up to 85% of all stars are found in binary systems. But circumbinary planets (planets that orbit these twin stars) are rare, and before Kepler-16b, we only knew of ten.

In fact, scientists don’t know how circumbinary planets can exist. Typically, planets are formed from the mass of dust and gas that surrounds a young star, known as the protoplanetary disk. But this process may not be possible in a binary system.

“This is because the presence of two stars interferes with the protoplanetary disk, which prevents dust from clumping into the planets, a process called accretion,” says lead researcher Amaury Triaud, from the University of Birmingham. “Using this standard explanation, it is difficult to understand how circumbinary planets can exist”

The team observed the exoplanet using a telescope based at the Observatoire de Haute-Provence, France. They were able to detect the exoplanet using the radial velocity method, observing the change in speed of a star as a planet orbits it.

The researchers say this demonstration is important because it shows that we can detect exoplanets using cheaper and more efficient methods. They say the radial velocity method is more sensitive to additional planets in a system and can also measure a planet’s mass.

Most star systems in the universe are probably binary systems – two stars orbiting each other. But planets that orbit two stars (like Tatooine in the Star Wars series) are rare and would experience two sunsets. Image credit: NASA/JPL-Caltech

They hope to continue the search for more circumbinary planets and hopefully answer the pressing question of how these planets formed.

“The planet may have formed away from the two stars, where their influence is weaker, and then moved inward in a process called disk-driven migration,” Triaud says. “Or, alternatively, we might find that we need to revise our understanding of the planetary accretion process.”

Isabelle Boisse, from the University of Marseille, is the scientist in charge of the SOPHIE instrument used to collect the data.

“Our discovery shows how ground-based telescopes remain highly relevant to modern exoplanet research and can be used for exciting new projects,” Boisse said. “Having shown that we can detect Kepler-16b, we will now analyze data taken from many other binary star systems and search for new circumbinary planets.”

The study is published in Royal Astronomical Society Monthly Notices.

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