A planet with two suns named Kepler 16-b was located using conventional astronomy last week. Discover why this is an important breakthrough that will lead to a better understanding of how planets form.
When I was in high school, the original Star Wars movie was a genuine blockbuster. Everyone loves a story about a hero’s journey.
It won seven academy awards including Best Visual Effects and Best Original Score. These were well-deserved because both of those aspects of the film were spectacular.
Unfortunately for the cast and crew, they were up against Woody Allen’s masterpiece Annie Hall that year, which put Best Picture, Best Director and Best Original Screenplay out of reach. Even so, it’s arguably the most influential science fiction movie ever made.
Luke Skywalker’s Desolate Home Planet, Tatooine
One of those award winning special effects involves Luke Skywalker’s desolate home planet, Tatooine. His home world is a planet with two suns, and the twin sunsets depicted in the film are captivating.
Back when George Lucas made the film, nobody knew if there were planets outside our solar system. Today, planetary scientists have identified just under 5,000 of them.
It was only a matter of time before a planet like the fictional Tatooine would present itself. Professor Laurance Doyle of the SETI Institute discovered one in 2011 using the space observatory onboard NASA’s Kepler Spacecraft.
Cirumbinary Planet About the Same Mass as Jupiter
It’s called Kepler 16-b, and it’s what astronomers call a circumbinary planet. It’s about the same mass as Jupiter or Saturn.
It’s orbiting a binary star system about 245 light-years from Earth. Someone on its surface could indeed watch a twin sunset, just like in the movie.
We’d never managed to locate Kepler 16-b from the ground, but that changed last week. A team from the University of Birmingham announced in the Monthly Notices of the Royal Astronomical Society that they’d spotted it using the 193 cm SOPHIE telescope at France’s Obervatoire de Haute-Provence.
Scientists Monitor Changes in a Star’s Brightness
The Kepler Space Telescope identified its first planet with two suns using the transit method. In that technique, scientists monitor changes in a stars brightness, hoping to spot the dip in liminosity caused when a planet moves across the face of a star.
The ground-based team used a different approach called the radial velocity method. This technique identifies subtle changes in a star’s speed caused by the gravity of the planet orbiting around it.
Circumbinary planets are a puzzle for astronomers. The planets in our Solar System formed out of a disc-shaped mass of dust and gas left over from the formation of our Sun.
How Binary Stars Could Have a Protoplanetary Disk
Scientists have difficulty working out how a pair of binary stars could have the same kind of protoplanetary disc. The combined gravity of the two stars would distort the shape of the disc, preventing planets from forming from it.
Professor Amaury Triaud of the University of Birmingham led the research team. He has a working hypothesis about how Kepler 16-b might have emerged.
“The planet may have formed far from the two stars, where their influence is weaker, and then moved inwards in a process called disc-driven migration – or, alternatively, we may find we need to revise our understanding of the process of planetary accretion.”
Feasible to Detect Circumbinary Planets from the Ground
Demonstrating that it’s feasible to detect a planet with two suns from the ground is a major breakthrough. It means that astrophysicists no longer have to rely on costly and scarce space telescopes to look for more of these unusual planets.
Not only that, the radial velocity technique works better for finding additional planets in a system. Because it’s gravity-based, it also enables scientists to determine the mass of an exoplanet, which is the main thing they’re working to discover.
Most of us have asked ourselves whether there might be life on other planets. Understanding the process by which planets form around stars, including binary stars, is a vital step toward answering that fundamental question.
Most Astronomy Comes from Ground-Based Telescopes
Since the begininng of the Space Race in the late 1950s, space exploration has captured the public’s imagination. Yet it’s important for lay people to realize that the vast majority of what we know about our Universe comes from the work of conventional astronomers using ground-based telescopes.
Dr. Isabelle Boisse of the University of Marseille is in charge of the SOPHIE telescope. She summarized the team’s findings this way.
“Our discovery shows how ground-based telescopes remain entirely relevant to modern exoplanet research and can be used for exciting new projects. Having shown we can detect Kepler-16b, we will now analyse data taken on many other binary star systems, and search for new circumbinary planets.”
We always have more to learn if we dare to know.
Learn more:
‘Tatooine-like’ exoplanet spotted by ground-based telescope
BEBOP III. Observations and an independent mass measurement of Kepler-16 (AB) b – the first circumbinary planet detected with radial velocities
Astrobiology: 3 Questions We Need to Answer
Planet Formation Clarified by Young Star System
Earth-Like Planets Orbit Half of All Sun-Like Stars
