Astronomers have confirmed an exoplanet orbiting two suns similar to Luke Skywalker’s fictional home, Tatooine, in the 1977 movie Star Wars. Dubbed Kepler-16b, researchers had previously spotted the planet using the transit method, where astronomers look for a drop in the star’s light caused by the planet transiting in front of it.
This time, researchers spotted Kepler-16b using a process known as the radial-velocity method, which measures changes in light spectra caused by the orbiting planet. Because most stars in the Milky Way exist in binary systems, and most of the exoplanets discovered in these binary systems are within the system’s habitable zone, researchers expect this new method for spotting Tatooine-like planets to aid the search for extraterrestrial life.
TATOOINE EXOPLANETS OFTEN WITHIN HABITABLE ZONE
Few scenes in Star Wars are as visually stunning or as memorable as Luke Skywalker standing beneath the twin sunset of Tatooine. It not only captures the yearning of the lead character to explore beyond his humble home but also immerses the viewer in a decidedly alien environment.
Astronomers have already spotted several planets orbiting two suns, with many residing within their host stars’ habitable zones, the orbital altitude where water could theoretically exist on the planet’s surface. At one point, there was a fear that gas giants sometimes spotted in these orbits would make it hard for rocky exoplanets to exist there as well. However, a 2021 study found that “even binary star systems with giant planets are hot targets in the search for Earth 2.0.”
TELLTALE WOBBLE CONFIRMS KEPLER-16B
To confirm Kepler-16b, the research team employed the Observatoire de Haute Provence, a telescope in France known for spotting the first exoplanet orbiting a sun-like star. The team chose this particular telescope because, unlike NASA’s Kepler and Transiting Exoplanet Survey Satellite (TESS) missions which used the transit method to spot exoplanets, the French telescope uses radial velocity to make its planetary detections.
According to a press release, after the French telescope captures the data, it “graphs into a line, but the line “wobbles” as the planet orbits around the two stars, producing a shaky line in the spectra of light.” That telltale wobble tells astronomers they have found a planet and may also yield critical data about the world, including its mass.
“It’s a confirmation that our method works,” said David Martin, co-author of the study and NASA Sagan Fellow in The Ohio State University’s Department of Astronomy. “And it creates an opportunity for us to apply this method now to identify other systems like this.”
Previously, astronomers had only spotted planets in binary star systems using the transit method since efforts to discover them using the radial velocity method had proven difficult.
“What people had faced was that having two sets of spectra from two stars makes it tricky, and people were struggling to get enough precision to see the wobble caused by the planet,” said Martin. “And we got around that by making a survey of systems with two stars that orbit each other where one star is big, and one is quite small.”
WATCH OUT, TATOOINE, WE ARE COMING!
Kepler-16b is a gas giant like Neptune, so it is unlikely to host life as we know it. Nonetheless, this latest study announces to those astronomers looking for planets capable of hosting extraterrestrial life that they have a new tool in their arsenal.
“Life is far most likely to evolve on planets located within their system’s Habitable Zone, just like Earth,” said Dr. Nikolaos Georgakarakos, a research associate from the Division of Science at New York University, Abu Dhabi, when announcing his team’s discovery of five exoplanets in the habitable zone of binary star systems. “Watch out, Tatooine, we are coming!”
Follow and connect with author Christopher Plain on Twitter: @plain_fiction