Astronomers believe planets like Jupiter shield us from space objects that would otherwise slam into Earth. Now, they’re closer to learning whether these also guard solar systems elsewhere in the galaxy.
A UCR-led team has discovered two Jupiter-sized planets about 150 light years away from Earth that could reveal whether life is likely on the smaller planets in other solar systems. Stephen Kane, lead study author and UCR associate professor of planetary astrophysics, said:
“We believe planets like Jupiter have profoundly impacted the progression of life on Earth. Without them, humans might not be here to have this conversation.
“Understanding how many other stars have planets like Jupiter could be very important for learning about the habitability of planets in those systems.”
Along with liquid water oceans, Kane said astronomers believe such planets can act as “slingshots,” pulling objects like meteors, comets, and asteroids out of their trajectories en route to impact with small, rocky planets.
Many larger planets have been found close to their stars. However, those aren’t as useful for learning about the architecture of our own solar system, where the giant planets — including Saturn, Uranus, and Neptune — are all farther from the Sun. Giant planets far from their stars have, until now, been more challenging to find.
A recent study in the Astronomical Journal details how Kane’s team succeeded in a novel approach combining traditional detection methods with the latest technologies.
One popular method of searching for exoplanets — planets in other solar systems — involves monitoring stars for “wobble,” in which a star moves toward and away from Earth. The wobble is likely caused by the gravitational pull a nearby planet exerts on it. When a star wobbles, it’s a clue there may be an exoplanet nearby.
The ‘wobble’ technique: The blue wave shows movement toward Earth, and the red occurs as the star heads away. (Image: JPL-Caltech via NASA)
The gravitational pull is weaker when the planet is far from its star, making the wobble smaller and more challenging to detect. The other problem with using the wobble detection method, Kane said, is that it just takes a long time. Earth only takes a year to orbit the sun. Jupiter takes 12, Saturn takes 30, and Neptune takes 164 years.
Giant planets were discovered by using wobble and imaging method
The larger exoplanets also take many years to circle their stars, which means observing a complete orbit could engulf an astronomer’s entire career. Kane and his team combined the wobble method with direct imaging to accelerate the process. This way, if the team thought a planet might be causing the wobble, they could confirm it by sight.
Obtaining a direct image of a planet quadrillions of miles away is no simple task. It requires the largest possible telescope, which is at least 32 feet long and highly sensitive. Even from this distance, the light of the stars can overexpose the image, obscuring the target planets.
The larger exoplanets also take many years to circle their stars, which means observing a complete orbit could engulf an astronomer’s entire career. (Image: JPL-Caltech via NASA)
The team overcame this challenge by learning to recognize and eliminate the patterns in their images created by starlight. Removing the starlight allowed Kane’s team to see what remained. Kane said:
“Direct imaging has come a long way both in terms of understanding the patterns we find, and in terms of the instruments used to create the images, which are much higher resolution than they’ve ever been.
“You see this every time a new smartphone is released — the camera detectors are always being improved and that’s true in astronomy as well.”
The team applied wobble and imaging methods to 20 stars in this project. In addition to the two being orbited by giant Jupiter-like planets that had not been previously discovered, the team also detected a third, previously observed star with a massive planet in its system.
In the future, the team will continue to monitor 10 of the stars where planetary companions could not be ruled out. In addition, Kane is planning a new project to measure how long it takes these exoplanets to complete rotations toward and away from their stars, which cannot currently be measured. Kane concluded with:
“This discovery is an important piece of the puzzle because it helps us understand the factors that make a planet habitable and whether that’s common or not.
“We are converging rapidly on answers to this question that the past 3,000 recorded years of history could only wish they had available to them.”
Provided by: Jules Bernstein, University of California — Riverside [Note: Materials may be edited for content and length.]
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