Massive gas planets can be agents of chaos, ensuring that nothing lives on their Earth-like neighbors in the vicinity of other stars. According to new research, giants in some planetary systems tend to kick smaller planets out of orbit, wreaking havoc on their climates.
Jupiter, our solar system’s largest planet, plays an important protective role. Its massive gravitational field deflects comets and asteroids that would otherwise collide with Earth, assisting in the creation of a stable environment for life. Giant planets in other parts of the universe, on the other hand, do not always protect life on their smaller, rocky planet neighbors.
A new Astronomical Journal paper describes how the gravitational pull of massive planets in a nearby star system is likely to push Earth-like planets out of the “habitable zone.” This zone is defined as the range of distances from a star where liquid water can exist on a planet’s surface, allowing life to exist.
The four giant planets in HD 141399 are farther from their star than most other known solar systems. As a result, it’s a good model for comparing to our solar system, where Jupiter and Saturn are also relatively far from the sun.
The papers demonstrate how rare it is to find the right set of circumstances to support life elsewhere in the universe. Our work gives us more reasons to be very grateful for the particular planetary configuration we have in our solar system.
Stephen Kane
“It’s as if they have four Jupiters acting like wrecking balls, throwing everything out of whack,” said Stephen Kane, UC Riverside astrophysicist and author of the journal paper.
Taking data about the system’s planets into account, Kane ran multiple computer simulations to understand the effect of these four giants. He wanted specifically to look at the habitable zone in this star system and see if an Earth could remain in a stable orbit there.
“The answer is yes, but it’s extremely unlikely. There are only a few places where the giants’ gravitational pull would not knock a rocky planet out of its orbit and send it flying right out of the zone,” Kane said.
While this paper shows giant planets outside the habitable zone destroying the chances for life, a second, related paper shows how one large planet in the middle of the zone would have a similar effect. This second paper, also published in the Astronomical Journal, investigates GJ 357, a star system only 30 light years away from Earth. The galaxy’s diameter is estimated to be 100,000 light years, so this system is “definitely in our neighborhood,” according to Kane.
“It’s possible GJ 357 d is as much as 10 Earth masses, which means it’s probably not terrestrial, so you couldn’t have life on it,” he said. “Or at least, it would not be able to host life as we know it.”
Kane and his collaborator, UCR planetary science postdoctoral scholar Tara Fetherolf, show in the second part of the paper that if the planet is much larger than previously thought, it is certain to prevent more Earth-like planets from residing in the habitable zone alongside it.
In the second part of the paper, Kane and his collaborator, UCR planetary science postdoctoral scholar Tara Fetherolf, demonstrate that if the planet is much larger than previously believed, it is certain to prevent more Earth-like planets from residing in the habitable zone alongside it.
Though there are a few places in this system’s habitable zone where an Earth could potentially live, their orbits around the star would be highly elliptical. “In other words, the orbits would produce crazy climates on those planets,” Kane went on to say. “This paper is really a warning, when we find planets in the habitable zone, not to assume they are automatically capable of hosting life.”
Finally, the papers demonstrate how rare it is to find the right set of circumstances to support life elsewhere in the universe. “Our work gives us more reasons to be very grateful for the particular planetary configuration we have in our solar system,” Kane went on to say.
