Planetary neighbors can influence habitability, for better or worse

April 4 (UPI) — Even after a planet has trapped sufficient amounts of liquid water to sustain life, giant neighbors can significantly alter the planet’s habitability, according to a new study.

Rocky planets with an atmosphere and orbit that allow for the existence of liquid water are said to lie in the habitable zone. For an exoplanet, a stable orbit inside the habitable zone doesn’t guarantee habitability in perpetuity.

New research suggests neighboring giant planets can have a sizable influence on whether or not an exoplanet remains habitable. More often than not, giant neighbors have a negative impact on an exoplanet’s habitability.

Planetary scientists at New York University Abu Dhabi and NASA’s Jet Propulsion Laboratory studied 147 extrasolar planetary systems with giant planets. They found giant neighbors can negatively affect an exoplanet’s habitability even without altering its orbit.

“While in the majority of investigated systems the presence of the gas ‘giants’ shrank the habitable zone, they still left sufficient room for habitable Earth-like planets to be there,” Nikolaos Georgakarakos, a researcher in the department of physics at NYU Abu Dhabi, said in a news release. “This is an important insight to inform follow-up investigations. It would not make sense to search for Earth 2.0 in a system where a giant planet stirs the orbit of any neighboring terrestrial planet in the habitable zone so much that its climate collapses.”

However, a giant neighbor can sometimes help stabilize an exoplanet’s orbit, keeping the planet within the habitable zone.

“Under certain conditions, the presence of a giant planet can actually increase the size of the habitable zone, which is the area where your terrestrial planet receives the right amount of light in order to support liquid water on its surface,” said Siegfried Eggl, an associate researcher at JPL. “This is quite remarkable since the continuous gravitational pull of giant planets on their terrestrial neighbors mostly spells trouble for habitability.”

The scientists published their findings in a new paper published this week in the Astrophysical Journal.

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