Planets that move around their stars in circular orbits are a better bet for life than those in elongated orbits when it comes to creating habitable climate conditions, according to a new study.
That’s because circular orbits tend to have more stable climates, while an overly elliptical orbit could send a planet into wildly fluctuating seasons and could even move it into and out of a star’s habitable zone where liquid water can exist.
On average, the nearly 1,800 exoplanets discovered to date have orbits almost ten times as elongated as Earth’s, likely resulting in temperature extremes. In some cases, interactions with other planets in the system could explain the stretched-out orbits. But in other systems, especially those with only one planet, the reason for the elliptical orbits can be challenging to explain.
“The fact that the average should be so high is a mystery we want to answer,” said Alan Hulsebus, a doctorate student at Iowa State University and primary author of the paper.
He added:
“Did [the exoplanets] form this way by some unknown mechanism, or were they nudged into those [elliptical] orbits through interactions with another object? Was this a one-time action or something secular? If the latter, is that object still around and can we detect it?”
Hulsebus led a search of the 14 closest planet-hosting stars near Earth for signs of a brown dwarf, a massive object that could potentially shift the orbits of the planets.
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Planets that move around their stars in circular orbits are a better bet for life than those in elongated orbits when it comes to creating habitable climate conditions, according to a new study.
That’s because circular orbits tend to have more stable climates, while an overly elliptical orbit could send a planet into wildly fluctuating seasons and could even move it into and out of a star’s habitable zone where liquid water can exist.
On average, the nearly 1,800 exoplanets discovered to date have orbits almost ten times as elongated as Earth’s, likely resulting in temperature extremes. In some cases, interactions with other planets in the system could explain the stretched-out orbits. But in other systems, especially those with only one planet, the reason for the elliptical orbits can be challenging to explain.
“The fact that the average should be so high is a mystery we want to answer,” said Alan Hulsebus, a doctorate student at Iowa State University and primary author of the paper.
He added:
“Did [the exoplanets] form this way by some unknown mechanism, or were they nudged into those [elliptical] orbits through interactions with another object? Was this a one-time action or something secular? If the latter, is that object still around and can we detect it?”
Hulsebus led a search of the 14 closest planet-hosting stars near Earth for signs of a brown dwarf, a massive object that could potentially shift the orbits of the planets.