A 'Failed Hot Jupiter' With a Weird Orbit Could Explain How Gas Giants Form

Scientists have confirmed the existence of an "extraordinary" hot Jupiter-type planet that may help explain how the gas giants of our own solar system were formed.

The planet, named Kepler-1704b, could also explain how certain planets end up orbiting their host stars in non-circular ways.

Researchers have dubbed Kepler-1704b a "failed hot Jupiter" that orbits its host star, Kepler-1704, once every 989 days or so. It is around 2,690 light years away from Earth.

The planet has a mass of around 4.15 times that of Jupiter but has a similar radius.

Hot Jupiter-type planets are nothing new. They have been discovered before, orbiting close to their host stars and sometimes exhibiting extreme and hostile environments.

But what makes Kepler-1704b interesting to researchers is how it orbits its star.

While many planets orbit their stars in a rough circle, others orbit their planet in an oval-shape. The shape of a planet's orbit is known as its eccentricity, given by the unit e.

An eccentricity of 0 is a perfectly circular orbit, and an eccentricity of 1 means the orbit is no longer circular or even an orbit at all—the object would pass by its star and shoot off into space, never to return.

Earth's orbital eccentricity, for example, is 0.017, so is very nearly circular. The eccentricity of Kepler-1704b is 0.92, meaning that at certain points in its orbit it is very close to its star and at others it is very far away.

Researchers think Kepler-1704b sometimes comes as close as 14,873,000 miles away from its host star—many times closer than Earth does to the sun. But at its furthest point, the gas giant can be as far as 362,500,000 miles away.

The research team's findings have been presented in a pre-print paper, published July 16, and are due to be published in the Astronomical Journal. The study was led by Paul A. Dalba, a planetary scientist at the University of California Riverside.

Kepler-1704b was thought to exist before now because scientists spotted a brief dimming of its star—a tell-tale sign that a planet had passed in front of it.

"However, transit signals have many false-positive explanations, especially those from cold, gas giant planets like this one," Dalba told Newsweek.

"So, Kepler-1704 b got stuck at the 'planet candidate' stage. Now, after nearly a decade of follow-up data collection, my colleagues and I were finally able to confirm that it is a genuine exoplanet with a wildly eccentric orbit."

In the study, the team said giant exoplanets with eccentric orbits are "valuable laboratories" for testing theories of how planets migrate to such orbits in the first place.

The study states: "Kepler-1704b is an extraordinary system owing to its high eccentricity and transiting geometry.

"Continued characterization of the Kepler-1704 system promises to refine theories explaining the formation of hot Jupiters and cool giant planets like those in the solar system."

Until now Kepler-1704b and its host star were known as KOI-375.01 and KOI-375 respectively.

The existence of Kepler-1704b was confirmed as part of the Giant Outer Transiting Exoplanet Mass survey (GOT 'EM).

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A stock image shows an illustration of Jupiter. Scientist have confirmed the existence of a Jupiter-like planet, Kepler-1704b. Getty Images