Study: 'Hot Jupiter' exoplanets formed extremely rapidly

"This discovery suggests that hot Jupiters may be extremely young," CNRS researchers said.

By Brooks Hays
A rendering of a hot Jupiter exoplanet. Photo by NASA
A rendering of a hot Jupiter exoplanet. Photo by NASA

PARIS, Sept. 16 (UPI) -- For years, astronomers have been stumped by a rare type of exoplanet known as "hot Jupiters." Hot Jupiters are gas giants which orbit unusually close to their stars.

Scientists have theorized that hot Jupiters form in the outer reaches of their solar systems and drift inward toward their host star -- the opposite of the trajectory of the real Jupiter and most other gas giants. It's their arrival near their stars that makes them hot and causes their gas to expand to such a large size.


Until now, scientists weren't sure what stage of the exoplanet's life cycle a hot Jupiter occupied. Did hot Jupiters assume their inner orbits late in the evolution of their solar system, or early?

New evidence suggests hot Jupiters migrate inward earlier rather than later. According to a new study published in the journal Monthly Notices of the Royal Astronomical Society, their formation and repositioning happens within the space a few million years (chump change in cosmic time).

In analyzing the disturbances picked up in the electromagnetic output of a young star, V830 Tau, an international team of astrophysicists traced the path of a hot Jupiter.


The team was led by Jean-François Donati, a scientist with the French National Center for Scientific Research (CNRS).

"This discovery suggests that hot Jupiters may be extremely young and potentially far more frequently found around stars in formation than around mature stars like the Sun," CNRS wrote in a press release.

In addition to shedding light on the formation of hot Jupiters, the new study confirms the effectiveness of a new exoplanet-discovery method inspired by medical imaging techniques. By scanning the topology of a star's magnetic field as it rotates, plotting its light and dark spots, researchers are able to pick out which perturbations are naturally occurring and which are exoplanets.

Researchers say the new method will "make it possible to explore the formation of stars and exoplanets in even greater detail."

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