We know that Jupiter is the largest planet in our solar system, but we have rarely observed or heard about ‘Hot Jupiter’, which are giant gaseous exoplanets that are much closer to the stars and their mysteriously decaying orbits around which they orbit.
A new orbital clue reveals the method that reveals how hot Jupiter actually forms and slips in peacefully rather than being violently scattered.
Scientists have observed that hot Jupiters were once cosmic oddities, but how they got so close to their stars has remained a persistent mystery.
Hot Jupiter is the first exoplanet confirmed in 1995: a gigantic world similar in mass to Jupiter, but orbiting its stars for only a few days.
Astronomers have identified more than 4,000 exoplanets, but the science behind their orbital decay was still unknown.
However, scientists now think that these planets originally formed far from their host stars.
According to Science daily, a new approach from researchers in Tokyo breaks this debate by using the time scale of orbital circulation as a diagnostic clue.
Gravitational tides and magnetic fields determine the course of the decay
In the migration scenario, a planet first follows a very elongated path before its orbit becomes circular again as it repeatedly orbits close to its star.
Researchers found that the time it takes for a planet’s orbit to become circular can reveal the path it took, and the amount of time it takes for this circularization depends on several factors, including the planet’s mass, its orbital characteristics and tidal forces.
A number of these planets are also part of multi-planet systems, a configuration that typically disrupts high-eccentricity migration because that process can scatter or eject neighboring planets.
The University of Tokyo researchers have discovered two leading theories that explain the mechanisms involved in the migration of hot Jupiter: gravitational scattering caused by other planets and dynamic interactions with the still-present circumstellar disk.
The new study found that ‘Hot Jupiter’ may have arrived near their stars through turbulent gravitational encounters or slow, steady drift.
To gain further clarity, the team introduced a new method that focuses on the length of time required for high eccentricity migration to occur.
“It opens a new avenue for tidal research and will help observational astronomers find promising targets to observe orbital decay,” says Dr. Craig Duguid, one of the study’s authors and a postdoctoral research fellow at the University of Durham.
During their study, the researchers discovered that a star’s magnetic field plays an important role in shaping the gravitational tides that cause a hot Jupiter’s orbital decay.
The new study from researchers at the University of Tokyo, published in the Journal Identification of nearby Jupiters that arrived via disk migration, evidence of original alignment, preference of close companions and hint of runaway migration, reflects on the importance of how migration is essential to piece together the history of planetary systems.
Scientists report that future studies could provide deeper insight into the origin and evolution of hot Jupiters.
