A recent study led by Durham University researchers has discovered a new mechanism that could solve the long-standing mystery of the disruption of planetary orbits around stars similar to our Sun. Astrophysics Journal Letters The study suggests that stellar magnetic fields are critical in dispersing the gravitational tides responsible for the orbital disruption of “hot Jupiter” exoplanets.

Hot Jupiters are massive, gaseous Jupiter-like planets that orbit extremely close to their parent stars, taking only a few days to complete a revolution. This proximity subjects both planet and star to powerful gravitational tides that transfer orbital energy, causing the planets to slowly spiral inward over billions of years until they eventually disappear.

Difficulties with modern theories

Current tidal theories cannot fully explain the orbital perturbation observed in the WASP-12b system, a hot Jupiter whose orbit is fading and will send it towards WASP-12’s parent star in a few million years. According to the research team, which includes scientists from Durham, the University of Leeds and Northwestern University, the strong magnetic fields inside some Sun-like stars could be very effective in dispersing gravitational fluctuations from hot Jupiter planets.

Tides create internal waves inside stars. When these waves encounter magnetic fields, they are transformed into different types of magnetic waves that propagate outward and eventually die out.

Commenting on the findings, Dr Craig Daguid, lead author of the study from Durham University, said: “This new mechanism has far-reaching implications, particularly for the survival of short-period planets and hot Jupiters. It will open up a new way to study tides and help observational astronomers find promising targets for observing orbital perturbations. It’s also very exciting that this new mechanism could be tested with observations in our lifetime.”

The results of the study suggest that some nearby stars could be good targets for searching for additional hot-Jupiter planets in decaying orbits. If found, they could provide more evidence of how magnetic fields affect the tides from these alien worlds. The study could also reveal where tidal energy dissipated within the star goes.