An international team of astronomers has discovered the key role of stellar magnetic fields
Scientists from Durham University have conducted research that may solve the long-standing mystery of the decay of the orbits of exoplanets like «hot Jupiters» orbiting near their stars. The work, published in The Astrophysical Journal Letters, suggests that stellar magnetic fields play a key role in dissipating the powerful gravitational tides responsible for the gradual destruction of such orbits.
«Hot Jupiters» — These are massive gas giants, similar to Jupiter in the solar system, but orbiting their stars in extremely close orbits, completing one revolution in just a few days. This proximity exposes both planet and star to powerful gravitational tides that transfer orbital energy over billions of years, causing the planets to slowly approach the stars until they are eventually consumed.
Current theories cannot fully explain the observed decay of the orbit of the exoplanet WASP-12b — «hot Jupiter», whose orbit will collapse in a few million years, and it will fall onto its parent star WASP-12.
Strong magnetic fields inside some sun-like stars can be very effective at dissipating gravitational tides from «hot Jupiters», according to an international research team from the Universities of Durham, Leeds and Northwestern University. < /p>
«Tids create ripples inside stars. When these waves encounter magnetic fields, they are converted into different types of magnetic waves that propagate outward and eventually disappear— explains lead author of the study Dr. Craig Duguid from the Institute for Computational Cosmology at Durham University.
He notes the far-reaching consequences of this mechanism for the survival of short-period planets, especially “hot Jupiters.” The discovery also opens up new opportunities for tidal research and will help observational astronomers find promising targets for studying orbital decay.
«It is very interesting that this new mechanism can be tested by observation in our lifetime», — Dr. Duguid adds.
The results show that some nearby stars may be good targets for searching for «hot Jupiters» in decaying orbits. Finding them could provide more evidence of how magnetic fields affect the tides of these planets. In addition, the study may clarify where tidal energy is dissipated inside stars.