In the realm of solar and stellar physics, researchers Vindya Vashishth and Bidya Binay Karak from the Indian Institute of Astrophysics have been exploring the workings of the Babcock-Leighton dynamo, a process that helps explain the solar magnetic cycle. Their recent study, published in the journal Monthly Notices of the Royal Astronomical Society, investigates whether this dynamo mechanism can operate in rapidly rotating stars, similar to our Sun but spinning much faster.
The Babcock-Leighton dynamo works by generating a poloidal magnetic field through the decay and dispersal of tilted bipolar magnetic regions (BMRs). In rapidly rotating stars, these BMRs are expected to emerge at high latitudes, which are less effective in generating the poloidal field due to poor cross-equatorial cancellation. This raises questions about the operation of the Babcock-Leighton dynamo in such stars.
To address this, Vashishth and Karak used a 3D kinematic dynamo model called STABLE. They conducted a series of dynamo simulations for rapidly rotating stars, exploring four different cases of spot deposition, each based on a different assumption about the rise of toroidal flux tubes. These cases included radial rise, parallel rise to the rotation axis, parallel rise combined with an increase in Joy’s law slope with the stellar rotation rate, and increasing time delay and spot size.
The researchers found that cyclic magnetic fields were present in all cases except for the fourth case in the 1-day rotating star, where the magnetic field was irregular. For the parallel-rise cases, the magnetic field became quadrupolar, while for all other cases, it remained dipolar. This work demonstrates that the Babcock-Leighton dynamo may indeed operate in rapidly rotating stars, even with starspots appearing at higher latitudes.
For the energy industry, understanding the magnetic dynamics of stars can have practical applications. Solar and stellar activity can impact space weather, which in turn can affect satellite operations, power grids, and communication systems. By improving our understanding of the magnetic cycles of stars, we can better predict and mitigate these impacts, ensuring the reliable operation of energy infrastructure.
This article is based on research available at arXiv.