Sunspots have been observed for over four centuries and the magnetic nature of sunspot cycles has been known for about a century. However, some of its underlying physics still remain elusive. In new research, astronomers at IISER Kolkata discovered a new relationship between the rise rate of the sunspot cycle and the Sun’s magnetic field. Their results indicate that the maximum intensity of solar cycle 25, the ongoing sunspot cycle, is imminent and likely to occur within a year.
Our host star, the Sun, is a dynamic star whose magnetic activity varies across a wide range of time-scales spanning from minutes to millennia and beyond.
The most prominent signature of this variability is captured by the waxing and waning of sunspots — dark, magnetized patches on the Sun’s surface — that repeats almost every 11 years, known as the sunspot cycle.
Sunspot cycles exhibit significant fluctuations in both amplitude and duration that occasionally result in extreme activity phases like solar grand minima and grand maxima.
The Sun’s dynamic activity output influences the entirety of the heliosphere including our home planet by shaping its space environmental conditions and determining the habitability.
Therefore, developing accurate predictive capabilities pertaining to the long-term solar activity is crucial in planning future space missions and safeguarding space-reliant technologies.
“The solar cycle is produced by a dynamo mechanism driven by energy from plasma flows inside the Sun,” said IISER researcher Dibyendu Nandy and colleagues.
“This dynamo mechanism is understood to involve two primary components of the Sun’s magnetic field, one which manifests in the cycle of sunspots and another which manifests in a recycling of the large-scale dipole field of the Sun; the latter is much like the Earth’s magnetic field — stretching from one pole of the Sun to another.”
“With the cycle of sunspots, the Sun’s dipole field is also observed to wax and…
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