Solar tsunami can trigger the sunspot cycle

Mains Paper 1: Geography | Salient features of World’s Physical Geography

From UPSC perspective, the following things are important:

Prelims level: Sunspots, Solar Tsunami

Mains level: Impact of Sunspots on mankind as a whole

A group of solar physicists suggests that a “solar tsunami” is at work that triggers the new sunspot cycle, after the old one ends.

Solar Dynamo

It is believed that the “solar dynamo” a naturally occurring generator which produces electric and magnetic fields in the sun is linked to the production of sunspots.
What kick-starts the 11-year sunspot cycle is not known.
The extreme temperature and pressure conditions that prevail some 20,000 km below the sun’s surface cause its material to form plasma consisting primarily of hydrogen and helium in a highly ionised state.
The plasma is confined with huge magnetic fields inside the sun.

What is Solar Tsunami?

The sun’s magnetic field, from which sunspots get generated, wraps around the sun in the east-west direction.
These magnetic fields behave like rubber bands on a polished sphere. They tend to slip towards the poles.
Holding these fields in their place requires that there is extra mass (plasma mass) pushing at the bands from higher latitudes.
Thus, a magnetic dam is formed which is storing a big mass of plasma.
At the end of a solar cycle, this magnetic dam can break, releasing huge amounts of plasma cascading like a tsunami towards the poles.
These tsunami waves travel at high speeds of about 1,000 km per hour carrying excess plasma to the mid-latitudes.
There they give rise to magnetic flux eruptions.
These are seen as the bright patches that signal the start of the next cycle of sunspots.

What are Sunspots?

Sunspots are temporary phenomena on the Sun’s photosphere that appear as spots darker than the surrounding areas.
They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection.
Sunspots usually appear in pairs of opposite magnetic polarity.

Why study them?

The solar cycle and sunspot activity are intimately connected with space weather.
The model provides a sound physical mechanism supporting why we should expect the next sunspot cycle 25 to begin in the year 2020.
This is again followed by a strong increase in space weather shortly after the trigger of a series of new sunspots in that year.