Triggering the Birth of New Cycle's Sunspots by Solar Tsunami

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Monday, February 18, 2019

We demonstrate a novel physical mechanism, namely, that a “solar tsunami” occurring in the Sun’s interior shear-fluid layer can trigger new cycle’s magnetic flux emergence at high latitudes, a few weeks after the cessation of old cycle’s flux emergence near the equator.

Graphic image showing six snapshots of global tachocline fluid top surface deformations
Six snapshots of global tachocline fluid top surface deformations are presented in approximately 4 days interval to show the trigerring and development of tsunami, which after reaching the mid-latitudes, lift the weak (nonbuoyant) toroidal bands (white tubes at mid-latitudes) to help erupt as sunspots at solar surface in approximately a couple of weeks since the cessation of the old cycle.

This tsunami is excited at the equator when magnetic dams, created by the oppositely-directed old cycle’s toroidal field in North and South hemispheres, break due to mutual annihilation ofq toroidal flux there. The fluid supported by these dams rushes to the equator; the surplus of fluid cannot be contained there, so it reflects back towards high latitudes, causing a tsunami. This tsunami propagates poleward at a speed of ~300m/s until it encounters the new cycle’s spot-producing toroidal fields in mid-latitudes, where it perturbs the fields, triggering their surface-eruption in the form of new cycle spots. A new sunspot cycle is preceded for several years by other forms of high-latitude magnetic activity, such as coronal bright points and ephemeral regions, until the tsunami causes the birth of new cycle’s spots. The next tsunami is due by 2020, portending the start of intense ‘space weather’ that can adversely impact the Earth.

Publication Name: Nature Scientific Reports

First HAO Author's Name: Mausumi Dikpati