Recovery from Maunder-like Grand Minima in a Babcock–Leighton Solar Dynamo Model

Tuesday, September 4, 2018

The Sun occasionally goes through Maunder-like extended grand minima when its magnetic activity drops considerably from the normal activity level for several decades. Many possible theories have been proposed to explain the origin of these minima.

Temporal variation of the smoothed sunspot number image
Temporal variation of the smoothed sunspot number from a 13,000-year of dynamo simulation with tilt angle scatter around Joy's law. Blue shaded regions below the horizontal line represent the grand minima. (b) Monthly smoothed (with boxcar average of 3-month width) spot number (black/red: north/south) shown only for a selected 1600-year interval. Vertical dashed lines indicate the time-window of a typical grand minimum.

However, how the Sun managed to recover from such inactive phases every time is even more enigmatic. The Babcock-Leighton type dynamos, which are successful in explaining many features of the solar cycle remarkably well, are not expected to operate during grand minima due to the lack of a sufficient number of sunspots. In this publication, we explore the question of how the Sun could recover from grand minima through the Babcock–Leighton dynamo. In our three-dimensional dynamo model, grand minima are produced spontaneously as a result of random variations in the tilt angle of emerging active regions. We find that the Babcock–Leighton process can still operate during grand minima with only a minimal number of sunspots, and that the model can emerge from such phases without the need for an additional generation mechanism for the poloidal field.

Publication Name: Astrophysical Journal

First HAO Author's Name: Bidya Binay Karak