RUSENG

December 19, 2018, 08:20 UTC

The solar winter ends in the South of the Sun

Magnetic fields of the new 25th solar cycle in the Southern hemisphere. The photo is taken by the HMI telescope on the satellite SDO. In the Northern hemisphere the magnetic fluxes of the northern magnetic zone are visible.

For several days, in the Southern hemisphere of the Sun, signs of the beginning of a new solar cycle have appeared and been observed. Earlier, about a month ago, similar processes were discovered in the Northern hemisphere. Thus, the transition from the minimum activity of the Sun to its growth phase might have been already launched on a global scale in both, the North and the South of our star, and the Sun decided to enter the new year 2019, being completely renewed. However, the possibility of a noticeable increase in the number of solar flares and spots will keep us waiting for another few months or to a year.

Fluctuation in the solar activity, also known as the 11-year cycle, are associated with changes in the magnetic field of the Sun. At the maximum of the cycle, the magnetic field on the Sun is at its maximum (the excess of magnetic energy that is burnt by our star in the form of flares), while at the minimum of activity the field almost disappears. Unlike the Earth, where the magnetic field is unified and has a planetary character, the Sun has two so-called magnetic belts - one is located in the Northern hemisphere, the other in the Southern. Moreover, if the Earth's magnetic field lines are directed vertically (from South to North), when in the solar magnetic zones, they are located horizontally, parallel to the equator, and engirdle the Sun in a circle.

In fact, since the Sun has two magnetic fields, the question arises of how much they “communicate” with each other or develop independently. In general, it is believed that both zones are formed by a single process - the rotation of the Sun - and for this reason, they cannot completely diverge in their evolution. At the same time, observations show that the solar cycle usually goes differently in the North and in the South - it can be stronger in the same belt for 11 years (this is where the strongest flares will occur in this case), and, be weaker in another, accordingly. The moment of the beginning of the cycle in the Northern and Southern hemispheres may also vary. Like the 24th solar cycle in the past, had the Northern hemisphere more active.

About a month ago, it was in this Northern hemisphere that magnetic fluxes with different direction of the field lines, different from the direction of the 24th cycle, were discovered. These fluxes became the evidence that the process of a new cycle formation has been launched in the North of the Sun and now need only to wait until it begins to unfold in its full force. All this time, in the Southern hemisphere of the Sun, previous direction of the field lines was maintained without any hint of changes. And, on the last weekend, on Sunday the 16th a new magnetic flux of the 25th cycles had surfaced in the Southern hemisphere of the Sun. Although in such cases element of the chance is always possible, as of the present moment, the flux has been in existence for 4 days already, which is an indication of its stability. Taking into account that a similar process was recorded in the North, it is highly likely that this is a beginning of formation of the 25th cycle in the Southern hemisphere, indeed.

Of course, it should be clear that the first signs do not yet speak of the beginning of new cycle on a large-scale, just as the first snow does not mean the beginning of winter, so as the temperature above zero at the beginning of summer. So far, this only indicates that the processes of the formation of the 25th cycle have been launched, and on a global scale, in both hemispheres of the Sun, the North and the South, and, that they are developing according to the traditional scenario as well.