Superflares, monstrous explosions from our Sun that have occurred in the past, could wreak havoc on our little world - it technological infrastructure and life forms. Habitually, they have been written off as "unlikely" but this may be premature. From the time of my original paper linking sunspots to solar flares, e.g.
http://adsabs.harvard.edu/full/1983SoPh...88..137A
It’s been known that solar flares are closely correlated with sunspot group evolution and that the intensity of solar flare eruptions is related to the size of sunspot groups, the number of sunspots in groups, and the complexity of the magnetic field. The more complex the structures and magnetic field polarities are, the more likely large solar flares will erupt (See e.g. Greatrix 1963; Zirin & Liggett 1987; Kilcik et al. 2011; Norquist 2011; McCloskey et al. 2016; Eren & Kilcik 2017).
More recently Sammis et al. (2000) found that βγδ groups with an area larger than 1000 millionths of a solar hemisphere (msh) have a 40% probability of producing X1 or larger flares. (Recall βγ denotes a bipolar sunspot group but sufficiently complex that no distinction can be made between opposite polarities. A δ group - magnetic class - indicates a group with umbrae separated by less than 2 degrees within one penumbra, with opposite polarity.)
It has also been found that for βγδ groups exceeding more than 1000 msh in area X4 or larger flares can occur within them. Ternullo et al. (2006) found that spot groups with more than 15 sunspots accompanied by larger area (> 1000 msh), and more complex magnetic field structures (e.g., β, βγ, and βγδ) are more prone to larger M and X class flares.
With larger area sunspots the buildup of vast stores of magnetic free energy (MFE) is also more likely, and Prof. Kazunari Shibata in his paper (‘From Jets to Superflares: Extraordinary Activity of Magnetized Plasmas in the Universe') presented in June of 2020 at the 236th meeting of the American Astronomical Society) showed the MFE can attain energies of 10 35 ergs ( 1028 J) and X100 on the x-ray scale (see lower graphic above). This is applicable to Sun-like stars with effective (surface) temperatures of 5600K- 6000K.
The magnetic energy buildup preceding geo-effective solar flares, paving the way for a flare trigger was first postulated by me (Proceedings of the Second Caribbean Physics Conference, Ed. L.L. Moseley, pp. 1-11.) to account for release of magnetic free energy using:
DE mfe = ¶/ ¶ t {òv B2/2m dV}
= 1/m òv div[(v X B) X B] dV - òv {han | Jms |2 }dV
This also left open an evolutionary increase in spot complexity, spot area and acquisition of MFE via field twisting. In particular, I had noted the potential for vast magnitudes of free energy release if the sunspot area was sufficiently large (> 1500 msh), the magnetic configuration sufficiently complex (i.e. presence of delta spots) and anomalous resistivity ( han ) coincident with marginal stability of current density ( Jms). We know that if anomalous resistivity and
marginal stability are applicable there will be rapid, turbulent fluctuations
with JMS being driven by an external agent, in this case the rotary
footpoint motions. As JMS
approaches the critical threshold value for current density, Jc, associated with the drift velocity Vd (1.2 km/s) a back reaction of the plasma brings Jc
® JMS And so violent release of energy can occur especially for a large magnitude change in flux df/dt
associated with rotary velocity Vq. This will persist until a clear additional
micro-instability (e.g. ion -acoustic)
pushes the system directly into the immediate trigger mode.
Bear in mind solar flares are among the most explosive phenomena in the solar system. They were discovered in 1859 during what's referred to as the landmark "Carrington event". A mammoth solar flare which saw telegraphs catch fire, and auroras seen as far south as the Caribbean. The disruptions proved solar events could impact Earth.
In our own current situation, we've become a more vulnerable society by virtue of constructing mammoth, interlocked power grids which can crash if the right combination of factors is imposed. While we do have high voltage transformers that connect directly to the ground (zero or earth potential) to neutralize power surges from lightning strikes, these don't afford any protection against powerful geo-magnetic currents that are induced in the earth and flow upward into the grid. Then one such mammoth event, say from and X10 flare, could spark calamity. Possibly no electric power for days, maybe longer, over vast swatches of North America.
In addition, if a monster flare hurls a super stream of charged particles along with the CME we could expect adverse effects on all GPS positioning satellites. Bear in mind that GPS, besides providing directions for road users, allows synchronized cell phone conversations, as well as orchestrates air traffic not to mention 'date stamping' most financial transactions and guiding the dynamic positioning of the majority of deep sea oil drilling and gas operations.
The first indication that solar flares could be even more formidable came in 2012, with the arrival of a mega storm 10 to 100 times stronger than the Carrington event that occurred in 775 A.D. Now these phenomena appear to be even more common than we thought: researchers investigating the geochemical annals of Earth’s recent history have now found evidence for two more. One occurred in 7176 B.C., when nomadic hunter-gatherer societies were giving way to agrarian settlements. The other happened in 5259 B.C., as the planet emerged from the last ice age. Both events are thought to have been at least as strong as the one in A.D. 775, and for the past decade scientists have been searching for similarly extreme occurrences.
The Sun's magneto-physics hasn't radically changed over some billions of years. It still goes through a 22 -year polarity to polarity sunspot cycle and an 11 -year average spot maxima to maxima cycle. Sunspots - especially in groups - appear, acquire powerful magnetic fields and have the potential to trigger solar flares. Prof. Shibata's paper showed we cannot take for granted that we can always expect easy to deal with flares and their geo-effective events. Perhaps once in a 500 year or 1,000 year period we may get a superflare and total devastation to all our sophisticated infrastructure, including Elon Musk's Space link satellites.
The energy maximum erupting itself is still limited by the amount of magnetic free energy in the CME-releasing region. So this is comforting to know, but that knowledge doesn't release us from trying for forecast when such impacting events could affect us. Hence, the urgent need for accurate space weather forecasts.
For the “solar maximum,” which is estimated to occur in July next year (give or take 3 months), NASA and NOAA forecasters are anticipating about 115 sunspots per month. But a pair of researchers — Scott McIntosh, deputy director of the National Center for Atmospheric Research, and Bob Leamon, a researcher at the University of Maryland Baltimore County and NASA Goddard — predict twice as many. No superflares are forecast but we have to see how active that new cycles is and how many very large and complex spots and spot groups occur. If any are detected with areas over 2,500 msh, and of the δ magnetic class, watch out.
See Also:
New Solar Research Confirms Why Delta Sunspots Are More Flare Worthy Than Other Magnetic Classes
And:
And:
Solar Max Peak Expected To Be Earlier & More Violent Than Originally Forecast
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