Can Superflares Occur on Our Sun?

Abstract

Recent observations of solar type stars with the Kepler satellite by Maehara et al. have revealed the existence of superflares (with energy of 10^33 - 10^35 erg) on Sun-like stars, which are similar to our Sun in their surface temperature (5600 K - 6000 K) and slow rotation (rotational period > 10 days). From the statistical analysis of these superflares, it was found that superflares with energy 10^34 erg occur once in 800 years and superflares with 10^35 erg occur once in 5000 years on Sun-like stars. In this paper, we examine whether superflares with energy of 10^33 - 10^35 erg could occur on the present Sun through the use of simple order-of-magnitude estimates based on current ideas relating to the mechanisms of the solar dynamo.

If the magnetic flux is generated by the differential rotation at the base of convection zone as assumed in typical dynamo models, it is possible that the present Sun would generate a large sunspot with total magnetic
flux ~2 x 1023 Mx within one solar cycle period, and lead to superflares with energy of
1034 erg.
On the other hand, it would take ~40 years to store total magnetic flux ~ 1024 Mx for generating 1035 erg superflares. Many questions remain relating to how to store
1024 Mx below the base of convection zone and how to erupt a magnetic flux tube in a short time to create a sunspot with 1024 Mx, which presents a challenge to dynamo
theorists.

Hot Jupiters, however, which have been often argued to be a necessaryingredient for generation of superflares, do not play any essential role on generation of magnetic flux in the star itself, if we consider only magnetic interaction between the star and the hot Jupiter. This seems to be consistent with Maehara et al.’s finding of 148 superflare-generating solar type stars which do not have a hot Jupiter companion.
Altogether, our simple calculations, combined with Maehara et al.’s analysis of superflares on Sun-like stars, show that there is a possibility that superflares of 1034 erg would occur once in 800 years on our present Sun, while it is premature to conclude whether it is possible for 1035 erg superflares to occur on our present Sun on the basis of application of current dynamo theory.

Last Edited by Rain-Man on 12/10/2012 09:10 AM

You can fit nearly one million earths inside our Sun. Just a large flare/cme is huge compared to earth and could be hugely devastating if not for our mag shields.