The standard flare model in three dimensions II: upper limit on solar flare energy
By G. Aulanier, P. Démoulin, C. Schrijver, M. Janvier, Etienne Pariat, Brigitte Schmieder. 2012
195 citations recorded by the source corpus.
Context. Solar flares strongly affect the Sun’s atmosphere as well as the Earth’s environment. Quantifying the maximum possible energy of solar flares of the present-day Sun, if any, is thus a key question in heliophysics. Aims. The largest solar flares observed over the past few decades have reached energies of a few times 10 32 ergs, possibly up to 10 33 ergs. Flares in active Sun-like stars reach up to about 10 36 ergs. In the absence of direct observations of solar flares within this range, complementary methods of investigation are needed to assess the probability of solar flares beyond those in the observational record. Methods. Using historical reports for sunspot and solar active region properties in the photosphere, we scaled to observed solar values a realistic dimensionless 3D MHD simulation for eruptive flares, which originate from a highly sheared bipole. This enabled us to calculate the magnetic fluxes and flare energies in the model in a wide paramater space. Results. Firstly, commonly observed solar conditions lead to modeled magnetic fluxes and flare energies that are comparable to those estimated from observations. Secondly, we evaluate from observations that 30% of the area of sunspot groups are typically involved in flares. This is related to the strong fragmentation of these groups, which naturally results from sub-photospheric convection. When the model is scaled to 30% of the area of the largest sunspot group ever reported, with its peak magnetic field being set to the strongest value ever measured in a sunspot, it produces a flare with a maximum energy of � 6 × 10 33 ergs. Conclusions. The results of the model suggest that the Sun is able to produce flares up to about six times as energetic in total solar irradiance (TSI) fluence as the strongest directly-observed flare from Nov 4, 2003. Sunspot groups larger than historically reported would yield superflares for spot pairs that would exceed tens of degrees in extent. We thus conjecture that superflare-productive Sun-like stars should have a much stronger dynamo than in the Sun.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/863b54c83b8cc2dc4653e2c989d7f7e561c5664c
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In Astronomy and Astrophysics
- G. Aulanier
- Etienne Pariat
- Brigitte Schmieder
- P. Démoulin
- M. Janvier
- C. Schrijver
- E. Cliver
- V. Bommier
Citations in the corpus
- The 1859 space weather event revisited: limits of extreme activity (2013, methodology): “(2012) and Aulanier et al. (2013) determined the peak attainable bolometric energy based on the observed maximum areas and magnetic field strengths of solar active regions and an estimated magnetic energy conversion efficiency. Schrijver et al. (2012) suggested a maximum radiative energy release of ”
- MAGNETIC PROPERTIES OF SOLAR ACTIVE REGIONS THAT GOVERN LARGE SOLAR FLARES AND ERUPTIONS (2016, background): “The largest sunspot group since the nineteenth century, RGO 14886, recorded a maximum spot area of 6132 MSH on 1947 April 8 (see Figure3 of Aulanier et al. 2013).”
- ELECTRIC CURRENTS IN FLARE RIBBONS: OBSERVATIONS AND THREE-DIMENSIONAL STANDARD MODEL (2014, background): “This model also quantifies the energy release in flares on the basis of the spatial size and magnetic flux of active regions (Aulanier et al. 2013).”