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Home , Carrington event

EXTREME SOLAR EVENTS The distribution of flare energies for the and Sun-like stars

Karel Schrijver Jürg Beer Urs Baltensperger Ed Cliver Lockheed Martin STAR Labs Manuel Güdel Lockheed Martin STAR Labs Hugh Hudson Konstantin Herbst Jozef Masarik Ken McCracken Rachel Osten Thomas Peter David Soderblom Ilya Usoskin Eric Wolff

Karel Schrijver 1 Chameleon behavior of solar storms

l GOES class provides a very uncertain measure of the energy in a solar coronal storm event.

l Example: large scatter in event peak brightness as function of wavelength.

Aschwanden et al. (2014, SPh)

Karel Schrijver 2 Chameleon behavior of solar storms

l GOES class provides a very uncertain measure of the energy in a solar coronal storm event.

l Example: GOES classes for an active-region Fe XVI Fe XVI flare and quiet-Sun filament eruption differ by factor of ~250 for comparable ‘bolometric’ energies in the X-ray/(E) UV domain. Fe IX Fe IX

Karel Schrijver 3 Superposed-epoch light curves for solar flares visible E/XUV

The bulk of the energy X rays X is emitted where it is hardest to measure!

Flare light curves averaged over 2100 flares (from X17.2 to C4) in various spectral ranges. From Kretzschmar (2011)

Karel Schrijver 4 Flare energy: mostly WL and kinetic

Est. non-potential

Modified after Emslie et al. (2012): values for X3, X3, X4, X7, X8, X10 flares.

Karel Schrijver 5 Solar flare statistics

Ebol (Joules) Combining solar EUV to X- 1018 1020 1022 1024 1026 1028 1030 ray data for 39 years of GOES 1010 monitoring of solar activity, Sun: EUV combined with ~2 decades of

EUV observing. Sun: SXR 105

Sun: X-rays

100 ) (per hemisphere per year) bol

f(>E ? -5 10 Sun?

1024 1026 1028 1030 1032 1034 1036 1038

Ebol (ergs)

Karel Schrijver 6 Observed spot group areas: no cutoff (yet)?

“On the size distribution of groups in the Greenwich sunspot record 1874-1976”, Baumann & Solanki (2005).

Karel Schrijver 7 Powering superflares

Aulanier et al. (2013, A&A 549, 66)

Karel Schrijver 8 Powering superflares

Aulanier et al. (2013, A&A 549, 66)

Karel Schrijver 8 Powering superflares

Aulanier et al. (2013, A&A 549, 66)

The largest sunspot group ever reported since the end of the nineteenth century, as observed in April 5, 1947 in Ca II K2v by the Meudon spectroheliograph.

Karel Schrijver 8 Powering superflares

Aulanier et al. (2013, A&A 549, 66)

The largest sunspot group ever reported since the end of the nineteenth century, as observed in April 5, 1947 in Ca II K2v by the Meudon spectroheliograph.

Karel Schrijver 9 Powering superflares

Aulanier et al. (2013, A&A 549, 66)

The largest sunspot group ever reported since the end of the nineteenth century, as observed in April 5, 1947 in Ca II K2v by the Meudon spectroheliograph.

Karel Schrijver 9 Powering superflares

Aulanier et al. (2013, A&A 549, 66)

The largest sunspot group ever reported since the end of the nineteenth century, as observed in April 5, 1947 in Ca II K2v by the Meudon spectroheliograph.

Karel Schrijver 9 Powering superflares

Aulanier et al. (2013, A&A 549, 66)

The largest sunspot group ever reported since the end of the nineteenth century, as observed in April 5, 1947 in Ca ii K1v by the Meudon spectroheliograph.

Karel Schrijver 10 Powering superflares

Aulanier et al. (2013, A&A 549, 66)

The largest sunspot group ever reported since the end of the nineteenth century, as observed on in 1128/12/08,April 5, 1947 in Ca ii K1v by the Meudon spectroheliograph.by John, of Worcester

Karel Schrijver 10 Solar flare statistics

Ebol (Joules) Combining solar EUV to X- 1018 1020 1022 1024 1026 1028 1030 ray data for 39 years of GOES 1010 monitoring of solar activity, Sun: EUV combined with ~2 decades of

EUV observing. Sun: SXR 105

Sun: X-rays

100 ) (per hemisphere per year) bol

f(>E ? -5 10 Sun? Aulanier Aulanier et al. (2013)

1024 1026 1028 1030 1032 1034 1036 1038

Ebol (ergs)

Karel Schrijver 11 Studying flares by proxies?

Karel Schrijver 12 Pre-historic* records of solar activity *Before ~1950 Pre-historic* records of solar activity *Before ~1950 Solar cosmic rays

Stratospheric NO3 10Be, 14C, ... SEPs

SEPs Flare Ice cores: chemicals, radionuclides Solar energetic particles (SEPs)

SEP statistic can be obtained from:

• Spacecraft particle instruments and ground-based neutron monitors;

• Chemical signatures (NO3 in ice)

• Radionuclides in biosphere, ice, rocks (Earth, Moon), meteorites. Solar energetic particles (SEPs)

SEP statistic can be obtained from:

• Spacecraft particle instruments and ground-based neutron monitors;

• Chemical signatures (NO3 in ice)

• Radionuclides in biosphere, ice, rocks (Earth, Moon), meteorites. Solar energetic particles (SEPs)

SEP statistic can be obtained from:

• Spacecraft particle instruments and ground-based neutron monitors;

• Chemical signatures (NO3 in ice)

• Radionuclides in biosphere, ice, rocks (Earth, Moon), meteorites. Solar energetic particles (SEPs)

SEP statistic can be obtained from:

• Spacecraft particle instruments and ground-based neutron monitors;

Once per century

• Chemical signatures (NO3 in ice) Once per millenium

• Radionuclides in biosphere, ice, rocks (Earth, Moon), meteorites. Solar energetic particles (SEPs)

SEP statistic can be obtained from:

• Spacecraft particle instruments and ground-based neutron monitors; Records since ~1950s; too short Once per century

• Chemical signatures (NO3 in ice) Once per millenium atmospheric chemists & glaciologists argued that pathways are improbable and that there is too much source confusion • Radionuclides in biosphere, ice, rocks (Earth, Moon), meteorites.

Lunar rocks & meteorites: cumulative dose only. Biosphere: washes out signal. Ice: limited resolution (~3y) on background of galactic cosmic rays. Lunar radionuclides

Table from Kovaltsov & Usoskin; 2014, Solar Physics, Vol. 289, pp.211-220

Karel Schrijver 15 Lunar & terrestrial radionuclides

Figure from Kovaltsov & Usoskin; 2014, Solar Physics, Vol. 289, pp.211-220

Karel Schrijver 16 Solar-stellar flaring Hugh Hudson’s cartoon archive: http://solarmuri.ssl.berkeley.edu/~hhudson/cartoons/

Schrijver, C., "Driving major solar flares and eruptions: A review" ASR 43, 739 (2009). Flare: • definition/stellar: a sudden, temporary brightening • conceptually/solar: a conversion of EM field energy into kinetic energy, resulting in photons + associated phenomena Solar-stellar comparison possible for infrequent largest solar flares, generally with non-overlapping wavelength ranges.

Karel Schrijver 17 Courtesy: Rachel Osten

Karel Schrijver 18 Stellar flares: XUV

Audard et al. (2000)

Karel Schrijver 19 Visible-light flaring on stars

Kepler light curves

Added note: with 4 arcsec/pixel, source confusion is likely in some cases. Kitze et al. (2014) find evidence for one such case, but Notsu et al. (2013) not for the slowly-rotating stars shown in later diagrams (and in Schrijver and Beer, 2014).

Karel Schrijver 20 Visible-light flaring on stars Kepler data

Notsu et al. (2013, ApJ 771, 127) Solar rotation period

See Nogami et al. (2014; arXiv) on spectroscopic studies of two superflaring Sun-like stars.

Karel Schrijver 21 Powering superflares

Notsu et al. (2013, ApJ 771, 127) Aulanier et al. (2013, A&A 549, 66)

Karel Schrijver 22 Powering superflares

Notsu et al. (2013, ApJ 771, 127) Aulanier et al. (2013, A&A 549, 66)

????????

Karel Schrijver 22 Extreme solar flares

Ebol (Joules) 1018 1020 1022 1024 1026 1028 1030 1010

Sun: EUV

Sun: SXR 105

Sun: X-rays

100 ) (per hemisphere per year) bol f(>E -5 10 Sun?

1024 1026 1028 1030 1032 1034 1036 1038

Ebol (ergs)

Karel Schrijver 23 Extreme solar flares

Ebol (Joules) 1018 1020 1022 1024 1026 1028 1030 Maximum for cool stars 10 36 10 in general: ~3 10 ergs. Sun: EUV

Sun: SXR 105

Sun: X-rays

100 ) (per hemisphere per year) bol f(>E -5 10 Sun? Stellar max. 1024 1026 1028 1030 1032 1034 1036 1038

Ebol (ergs)

Karel Schrijver 24 Extreme solar flares

Ebol (Joules) 1018 1020 1022 1024 1026 1028 1030 Maximum for cool stars 10 36 10 in general: ~3 10 ergs. Sun: EUV

Kepler observations Sun: SXR suggest continuation up 105 to at least ~5 1035 ergs.

Sun: X-rays

100 ) (per hemisphere per year) bol Kepler: Prot>25d f(>E -5 10 Sun? Max. Sun- Stellar like stars max. 1024 1026 1028 1030 1032 1034 1036 1038

Ebol (ergs)

Karel Schrijver 25 Extreme solar flares

Ebol (Joules) 1018 1020 1022 1024 1026 1028 1030 Maximum for cool stars 10 36 10 in general: ~3 10 ergs. Sun: EUV

Kepler observations Sun: SXR suggest continuation up 105 to at least ~5 1035 ergs.

Sun: X-rays But the frequency scaling k Cet, 1995-2.08 k Cet, 1994-2.08 0 with more active stars 10 EK Dra-3.60 fails. ) (per hemisphere per year) bol Kepler: Prot>25d f(>E -5 10 Sun? Max. Sun- Stellar like stars max. 1024 1026 1028 1030 1032 1034 1036 1038

Ebol (ergs)

Karel Schrijver 26 Extreme solar flares

Ebol (Joules) 1018 1020 1022 1024 1026 1028 1030 Maximum for cool stars 10 36 10 in general: ~3 10 ergs. Sun: EUV

Kepler observations Sun: SXR suggest continuation up 105 to at least ~5 1035 ergs.

Sun: X-rays But the frequency scaling k Cet, 1995-2.08 k Cet, 1994-2.08 0 with more active stars 10 EK Dra-3.60 fails. ) (per hemisphere per year)

bol Kepler: P >25d Need to add more stellar rot f(>E -5 observing time, improve 10 Sun? Max. Sun- Stellar understanding of energy like stars max. distributions, and wait ... 1024 1026 1028 1030 1032 1034 1036 1038

Ebol (ergs)

Karel Schrijver 27 Extreme solar flares

Ebol (Joules) 1018 1020 1022 1024 1026 1028 1030 Maximum for cool stars 10 36 10 in general: ~3 10 ergs. Sun: EUV

Kepler observations Sun: SXR suggest continuation up 105 35 Estimated fluence needed to at least ~5 10 ergs. to create the 774-775AD 14 Sun: X-rays C spike (according to But the frequency scaling Cliver et al., 2014) k Cet, 1995-2.08 k Cet, 1994-2.08 0 with more active stars 10 EK Dra-3.60 fails. ) (per hemisphere per year)

bol Kepler: P >25d Need to add more stellar rot f(>E -5 observing time, improve 10 Sun? Max. Sun- Stellar understanding of energy like stars max. distributions, and wait ... 1024 1026 1028 1030 1032 1034 1036 1038

Ebol (ergs)

Karel Schrijver 27 Lunar radionuclides

Figure from Kovaltsov & Usoskin; 2014, Solar Physics, Vol. 289, pp.211-220

Karel Schrijver 28 Lunar radionuclides

Estimated fluence needed to create the 774-775AD 14C spike (according to Cliver et al., 2014)

Figure from Kovaltsov & Usoskin; 2014, Solar Physics, Vol. 289, pp.211-220

Karel Schrijver 28 Lunar radionuclides

Estimated fluence needed to create the 774-775AD 14C spike (according to Cliver et al., 2014)

(according to Usoskin et al., 2013)

Figure from Kovaltsov & Usoskin; 2014, Solar Physics, Vol. 289, pp.211-220

Karel Schrijver 28 Lunar radionuclides

Estimated fluence needed to create the 774-775AD 14C spike (according to Cliver et al., 2014)

(according to Usoskin et al., 2013)

Figure from Kovaltsov & Usoskin; 2014, Solar Physics, Vol. 289, pp.211-220

Karel Schrijver 28 Karel Schrijver 29 Karel Schrijver 29 The worst

Karel Schrijver 30 The worst space weather

Stellar data reveal that some space weather can be much more severe than what we have recently experienced: • Solar flares may reach energies up to 100-300 times above those observed in the past four decades.

Lunar and terrestrial radionuclide and theory suggest that different types of extreme space weather do not serve as mutual proxies: • Energetic particle storm intensities likely saturate at a few times the space- age maximum. • Geomagnetic storms may never exceed twice the strength of the powerful 1859 Carrington event [if focusing on Dst – but is that the right thing to do?].

All these potential extremes exceed the levels to which modern technologies, connected in a network of growing complexity, have been exposed.

Karel Schrijver 30 The worst space weather Stellar observations are essential to establish the largest possible flare from the Sun ... but can we be confident that stars are “Sun-like”?

Radio-nuclide studies of lunar rocks and terrestrial ice and biosphere records need to be re-analyzed and extended in time and increased in signal-to-noise contrast ... but how do ‘extreme’ SEP events map to extreme flares?

Models are needed to know the worst possible geomagnetic storm ... or are there other ways to establish extreme GMD limits?

But the bottom line is: yes, it can get worse than we have experienced to date! Can we set an upper limit, or merely a smooth frequency distribution?

Karel Schrijver 31 The worst space weather Stellar observations are essential to establish the largest possible flare from the Sun ... but can we be confident that stars are “Sun-like”?

Radio-nuclide studies of lunar rocks and terrestrial ice and biosphere records need to be re-analyzed and extended in time and increased in signal-to-noise contrast ... but how do ‘extreme’ SEP events map to extreme flares?

Models are needed to know the worst possible geomagnetic storm ... or are there other ways to establish extreme GMD limits?

But the bottom line is: yes, it can get worse than we have experienced to date! Can we set an upper limit, or merely a smooth frequency distribution? All these potential extremes exceed the levels to which modern technologies, connected in a network of growing complexity, have been exposed.

Karel Schrijver 31 Karel Schrijver 32