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The Sun and Life on PlanetsHinodeX-ray Sun in 2007X-ray Sun in 2012Saku TsunetaInstitute of Space and Astronautical Science (ISAS)Japan Aerospace Exploration Agency (JAXA)2016 September 5 Science of the Cosmos, Science in the CosmosBBVA Foundation, Madrid

Todays talkSunspots and magnetic fields of our SunIs the Sun about to run out of sunspots?Global warming or cooling?Planetary magnetic fields: a protector for lifeSuper flares: hazards for life and civilization Could a second Earth harbor life?

Sunspot

EUV ImagingSpectrometerEISObserve plasma temperature & motionSolar Optical TelescopeSOTHigh spatial-resolutionmagnetic field observationsX-ray Telescope XRT1-10MK X-ray corona

How is the magnetic field created? is the corona heated? do explosions (solar flares) occur? is the supersonic solar wind accelerated?

3 well-coordinated advanced telescopes.Orbit: Polar Sun SynchronousJAXA-NASA-UK-ESA Hinode

Closer and closer to the sun, you begin to see granulation(convection cell)

Closer and closer to the sun, you begin to see granulation(convection cell)

Closer and closer to the sun, you begin to see granulation(convection cell)

Closer and closer to the sun, you begin to see granulation(convection cell)

Closer and closer to the sun, you begin to see granulation(convection cell)

Closer and closer to the sun, you begin to see granulation(convection cell)

JapanSunspot!

Sunspots have strong magnetic fields

Magnetic field lineX-ray image of the Sun

How strong is the magnetic field of a sunspot?Sunspot magnetic field is 1000-3000 Gauss. Magnetic field inside the Sun is about 100,000 Gauss!

N S

North poleSouth pole

NS

NS

Earth: 0.5 Gauss Milky Way: 0.000001 (one millionth) GaussBar magnet2500 Gaussmagnetic wall plaster800 GaussS

Rotation of the SunConvection inside the SunOrigin of Magnetic fields

KineticEnergyMagneticEnergyDynamoCoronal heatingSolar flaresreconnectionwaves

Magnetic fieldsemanating frominside the Sun

Photosphere and dynamic chromosphereQuiet Photosphere(430nm)Active Chromosphere(396nm)Sunspot

Different outlook:Corona seen in X-rays1-10MK

Prominence sustained by magnetic fields

First observation of solar polar region by Hinode

How can we see the polar region?Suns axis is tilted 7degree from the Earths orbital planeIn March, we can glimpse the Solar South pole.September is a good season to observe North pole.7 degree

Earth location in SeptemberEarth location in MarchOrbital planeof the Earth

Rotation axis

Observing region inSeptemberObserving Region in March

Reversal of polar field every 11 years

Year 1997

Year 2008Magnetic map (ESA SOHO)White/blueplus polarityBlack/orange : minus polarity

+-

+-

Magnetic field around the Suns poles

Sep. 2012 Sep. 2013 Sep. 2014 Sep.2015Mar. 2013 Mar. 2014 Mar. 2015 Mar.2016North Polar RegionSouth Polar Region

Year 2008Year 2012-13At maximum sunspots, the polar fields were thought to flip together.But, Hinode found that the North pole reversed first, producing a quadrapole. South PLUSSouth PLUSNorth PLUSNorth MINUS

How anomalous is the Sun now?

Persistent and continuous observations of sunspots for 400 years

Galileo Galilei (1612)National Astronomical Observatory of Japan (NAOJ, Tokyo, 1998)

NAOJ, solar observatory400 years of continuous observations

Few sunspot between 16451715Solar dynamo stopped?

FrozenThamesNumber of sunspots increases & decreases on 11 year cycle. Drastic decrease in sunspots observed between 1645-1715. Cold period coincides with the Maunder minimumMaunder minimumDalton minimumCalendar yearSunspot number

NAOJ, Solar ObservatoryUnusually long solar-cycle periodLaunch of Hinode

Red lineCurrent cycleBlack linespast 6 cycles overlaid, starting at the minimum.

Unusually long solar-cycle period

Cycle length 12.6 year!

Nominal cycle length 11 yearNAOJ, Solar Observatory

13.2yr12.6yr9.7yr10.7yr9.9yr

??yrIncreasing sunspot cycle period

Similar long period found 200 years agoCalendar yearSunspot number

How do we observe sunspots on the ancient Sun?

Higher solar activity Decreases cosmic rays entering Earths atmosphere Decrease in carbon-14 Decrease recorded in tree rings

EarthHeliosphere (magnetic fields)Cosmic raysSuns magnetic field hinders cosmic rays entering the solar heliosphereNitride nucleus(b)Cosmic rays bombard Earths atmosphere to generate Carbon-14Carbon cycleCarbon dioxide14CO2

Recorded in tree ringvia photosynthesis

protonAtmospheric atoms

carbon14Neutron

Carbon-146 protons and 8 neutrons

Blue dots: Miyahara et al., 2004, 2006, 2007, 2008Red dots: Damon, 2003Black curve (decadal): Stuiver et al., 1998

(Decadal)MaunderSpoererWolfDaltonOort~9yr11~13yr10~11yr 9~11yr13~14yr~14yr~13yrD14C (permil)~11yr

Higher solaractivityLower solaractivityLower solar activity is accompanied by longer cycle time and vice versa

How do we predict future solar activity?

Dynamo process inside the Sun (current paradigm)Polar magnetic fields are the source of sunspot magnetic fields. Indicate future solar activity.

Faster equatorial rotation (differential rotation)NS

Magnetic field line*NSNS

Emerged fields seen as sunspot pair

*Magnetic fields behave like rubber tube

Amplified Magnetic fields

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Rapid weakening of solar magnetic fieldNorth PoleSouth Pole

Wilcox Solar ObservatoryRoyal Observatory of BelgiumPolar Magnetic FieldSunspot Number

Year

YearCauseEffect

Magnetic field polarities flip during the solar maxima periods

Cycle period14yrCycle period13yrCycle period13yr

Is the Sun entering a stagnant period?Asymmetric polaritySunspot only in south pole(asymmetric polarity)

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now11400 years ago4000 years agoSunspot number upto 11400 years agoThe latest grand maximum started inmid-20 century and ended with thestart of new century.

From NASA D. Hatrawayhttp://solarscience.msfc.nasa.gov/predict.shtml2016 July2030Cycle 25 2025-26? SSN=50?2040Prediction of future sunspot number Cycle 24 (SSN=113 in 2014)the lowest since Cycle14 in 1905 (SSN=105)

Does sunspot number affect the Earth?

British Met Office announcement February 2015In the last 15 years, global surface warming has slowed, despite increases in greenhouse gas emissions.(http://www.metoffice.gov.uk/research/news/2015/variations-rate-global-warming)

The cherry tree historical climate monitorTemperature determines when cherry trees flower; hotter weather leads to earlier flowering, and vice versa.Using 822 years of historical records on cherry-blossom viewing parties etc, the past 1200 years of temperatures in Kyoto in March were reconstructed.Data taken between 1911 1940 was used to calibrate, confirming prediction accuracy of 0.1C. (Prof. Y. Aono, Osaka Prefecture University, Japan)Aono (2012)

Conversion of Japanese lunar calendarto modern Gregorian calendar

Kyoto: capital of Japan from 794 to 1868In diaries, chronicles, poems on flowering, viewing parties, events such as gifts to the Emperor are depicted by Emperors, aristocrats, politicians, monks, and merchants.Obtain full-flowering dates ofcherry tree (Prunus jamasakura)

Prof. Y. Aono, Osaka Prefecture University

Low temperature periods coincide in lower solar activity periodTemperature decreases occur close to end of solar minimum. (delay in a few tens of years)Reconstructed temperature and solar activity

10th century warmer than now

Aono (2012)

March mean temperatureFull-flowering dates (DOY)ReconstructedSunspot numberafter removing heat island effect

Averaged reconstructed temperaturered: 95% confidence level

Frozen Thames (1677)http://en.wikipedia.org/wiki/File:The_Frozen_Thames_1677.jpg

Sunspot number (Usoskin et al., 2007) and cold/wet conditions in Europe (Versteegh, 2005) over 6500 years: 14 cold spells vs 15 Grand minima 12 coincide.Courtesy of Ilya G. Usoskin Cold spells vs. Grand solar minima

1degree C drop2 degree C dropTemperature decrease during Maunder minimum in Kyoto

What would happen if we enter a Maunder minimum?

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How do planetary magnetic fields protect life and civilization?

saku.tsuneta@nao.ac.jp47

Sun

48Shock waves and coronal mass ejection from the Sun propagate toward the Earth in solar wind streamEarthEarth

Negative effect of disturbance

Quebec blackout (1989)Aurora

Satellites and GPS malfunction, radiation hazard

Magnetic fields of planetsEarthSaturnJupiterVenusMarsMercury

Direct interaction betweenPlanetary atmosphere andsolar windFormation of strong protective magnetosphere

weakstrong

PhotosNASA

Magnetic fields of planetsEarthSaturnJupiterVenusMarsMercury

Direct interaction betweenPlanetary atmosphere andsolar windFormation of strong protective magnetosphere

weakstrong

PhotosNASA1/100160020,000No magnetic fieldSmall fossilmagnetic field

Planets and magnetic fieldsJupiterMarsEarthVenusMercurySaturnUranusNeptune

Stripping away ancient Martian atmosphere due to intense solar stormWeak gravity struggles to hold the Martian atmosphere.Mars lost its own magnetic fields in ancient times.Young Sun emits intense UV and X-rays.Initial rich Martian atmosphere may be lost due to intense solar storms.

Earth fortunately has a magnetic field

Mars does not have any magnetic field

Mars

Humans outside our magnetic fieldThe Apollo moon missions travelled beyond the Earths magnetosphere. Apollo astronauts showed a greater risk of cardiovascular disease (CVD). CVD mortality among Apollo astronauts was almost 5 x that of non-flight or low Earth orbit astronauts.The Earths magnetosphere protects humans!Delp, M. D. et al. Apollo Lunar Astronauts Show Higher Cardiovascular Disease Mortality: Possible Deep Space Radiation Effects on the Vascular Endothelium. Sci. Rep. 6, 29901 (2016).

Do exoplanets harbor life?

saku.tsuneta@nao.ac.jp57

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100 billion stars in one galaxy100 billion galaxies in universeIn total, 10000000000000000000000000 stars!Big Questions in space science1. How did life emerge on Earth?2. Does a second Earth exist?3. Do extra-terrestrial life-forms exist?4. What is dark matter and dark energy?5. How did this universe begin and form?

Fraction of stars with at least one planet (period < 85 days)

Small17% 21% 20% 2% 2% Total=62%

If the following materials in the atmosphere are detected, life may exist.WaterOzone(oxygen)Carbon dioxideMethaneNASA WFIRSTESA-JAXA SPICA missions are expected to detect these!

Spectra of planetary atmosphere

Wavelength(micron)

Temperature (K)Venus

Gelileo Sagan1993Can species on other planets guess we are here?WaterOzoneCarbon dioxideEarthMars

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2016/9/12

How do super flares affect life and civilization on Earth and other planets?

saku.tsuneta@nao.ac.jp64

Occurrence rate of big solar flares(GOES classification in terms of X-ray intensity)Number of Solar Flares year X M C----------------1989 59 620 19291990 16 273 22621991 54 590 26531992 10 202 19221993 0 74 11421994 0 25 3361995 0 11 1481996 1 4 811997 3 21 2861998 14 94 11881999 4 170 18542000 17 215 22232001 21 310 2101

C-class flares 1000 events per yearM-class flare 100 events per yearX-class flare 10 events per yearX10-class flare 1 event per year100-class flare every 10 yearsX100000-class flare every 10000 year

Every 10 times increase,Occurrence rate one 10th

X-class solar flareSoft X-ray intensity

Largest flare ever observed:Carrington flare (1859, Sep 1, am 11:18

Richard Carrington in 1859: first record of flare observationVery bright aurora appeared next day in Cuba, the Bahamas, Jamaica, El Salvador, and Hawaii. Total energy: 1032ergEstimated to be the largest magnetic storm (> 1000 nT) in modern historyTelegraph systems all over Europe and North America failed.Telegraph pylons threw sparks and telegraph paper spontaneously caught fireLoomis1861

The solar storm (flare) on 2012 July 23 observed by STEREO is supposed to be a super-Carrington class, though it occurred on the invisible side of the Sun from the EarthIf it hit the Earth, the estimated economic impact is estimated to be >$2 trillion

A super flare recorded in Japanese cedar trees1035erg super flare? 1000 times larger than the largest flare ever observed(Miyake et al. Nature , 2012, June, 486, 240) Nature

Superflare 10000 times larger thanthe largest solar flare Maehara et al. (2012)Super flare: Total energy~1036 erg10000 times larger than the largest solar flares

Maehara et al. (2012)SunSuper flaresIntensity (visible light)Day A star with a big star spot generates super flares

Superflare C M X X10 X1000 X100000 Shibata et al. 20131000 in 1 year100 in 1 year10 in 1 year1 in 1 year1 in 10 year1 in 100 year1 in 1000 year1 in 10000 yearComparison between solar flares and superflaresLargest solar flare

Superflares 1000 times more energetic than the largest solar flares occur once in 5000 years !

Flares and origin of lifeKepler has seen 365 superflares (1033-1036 erg) on 148 sun-like stars.1035 erg superflares (1000 x the largest solar flare) occur once in 5000 years in our Sun (Maehara et al. 2012). Superflares cause strong ozone depletion and disaster for the civilization. 1037 erg superflare may cause extinction.Light-weight M-stars are very common. Their habitable zone is located much closer to the central star. M-stars produce flares with rate 100 x more than sun-like Stars. Superflares on M-type stars fatally radiate the surface of orbiting habitable planets.

SummaryIncrease and decrease of sunspots affect Earths climate.The Suns current state indicates an upcoming Maunder minimum in 20 years, resulting in global cooling of the Earth.An ultra-rare super flare could affect our civilization and life on Earth.Planets with a magnetosphere are in a better position to harbor life.

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