The recent solar minimumHow unprecedent is the Sun's behavior?

Andrea OpitzCESR (CNRS-UPS)

University of Toulouse, France

University of Bern, 17th November 2010

Solar - terrestrial relations

Solar activity cycles

SOHO (NASA/ESA)

Solar activity cycles

David Hathaway, NASA Marshall Space Flight Center

Few hundred years of sunspot record available

Space Age (1960's - today): just a few solar cycles, low statistics

SOHO/EIT (ESA/NASA)

Out-of-ecliptic view

SW velocity vs. latitude

McComas et al. GRL 2008

Solar minimum Solar maximum Now

In-ecliptic view

Twin STEREO spacecraft

Opitz, Karrer, Wurz et al. 2009 Solar Physics

STEREO PLASTIC

SW bulk velocity

SW temperature

SW density

Group:P. Bochsler, P. Wurz, R. Karrer, A. Opitz, L. Blush, H. Daoudi, J. Fischer, M. Sigrist et al. (UoBe)A. B. Galvin, L. Kistler et al. (UNH)

Temporal evolution of the solar wind

PLASTIC proton velocity

0.5 day: ~0.95

2 days: ~0.85

SWEA electron density 0.5 day: ~0.80

2 days: ~0.65

Opitz et al. 2009, Solar Physics

Opitz et al. 2010, Solar Physics

STA STB

STA STB

SWEA

Riley, Luhmann, Opitz, Linker, and Mikic 2010 JGR

Temporal evolution by cross-correlation

STA STB

timelag of ~6 days

Recent Sun and solar wind observations: Facts

• longer solar activity minimum

• solar magnetic field weaker

• coronal holes at low latitudes

• recurrent stream structure broader

• low solar wind densities

• total solar irradiance lower

Solar activity minimum: longer

Russell, Luhmann, Jian et al. 2010

Solar polar magnetic field: weaker

red: South

blue: North

Wilcox Solar Observatory

SW velocity vs. latitude

Solar minimum Solar maximum Now

McComas et al. GRL 2008

Recurrent stream structure:stronger and broader

Gibson et al. 2009

Terrestrial response 1

• Quiet solar minimum, though geoeffective.

• Interaction of the strong, broad stream structures with the terrestrial magnetosphere.

• Proof: sunspot number alone can not give a good prediction.

Solar irradiance

TSI lower

UV lower

visible higher

Haigh 2007

Solomon et al. 2010

Solar irradiance: EUV

Terrestrial response 2

• Opportunity to separate the climatic effects of solar and anthropogenic sources.– Total solar irradiance lower.– Spectral solar irradiance: UV lower, visible

higher.

• Maunder and Dalton minimums

Russell, Luhmann, Jian 2010

Solar maximum predictions

• weaker

• normal

• stronger

Solar eruption risks

• telegraph system collapsed in 1859• electric network collapsed in 1989

• electric, oil and gas network• satellites: GPS, communication and scientific• pilots and astronauts• radio communication

Summary

• longer solar activity minimum

• solar magnetic field weaker

• coronal holes at low latitudes

• recurrent stream structure broader

• low solar wind densities

• total solar irradiance lower

Questions to the audience

• How much does such an unprecedent solar behavior influence your work?– Climatology?– Planetology?– Cosmic rays?– Space instrumentation?– Solar and Stellar Physics?

Dr. Andrea OPITZ, CESR (CNRS-UPS), University of Toulouse, France

Acknowledgements

• Cecile Bonneau: 'Science et vie' -> Nov/Dec 2010• Janet Luhmann: solar wind structures• STEREO PLASTIC: P. Bochsler, P. Wurz, R.

Karrer, A. Opitz, L. Blush et al. (UoBe) + UNH