Sun-Earth Connectionspart of a symposium at the Tacoma campus of

The Evergreen State College14.Sept.2001

The Sun and the Earth are both getting hotter. What does the Sun’s magnetic activity have to do with it? What are the consequences?

We are investigating questions like these in classes and research at Evergreen.

Dr. E.J. Zita, The Evergreen State College, Olympia, WA

http://192.211.16.13/individuals/zita/home.htm

Outline:• Sun radiates Earth• Earth and Sun are warming• Magnetic activity heats the Sun’s atmosphere• Solar magnetism affects the Earth• How do we measure effects on Earth? On Sun?• How do magnetic fields affect the Sun?• How can we predict magnetic storms?• What can we do about it?• Evergreen contributes to understanding the Sun

Sun radiates Earth

Nuclear fusion energetic photons light and heat

Hot gas energetic charged particles solar wind

Diagrams courtesy of NCAR

Sun and Earth are warming

From Friis-Christensen, E., and K. Lassen, "Length of the solar cycle: An indicator of solar activity closely associated with climate," Science, 254, 698-700, 1991. See http://web.dmi.dk/solar-terrestrial/space_weather/

The Sun gets bigger and hotter as it grows older (billions of years).

The Earth is currently warming out of latest ice age (13,000 yrs).

Many factors contribute to (long-term) climate changes and (short-term) temperature variations on Earth.

Earth’s average temperature (blue) tracks solar activity (red).

Magnetic activity heats the Sun’s atmosphere

Diagrams courtesy of

Campfire: hot inside, cooler as you move away

Sun: Hot inside, cool surface, but hotter as you move away!

Solar magnetism affects the Earth

Movies courtesy of

Magnetic field lines snap release hot ions

• aurorae: solar ions trapped in Earth’s magnetic field

• magnetic storms power and satellite outages

How do we measure effects on Earth?

Diagram courtesy of NCAR

Solar observatories: Measure luminosity, count sunspots

Weather stations: Earth temperatures, atmospheric effects

http://mlso.hao.ucar.edu/

How do we measure effects on the Sun?

TRACE: measures fine-scale solar magnetic fields http://vestige.lmsal.com/TRACE/Project/Mission/mission.htm

SOHO: Solar and Heliospheric Observatory: coronal spectra http://nssdc.gsfc.nasa.gov/nmc/tmp/1995-065A.html

YOHKOH: (Japanese for sunbeam) measures high-energy radiation from solar flares (X-rays and neutrons) and quiet structures and pre-flare conditions. http://nssdc.gsfc.nasa.gov/nmc/tmp/1991-062A.html http://www.solar.isas.ac.jp/english/yohkoh_background2.html

How do magnetic fields affect the Sun?

Diagram courtesy of Gregory, Stephen A., and Michael Zeilik. Introductory Astronomy and Astrophysics.

Magnetic field lines rise from inside sun sunspots

Twisted field lines increased magnetic energy

Magnetic reconnection release particles and kinetic energy

Magnetic waves heating

Figure 4

Figure 3

Gregory, p.220

Magnetic waves in Sun’s atmosphere

Created with 3D MHD code by Rosenthal et al., Oslo

Research by Evergreen students at NCAR, Boulder

Sara Petty-Powell and Matt Johnson

How can we predict magnetic storms?

Diagrams courtesy of Montana State University and NCAR

Twisting magnetic fields s-shaped filaments on photosphere

field lines snap and reconnect energy release

Dooling, p. 2(Dooling, Dave. p. 2)

Figure 9

Waves in twisted magnetic fields

Diagrams courtesy of Montana State University

Research by Evergreen faculty at NCAR, BoulderE.J. Zita with Tom Bogdan and B.C. Low

What can we do about it?

• Not a darn thing? the Sun does what it will

• prevention: redesign power circuits and satellites

• understand the Sun better: predict magnetic storms and protect satellites

• enjoy the increased warmth and aurorae

Evergreen contributes understanding

Theory: Zita calculates magnetic waves in Sun’s atmosphere

Modeling: colleagues in Oslo solve equations with computers to generate numerical data (Rosenthal et al.)

Observations: colleagues at NCAR and elsewhere observe Sun with satellites to get real data (Lites et al.)

Analysis: Students help us understand how numerical data connects to theory and real data (Bogdan et al.)

theory

modeling

Observations

analysis

Summary

Diagram courtesy of HAO and WET

Solar magnetic activity greater energy from Sun

greater temperatures, aurorae, magnetic storms on Earth

Multifacted collaboration

better understanding of Sun and Earth

Selected references GONG & NOAO = Global Oscillation Network Group http://www.gong.noao.edu/gonghome.html, http://helios.tuc.noao.edu/

NCAR = National Center for Atmospheric Research, Boulder, CO http://www.hao.ucar.edu/public/education/slides/slides.html

MSU = Montana State University http://solar.physics.montana.edu

Stanford Solar Center http://solar-center.stanford.edu

SOHO: http://sohowww.nascom.nasa.gov/Kaler, James B. Stars . New York: Scientific American Library, 1992. http://fusedweb.pppl.gov/CPEP/Chart_Pages/5.Plasmas/SunLayers.html#BibNASA: http://hesperia.gsfc.nasa.gov/sftheory/index.htmInstitute for Physics and Astronomy, Aarhus University, Denmark http://www.obs.aau.dk/helio_outreach/

Waves in the magnetic solar atmosphere I, Colin Rosenthal and Tom Bogdan, Astrophysical Journal, 2001

Energy transport by waves above the photosphere, Sara Petty-Powell and Matt Johnson, 2001

Wave transformations in a sheared, force-free magnetic field, E.J. Zita, 2001http://192.211.16.13/individuals/zita/research.htm