Bernd Heber on behalf of the KET team
Rome, 12.05.2009
Mathematisch-Naturwissenschaftliche Fakultät
Ulysses: Cosmic rays in 4 Dimensions
Outline
Mathematisch-Naturwissenschaftliche Fakultät
• The Sun and the Heliosphere • The Ulysses mission• Energetic Particles (in the heliosphere)• Importance of the polar regions (Ulysses results)• Summary and Outlook
The Sun and the Heliosphere
Mathematisch-Naturwissenschaftliche Fakultät
Mathematisch-Naturwissenschaftliche Fakultät
• The Atmosphere of the Sun extends into interstellar space
• Forming the heliosphere
• Termination shock (90 AU)
• Heliopause (180 AU)• Bow shock (350 AU)
What is Ulysses?
Mathematisch-Naturwissenschaftliche Fakultät
Ulysses is ...• A collaborative project between ESA and NASA
• The only space-probe in a solar-polar orbit
• A mission to explore the heliosphere as an integrated system and conduct investigations of the Sun, the local interstellar medium, and the universe
History ...• A mission that eventually became Ulysses was
proposed as early as 1959 (2 years after Sputnik!)
• The project started officially in 1977, with a launch foreseen in 1983
• After many delays, Ulysses was finally launched on 6 October 1990, from the space shuttle Discovery
Exploration of the polar regions by Ulysses
Mathematisch-Naturwissenschaftliche Fakultät
Mathematisch-Naturwissenschaftliche Fakultät
McComas et al., GRL, 2002
Photons: direct connection
g
Propagation
e+e-
Charged particles: Reflection in galactic magnetic fields
Modulation in the heliosphere
Space probes in the heliosphere
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• 1 AU: IMP, ACE, Sampex, SOHO, STEREO, neutron monitors, and PAMELA
• Ulysses: (1.3<r< 5AU 80,2 < θ < 80,2)
• Voyager 1 (r >100 AU)
• Voyager 2 (r>80 AU
Observations of galactic cosmic rays in the heliosphere:Solar modulation at neutron monitor energies
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• Variations with the 11-year solar magnetic cycle
• The amplitude depend on particle rigidity
Observations of galactic cosmic rays in the heliosphere:Charge sign dependence
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• Shape and amplitude depend on particle charge sign
• Solar modulation cycle is the 22-year Hale cycle
Observations of galactic cosmic rays in the heliosphere
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Latitudinal Gradient
Radial Gradient
Exploration of the polar regions by Ulysses
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Kiel Electron Telescope on board Ulysses
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Relativistic Electrons: ~10 Minutes
50 MeV Protons: 30-80 Minutes
Kiel Electron Telescope on board Ulysses
Mathematisch-Naturwissenschaftliche Fakultät
Relativistic Electrons: ~10 Minutes
50 MeV Protons: 30-80 Minutes
Ulysses COSPIN/KET observations
Three fast latitde scans:
1.1994/1995: Solar minimum; A>0-magnetic epoch2.2000/2001: Solar maximum3.2007/2008: : Solar minimum; A<0-magnetic epoch
The heliosphere and the heliospheric magnetic field
Mathematisch-Naturwissenschaftliche Fakultät
• Expectation in the 1970’s for galactic cosmic ray intensities over the poles of the Sun
Cosmic ray distribution at solar minimum (A > 0)
Mathematisch-Naturwissenschaftliche Fakultät
The LIS ca
n not be m
easured over t
he poles
of the Sun
Expectation before Ulysses:Ulysses will measure the LIS over the poles of the Sun
Electron gradients at solar minimum (A > 0)
Mathematisch-Naturwissenschaftliche Fakultät
Electrons s
how no latitudinal g
radient
The heliosphere and the heliospheric magnetic field
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• Drift pattern in the Parker like heliospheric magnetic field
Ulysses COSPIN/KET observations
Three fast latitde scans:
1.1994/1995: Solar minimum; A>0-magnetic epoch2.2000/2001: Solar maximum3.2007/2008: : Solar minimum; A<0-magnetic epoch
Electron gradients during the A<0-magnetic epoch
Mathematisch-Naturwissenschaftliche Fakultät
The fourth dimension: The solar cycle
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Variations with the 22-year solar magnetic cycle
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Mathematisch-Naturwissenschaftliche Fakultät
Tilt [degree]
Consequences for the recent solar minimum
Mathematisch-Naturwissenschaftliche Fakultät
The galactic c
osmic r
ay intensit
y should
increase by m
ore than 20% w
hen the tilt a
ngle
drops below 10o
Summary
Mathematisch-Naturwissenschaftliche Fakultät
• The galactic cosmic ray intensity is altered by solar modulation
• Latitudinal gradients of protons and electrons in the inner heliosphere are smaller than expected and even vanishing for the A>0-solar magnetic epoch.
• The opposite is true for the A<0-solar magnetic epoch.• Current solar minimum remarkable because tilt and
sunspot number out of phase• Simultaneous electron and proton measurements
allow to predict the real solar minimum flux.
Mathematisch-Naturwissenschaftliche Fakultät
The galactic c
osmic r
ay dist
ribution sh
ows a
North-South Asym
metry1. No gradient →
ratio = 12. Latitudinal
gradient → ratio depend on latitude (He)
3. GCR-distribution expected to be symmetric around the heliospheric equator