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Solar "Dark Energy" Illuminated
University of Hawaii scientists Dr. Haosheng Lin, Dr. Jeff Kuhn, and Mr. Roy Coulter described, for the first time, a coronal magnetogram—a "magnetic map" of the elusive magnetic field in the outer atmosphere of the Sun. Their results were presented today at the American Astronomical Society meeting in Denver, Colorado.
For many years, it has been known that the outer parts of the Sun, which extend into space and eventually influence Earth's space and upper atmospheric environment, are controlled by magnetic fields. Although these fields have been measured on the visible surface of the Sun for several decades, until now, they have evaded scientists' attempts to observe them up through the faint outer region of the Sun's atmosphere called the corona. These invisible fields are responsible for virtually all of the Sun's explosive and dynamic phenomena. The fields play a major role in causing the variations in the amount and kinds of solar radiation that affects the Earth's magnetosphere, ionosphere, and ultimately its climate.
"Our next step is to improve the resolution and to generate magnetograms that the modelers can use to improve our sketchy understanding of how the corona works," noted Lin, the lead author of this study.
"At Haleakala we built a unique solar telescope to observe the faint solar atmosphere in the presence of the bright Sun. This unusual telescope, in combination with a highly sensitive imaging infrared spectropolarimeter, is the key to revealing these coronal fields," said Kuhn.
IfA Director Dr. Rolf Kudritzki stated, "These exciting results are made possible in part because of the excellent solar observing conditions on Haleakala. The ability to finally see the Sun's coronal magnetic fields will open new opportunities for solar and solar-terrestrial research."
This work was supported by the NASA, National Science Foundation and the Air Force Office of Scientific Research.
The Institute for Astronomy at the University of Hawaii conducts research into galaxies, cosmology, stars, planets, and the Sun. Its faculty and staff are also involved in astronomy education, deep-space missions, and in the development and management of the observatories on Haleakala and Mauna Kea. Refer to http://www.ifa.hawaii.edu/ for more information about the Institute.
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Caption: Solar corona image taken with the Extreme Ultraviolet Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO). This picture shows the corona on April 6, 2004. The limb of the Sun is on the left, and the superimposed contour plot shows the strength of the magnetic field as it was measured from Haleakala by the IfA team using infrared light. The strongest magnetic field is about ten times larger than typical terrestrial field strengths at Earth’s surface. Photo Credits: NASA (SOHO/EIT) and J. R. Kuhn and H. Lin, Institute for Astronomy, University of Hawaii.