The first images from NASA's Transition Region and Coronal Explorer (TRACE) spacecraft reveal activity in the solar atmosphere in stunning detail and include the first detailed observations of a magnetic energy release, called a magnetic reconnection.
The magnetic reconnection was observed on May 8, 1998, in a region of the solar atmosphere where two sets of perpendicular magnetic loops expanded into each other. Magnetic reconnection occurs when magnetic fields "snap" to a new, lower energy configuration, much like when a twisted rubber band unwinds or breaks. A magnetic reconnection can release vast amounts of energy and is responsible for explosive events on the Sun, such as flares, that can cause communication and power system disruptions on Earth.
High resolution movies of a relatively small but clear magnetic reconnection event and other spectacular solar activity observed by TRACE were presented today during the spring meeting of the American Geophysical Union in Boston.
"The TRACE spacecraft is unique in that it has both high spatial and temporal resolution in the extreme ultraviolet, wavelengths of light that reveal the multimillion degree temperature of the Sun," said Dr. Alan Title, TRACE Principal Investigator from the Stanford Lockheed Institute for Scientific Research (SLISR) in Palo Alto, CA. "We can image solar activity in finer detail than existing spacecraft, and we can take a new image once every few seconds. Both are necessary for our mission, which is to understand in great detail how energy is transported from the solar surface into the outer atmosphere. In the past, spacecraft of lower resolution were forced to average over much larger areas and periods of time. This made it difficult to get at the fundamental physics."
"In our magnetic reconnection movie, we can distinguish the fine details of the magnetic fields and see how they change during time periods of about a minute. TRACE has given us many surprises, and new ones occur nearly every observation. We found that even large areas of the Sun, some more than 60,000 miles long, can heat up or cool down significantly and thus appear and disappear in just a few minutes," said Title.
The TRACE spacecraft, launched from Vandenberg AFB, CA, on April 1, 1998, joins a multinational fleet of International Solar Terrestrial Physics project spacecraft studying the Sun during a critical period when solar activity is beginning its rise to a peak early in the new millennium. The Sun goes through an 11-year cycle from a period of numerous intense storms and sunspots to a period of relative calm and then back again. The coming months in the Sun's cycle will provide solar scientists with periods of intense solar activity interspersed with periods when the Sun is relatively passive and quiet. This will give TRACE the chance to study the full range of solar conditions, even in its relatively short planned lifetime.
TRACE is training its powerful telescope on the so-called "transition region" of the Sun's atmosphere, a dynamic region between the relatively cool surface and lower atmosphere regions of the Sun (about 10,000 degrees Fahrenheit) and the extremely hot upper atmosphere called the corona (up to three million degrees Fahrenheit). Using portions of the telescope sensitive to extreme-ultraviolet and ultraviolet wavelengths of light, TRACE is studying the detailed connections between the fine-scale surface features and the overlying, changing atmospheric structures of hot, electrically charged gas called plasma. The surface features and atmospheric structures are linked by fine-scale solar magnetic fields. The solar atmosphere is constantly evolving because the magnetic fields that dominate the corona are continuously displaced by the convective motions in the outer layers of the Sun just below the photosphere.
The TRACE science team also will study the evolution of events, such as massive flarings and huge eruptions, in the Sun's atmosphere. These events originate at the Sun's visible surface, the photosphere, and travel upward through its atmosphere (chromosphere and transition region), and then into its super-hot corona before speeding out into space, sometimes towards Earth.
The power of the TRACE telescope to do detailed studies of the solar atmosphere makes this observatory unique among the current group of spacecraft studying the Sun. The spacecraft has roughly 10 times the temporal resolution and five times the spatial resolution of previously launched solar spacecraft. A Sun-synchronous orbit is uninterrupted by EarthÕs shadow for eight months at a time, allowing the mission the greatest chance to observe the random processes which lead to flares and massive eruptions in the Sun's atmosphere.
The TRACE core team consists scientists from Lockheed Martin Advanced Technology Center, Stanford University, NASAÕs Goddard Space Flight Center, the University of Chicago, Montana State University, and the Harvard-Smithsonian Center for Astrophysics. Images to support this story are available at:
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