Twisted Solution to Sun's Mystery Heat

Taken with Hinode’s X-ray telescope, this image shows details of magnetic field structures along an active region of the Sun. CREDIT: JAXA/NASA/SAO

Like cosmic rubber bands, twisted magnetic structures along the Sun's surface can release massive amounts of energy when relaxed. The discharge could be the "hidden" source that heats up the atmosphere of the Sun.

The findings, presented today at a NASA Space Science Update in Washington D.C., come from images taken by the X-ray telescope (XRT) aboard the Japan Aerospace Exploration Agency's satellite, Hinode. Formerly known as Solar-B, Hinode (Japanese for "sunrise") was launched on Sept. 22, 2006 on a three-year mission to study the Sun.

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While the Sun's surface is a steamy 10,000 degrees Fahrenheit (5,538 degrees Celsius), gas floating above in the so-called corona soars to more than 100 times hotter. Astronomers have long puzzled over the source of the corona's heat.

Hinode's telescope imaged the million-degree gas spiraling up from sunspots as well as the corona gas in the Sun's atmosphere. The pictures revealed twisted and tangled magnetic fields that could give this hot outer layer a jolt of heat. The arcing magnetic structures store huge amounts of energy, which they can release when they unwind into simpler configurations. The astronomers suggest the released energy heats up the corona and powers solar eruptions and coronal mass ejections.

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"Theorists suggested that twisted, tangled magnetic fields might exist," said study presenter Leon Golub, senior astrophysicist at the Harvard-Smithsonian Center for Astrophysics. "With the XRT, we can see them clearly for the first time."

Along with the X-ray telescope aboard Hinode, the Solar Optical Telescope (SOT) will provide images of features on the Sun's surface, while the Extreme Ultraviolet Imaging Spectrometer (EIS) can track charged solar material as it moves around. Together the trio is expected to help astronomers understand and forecast solar flares and other types of space weather.

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