Complex Solar Surface Imaged
KATLENBURG-LINDAU, Germany, Nov. 17, 2009 – The Sunrise balloon-borne telescope, a collaborative project between Max Planck Institute for Solar System Research (MPS) and partners in Spain and the US, has delivered images that show the complex interplay on the solar surface to a level of detail never before achieved.
Packages of gas that rise and sink on the sun lend to its grainy-looking surface structure. Behind the dark spots that appear and disappear are the magnetic fields – the engines of it all.
Grainy sun: The images show the so-called granulation in four wavelengths in near-ultraviolet light. The image section depicts 1/20,000 of the entire surface. The smallest recognizable structures have an angular resolution equal to that when looking at a coin from a distance of 100 km (more than 62 miles). The light structures are the foundational elements of the magnetic fields. (Image: MPI for Solar System Research)
On June 8, 2009, the Sunrise, the largest solar telescope ever to have left Earth, was launched from the Esrange Space Center in Kiruna, northern Sweden. In its entirety, the equipment weighed in at more than six tons on launch. Carried by a gigantic helium balloon with a capacity of 1 million cm and a diameter of around 130 m (426.5 ft), Sunrise reached a cruising altitude of 37 km (23 miles) above the Earth’s surface.
The observation conditions in this layer of the atmosphere, known as the stratosphere, are similar to those in outer space. Here, the images are no longer affected by air turbulence, and the camera can also zoom in on the sun in ultraviolet light, which otherwise would be absorbed by the ozone layer.
After separating from the balloon, Sunrise parachuted safely to Earth on June 14, landing on Somerset Island, in Canada’s Nunavut Territory. This remote region is situated in the Northwest Passage, the seaway through the Arctic Ocean between the Atlantic and the Pacific.
The IMaX instrument not only depicts the solar surface but also makes magnetic fields visible; these appear as black or white structures in the polarized light. The Sunrise telescope enables tiny magnetic fields on the surface of the sun to be measured at a level of detail never before achieved. (Image: MPS/IMaX consortium)
Although the work of analyzing the total of 1.8 Tb of observation data recorded by the telescope during its five-day flight has only just begun, the first findings already give a promising indication that the mission will bring our understanding of the sun and its activity a great leap forward. What is particularly interesting is the connection between the strength of the magnetic field and the brightness of tiny magnetic structures. Because the magnetic field varies in an 11-year cycle of activity, the increased presence of these foundational elements brings a rise in overall solar brightness – resulting in greater heat input to the Earth.
The variations in solar radiation are particularly pronounced in ultraviolet light. This light does not reach the surface of the Earth – the ozone layer absorbs and is warmed by it. During its flight through the stratosphere, Sunrise carried out the first-ever study of the bright magnetic structures on the solar surface in this important spectral range with a wavelength of between 200 and 400 nm (millionths of a millimeter).
“Thanks to its excellent optical quality, the SUFI instrument was able to depict the very small magnetic structures with high-intensity contrast, while the IMaX instrument simultaneously recorded the magnetic field and the flow velocity of the hot gas in these structures and their environment,” said Dr. Achim Gandorfer, project scientist for Sunrise at the Max Planck Institute.
Previously, the observed physical processes could be simulated only with complex computer models.
“Thanks to Sunrise, these models can now be placed on a solid experimental basis,” explained professor Manfred Schüssler, solar scientist at the MPS and co-founder of the mission.
Besides the Max Planck Institute for Solar System Research, numerous other research facilities are involved in the Sunrise mission: the Kiepenheuer Institute for Solar Physics in Freiburg, the High Altitude Observatory in Boulder, Col., the Instituto de Astrofisica de Canarias on Tenerife, the Lockheed-Martin Solar and Astrophysics Laboratory in Palo Alto, Calif., NASA’s Columbia Scientific Ballooning Facility and the Esrange Space Center.
The project is funded by the Federal Ministry of Economics through the German Aerospace Centre (DLR).
For more information, visit: www.mps.mpg.de
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