The ESA/NASA SOHO spacecraft determines the origin of the fast solar wind in the magnetized atmosphere of the Sun
This picture was constructed from measurements which were made on September 21, 1996 on SOHO (see the April 22 issue of SCIENCE magazine) with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer (SUMER) providing Doppler spectroscopy of the coronal plasma, with the Michelson Doppler Imager (MDI) delivering magnetogramms of the solar photosphere, and The Extreme ultraviolet Imaging Telescope (EIT) giving the context image of the Sun in the left corner. The SUMER spectrometer analyzes ultraviolet light which is emitted by the hot gas in the Suns atmosphere, and is ideally suited for studying atmospheric motions. Careful data analysis, involving subtle wavelength calibration and coronal magnetic-field extrapolation was required before the slow outward motions could be identified at various heights above the solar surface, and their links with the magnetic field guiding the flow could be established. The figure illustrates location and geometry of three-dimensional magnetic field structures in the solar atmosphere. The magenta colored curves illustrate open field lines, and the dark gray solid arches show closed ones. In the lower plane, the magnetic field vertical component obtained at the photosphere by MDI is shown. In the upper plane, inserted at 20,600 km, we compare the Ne VIII Doppler shift with the model field. The shaded area indicates where the outflow speed of highly charged neon ions is larger than 7 km/s. Note the funnel constriction by pushing and crowding of neighboring loops. The scale of the figure is significantly stretched in the vertical direction. The smaller figure in the lower right corner shows a single magnetic funnel, with the same scale in both vertical and horizontal directions. Image: MPI for Solar System Research
A Chinese-German team of scientists have identified the magnetic structures in the solar corona where the fast solar wind originates. Using images and Doppler maps from the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer and magnetograms delivered by the Michelson Doppler Imager (MDI) on the space-based Solar and Heliospheric Observatory (SOHO) of ESA and NASA, they observed solar wind flowing from funnel-shaped magnetic fields which are anchored in the lanes of the magnetic network near the surface of the Sun. These observations are presented in the April 22 issue of Science magazine. The research leads to a better understanding of the magnetic nature of the sources of the solar wind, a stream of tenuous and hot plasma (electrically conductive gas) that affects the Earths space environment.
The solar wind consists of protons, alpha particles (two-fold ionized helium), heavy ions and electrons flowing from the surface of the Sun with speeds ranging from 300 to 800 km/s. The heavy ions in the coronal source regions emit radiation at certain ultraviolet wavelengths. When they flow towards Earth, as they do when tracing the nascent solar wind, the wavelengths of the ultraviolet emission become shorter, a phenomenon called the Doppler effect, which is well known in its acoustic variant, for example, from the change in tone of the horn of a police car while approaching to or receding from the listener. In the solar case, plasma motion towards us, which means away from the solar surface, is detected as blue shift in the ultraviolet spectrum, and thus can be used to identify the beginning of the solar wind outflow.
Dr. Andreas Trepte | EurekAlert!
From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison
Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science
On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded after a glide flight with an Airbus A320 in ditching on the Hudson River. All 155 people on board were saved.
On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded...
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
27.02.2017 | Materials Sciences
27.02.2017 | Interdisciplinary Research
27.02.2017 | Life Sciences