NASA | Goddard Space Flight Center | 2014 Oct 16
Twist, Nanoflares, Loops, ‘Bombs’ and Jets:
New Solar Findings Revealed by IRIS Observatory
Lockheed Martin Corporation | 2014 Oct 16
These images show an active solar region on June 4, 2014. The image on the left shows the chromosphere (approximately 17,500 degrees F), whereas the image at right shows the transition region, both the site of the twisting motions observed with IRIS.
Credits: IRIS/LMSAL-NASA.
(left) Tiago Pereira,
University of Oslo.
(right) Bart De Pontieu.
Just above the sun’s surface lie twisting tornadoes that accelerate plasma to speeds of over 100,000 km/hr (62,000 mph). New findings by Lockheed Martin scientists show these motions are not only more common than previously thought but also appear to heat plasma from 10,000 degrees F to at least 100,000 degrees.
An international team led by Lockheed Martin scientists discovered this and other findings that show how the sun’s atmosphere is energized. The team is using the Interface Region Imaging Spectrograph (IRIS), which has been providing new insight into the inner workings of the sun’s atmosphere since it launched in June 2013.
The discoveries were published this week in a special section of the journal Science. ...
Five articles leverage high-resolution IRIS images and spectra to present major advances in understanding how the solar atmosphere is energized.
- Nanoflares: Scientists find compelling evidence for the presence of high-energy particles generated during coronal nanoflares. These are small-scale events long thought to drive coronal heating through the release of energy when magnetic field lines reconnect. This result provides new insight into how these electrons are accelerated to such high energies.
- Transition Region Loops: Small-scale magnetic loops were found in high-resolution images of IRIS and advanced 3-D models, resolving a long-standing debate about the nature of the emission in the transition region. These results vindicate a view that this emission does not originate in the usual transition region between the surface and hot loops, but occurs in previously undiscovered loop-like structures.
- Solar “bombs”: Researchers saw in high-resolution spectra a solar atmosphere turned upside down: hot plasma at 100,000 Kelvin (nearly 180,000 degrees Fahrenheit) is found closer to the solar surface than previously imagined. The plasma is sandwiched by cool plasma both below and above, and heated by “bombs,” where magnetic fields reconnect and lead to rapid heating. These unexpected results will likely lead to a reassessment of other phenomena in the low solar atmosphere, such as the mysterious Ellerman bombs, discovered almost a century ago.
- Jets in the Wind: Scientists uncover evidence of high-speed jets at the root of the solar wind, a high-speed, continuous stream of particles that permeates space around the Earth. The jets are fountains of plasma that appear to undergo rapid heating from 20,000 to 180,000 degrees F and may provide hot plasma to the solar wind.
- Twists: As described at the opening of this article, one paper shows the chromosphere is full of twisting motions on spatial scales of a few hundred miles. These motions are a sign of magnetic waves and support recent theories about heating of the solar chromosphere and corona.
Tiny "Nanoflares" Might Heat the Sun's Corona
Harvard Smithsonian Center for Astrophysics | 2014 Oct 16
Evidence of nonthermal particles in coronal loops heated impulsively by nanoflares - P. Testa et al
- Science 346(6207) (17 Oct 2014) DOI: 10.1126/science.1255724
arXiv.org > astro-ph > arXiv:1410.6130 > 22 Oct 2014
Max Planck Institute for Solar System Research | 2014 Oct 16
Hot explosions in the cool atmosphere of the Sun - H. Peter et al
- Science 346(6207) (17 Oct 2014) DOI: 10.1126/science.1255726
arXiv.org > astro-ph > arXiv:1410.5842 > 21 Oct 2014