February 3, 2016 – Researchers around the world are studying the sun to better understand its formation, evolution, and impact on Earth. By combining data from space-based observatories, such as NASA’s Interface Region Imaging Spectrograph (IRIS), with high-performance computer modeling, simulation, and analysis back on Earth, scientists hope to increase their understanding of solar dynamics.
Scientists are using images from IRIS to improve current solar simulations by studying discrepancies between the IRIS observations and simulated images created through numerical modeling on one of the world’s fastest supercomputers, Pleiades, which is located at the NASA Advanced Supercomputing (NAS) facility at Ames Research Center. With higher resolution and increasing complexity, future simulations will more closely match the spacecraft’s data, providing a better understanding of the Sun.
Researchers are using these numerical models to learn how magnetic fields generated in the sun’s interior affect its lower atmosphere, or chromosphere, which is the source of the ultraviolet radiation that reaches Earth. These findings may also solve several longstanding mysteries, such as why the outer atmosphere of the Sun — the corona — is millions of degrees hotter than its surface.
IRIS was built by Lockheed Martin Solar and Astrophysics Laboratory, which leads the science investigation and has operated the spacecraft since its launch in 2013.
IRIS is a NASA Explorer Mission to observe how solar material moves, gathers energy and heats up as it travels through a little-understood region in the sun’s lower atmosphere. This interface region between the sun’s photosphere and corona powers its dynamic million-degree atmosphere and drives the solar wind. The interface region also is where most of the sun’s ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth’s climate.
IRIS carries a single instrument: an ultraviolet telescope combined with an imaging spectrograph. The telescope’s primary mirror has a diameter of about eight inches (20 cm). While it can only see about one percent of the sun at a time, it’s able to resolve that image to show features that are as small as 150 miles (240 km) on the sun. Such high resolution serves as a microscope for larger instruments that capture images of the whole sun simultaneously.
The images from IRIS’s telescope record observations of material at specific temperatures, ranging from 5000 K and 65,000 K (and up to 10 million K during solar flares). This range is tailored to observe material traveling on the surface of the sun, called the photosphere, and in the lowermost layers of the atmosphere, called the chromosphere and transition region.
The spectrograph observes material at temperatures from 5,000 K to 10 million K. Spectra provide information on exactly how much light is visible from any specific wavelength. This, in turn, corresponds to how much material is present at specific velocities, temperatures and densities.
The instrument captures a new image every five to ten seconds, and spectra about every one to two seconds.