An image of a sunspot captured by NSF’s Daniel K. Inouye Solar Telescope clearly shows the potential of the telescope and its set of state-of-the-art instruments to revolutionize solar astronomy.
This image of a sunspot was taken on January 28, 2020 by NSF’s Inouye Solar Telescope’s Wave Front Correction context viewer. The image reveals striking details of the sunspot’s structure as seen at the Sun’s surface. The sunspot is sculpted by a convergence of intense magnetic fields and hot gas boiling up from below. This image uses a warm palette of red and orange, but the context viewer took this sunspot image at the wavelength of 530 nm — in the greenish-yellow part of the visible spectrum. Image credit: NSO / AURA / NSF.
NSF’s 4-m Inouye Solar Telescope, the largest optical solar telescope in the world, is located on the island of Maui in Hawai’i.
The telescope delivers spatial resolution and sensitivity that enable astronomers to unravel many of the mysteries that the Sun presents, including the origin of solar magnetism, the mechanisms of coronal heating and drivers of the solar wind, flares and coronal mass ejections.
Its state-of-the-art adaptive-optics system provides diffraction-limited imaging and the ability to resolve features approximately 20 km (12.4 miles) on the Sun.
Achieving this unprecedented spatial resolution is critical for the ability to observe solar magnetic fields at small spatial scales.
“The new sunspot image achieves a spatial resolution about 2.5 times higher than ever previously achieved, showing magnetic structures as small as 20 km on the surface of the Sun,” said Dr. Thomas Rimmele, associate director at NSF’s National Solar Observatory (NSO).
“The image reveals striking details of the sunspot’s structure as seen at the Sun’s surface.”
“The streaky appearance of hot and cool gas spidering out from the darker center is the result of sculpting by a convergence of intense magnetic fields and hot gasses boiling up from below.”
“The concentration of magnetic fields in this dark region suppresses heat within the Sun from reaching the surface.”
“Although the dark area of the sunspot is cooler than the surrounding area of the Sun, it is still extremely hot with a temperature of more than 4,150 degrees Celsius (7,500 degrees Fahrenheit).”
“This sunspot image, measuring about 16,000 km (10,000 miles) across, is just a tiny part of the Sun. However, the sunspot is large enough that Earth could comfortably fit inside.”
Sunspots are the most visible representation of solar activity. Astronomers know that the more sunspots that are visible on the Sun, the more active the Sun is.
The Sun reached solar minimum, the time of fewest sunspots during its 11-year solar cycle, in December 2019. Solar maximum for the current solar cycle is predicted in mid-2025.
The sunspot captured by the Inouye Solar Telescope was one of the first of the new solar cycle.
“With this solar cycle just beginning, we also enter the era of the Inouye Solar Telescope,” said Dr. Matt Mountain, president of the Association of Universities for Research in Astronomy (AURA), the organization that manages NSO and the Inouye Solar Telescope.
“We can now point the world’s most advanced solar telescope at the Sun to capture and share incredibly detailed images and add to our scientific insights about the Sun’s activity.”
A paper detailing the optics, mechanical systems, instruments, operational plans and scientific objectives of the Inouye Solar Telescope is published in the journal Solar Physics.
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Thomas R. Rimmele et al. 2020. The Daniel K. Inouye Solar Telescope – Observatory Overview. Solar Physics 295, 172; doi: 10.1007/s11207-020-01736-7
