Wavelengths of light from three space observatories are overlapped to provide a unique view of the Sun in the image at left. The high-energy X-ray light detected by one of those observatories, NASA’s NuSTAR, is seen isolated at right; a grid was added to indicate the Sun’s surface.Credits: NASA/JPL-Caltech/JAXA
Some of the hottest spots in the Sun’s atmosphere appear in the telescope’s X-ray view.
Even on a sunny day, human eyes can’t see all the light our nearest
star gives off. A new image displays some of this hidden light,
including the high-energy X-rays emitted by the hottest material in the
Sun’s atmosphere, as observed by NASA’s Nuclear Spectroscopic Telescope
Array (NuSTAR).
While the observatory typically studies objects outside our solar
system – like massive black holes and collapsed stars – it has also
provided astronomers with insights about our Sun.
In the composite image above (left), NuSTAR data is represented as blue and is overlaid with observations by the X-ray Telescope (XRT) on the Japanese Aerospace Exploration Agency’s Hinode mission, represented as green, and the Atmospheric Imaging Assembly (AIA) on NASA’s Solar Dynamics Observatory (SDO), represented as red. NuSTAR’s relatively small field of view means it can’t see the entire Sun from its position in Earth orbit, so the observatory’s view of the Sun is actually a mosaic of 25 images, taken in June 2022.
The high-energy X-rays observed by NuSTAR appear at only a few locations in the Sun’s atmosphere. By contrast, Hinode’s XRT detects low-energy X-rays, and SDO’s AIA detects ultraviolet light – wavelengths that are emitted across the entire face of the Sun.
The Sun appears different depending on who’s looking. From left, NASA’s NuSTAR sees high-energy X-rays; the Japanese Aerospace Exploration Agency’s Hinode mission sees lower energy X-rays; and NASA’s Solar Dynamics Observatory sees ultraviolet light. Credits: NASA/JPL-Caltech/JAXA
NuSTAR’s view could help scientists solve one of the biggest mysteries about our nearest star: why the Sun’s outer atmosphere, called the corona, reaches more than a million degrees – at least 100 times hotter than its surface. This has puzzled scientists because the Sun’s heat originates in its core and travels outward. It’s as if the air around a fire were 100 times hotter than the flames.
The source of the corona’s heat could be small eruptions in the Sun’s atmosphere called nanoflares. Flares are large outbursts of heat, light, and particles visible to a wide range of solar observatories. Nanoflares are much smaller events, but both types produce material even hotter than the average temperature of the corona. Regular flares don’t happen often enough to keep the corona at the high temperatures scientists observe, but nanoflares may occur much more frequently – perhaps often enough that they collectively heat the corona.
More About the MissionIn the composite image above (left), NuSTAR data is represented as blue and is overlaid with observations by the X-ray Telescope (XRT) on the Japanese Aerospace Exploration Agency’s Hinode mission, represented as green, and the Atmospheric Imaging Assembly (AIA) on NASA’s Solar Dynamics Observatory (SDO), represented as red. NuSTAR’s relatively small field of view means it can’t see the entire Sun from its position in Earth orbit, so the observatory’s view of the Sun is actually a mosaic of 25 images, taken in June 2022.
The high-energy X-rays observed by NuSTAR appear at only a few locations in the Sun’s atmosphere. By contrast, Hinode’s XRT detects low-energy X-rays, and SDO’s AIA detects ultraviolet light – wavelengths that are emitted across the entire face of the Sun.
The Sun appears different depending on who’s looking. From left, NASA’s NuSTAR sees high-energy X-rays; the Japanese Aerospace Exploration Agency’s Hinode mission sees lower energy X-rays; and NASA’s Solar Dynamics Observatory sees ultraviolet light. Credits: NASA/JPL-Caltech/JAXA
NuSTAR’s view could help scientists solve one of the biggest mysteries about our nearest star: why the Sun’s outer atmosphere, called the corona, reaches more than a million degrees – at least 100 times hotter than its surface. This has puzzled scientists because the Sun’s heat originates in its core and travels outward. It’s as if the air around a fire were 100 times hotter than the flames.
The source of the corona’s heat could be small eruptions in the Sun’s atmosphere called nanoflares. Flares are large outbursts of heat, light, and particles visible to a wide range of solar observatories. Nanoflares are much smaller events, but both types produce material even hotter than the average temperature of the corona. Regular flares don’t happen often enough to keep the corona at the high temperatures scientists observe, but nanoflares may occur much more frequently – perhaps often enough that they collectively heat the corona.
Although individual nanoflares are too faint to observe amid the
Sun’s blazing light, NuSTAR can detect light from the high-temperature
material thought to be produced when a large number of nanoflares occur
close to one another. This ability enables physicists to investigate how
frequently nanoflares occur and how they release energy.
The observations used in these images coincided with the 12th close approach to the Sun, or perihelion, by NASA’s Parker Solar Probe, which is flying closer to the our star than any other spacecraft in
history. Taking observations with NuSTAR during one of Parker’s
perihelion passes enables scientists to link activity observed remotely
in the Sun’s atmosphere with the direct samples of the solar environment
taken by the probe.
NuSTAR launched on June 13, 2012. A Small Explorer mission led by
Caltech in Pasadena, California, and managed by JPL for NASA’s Science
Mission Directorate in Washington, it was developed in partnership with
the Danish Technical University (DTU) and the Italian Space Agency
(ASI). The telescope optics were built by Columbia University, NASA’s
Goddard Space Flight Center in Greenbelt, Maryland, and DTU. The
spacecraft was built by Orbital Sciences Corp. in Dulles, Virginia.
NuSTAR’s mission operations center is at the University of California,
Berkeley, and the official data archive is at NASA’s High Energy
Astrophysics Science Archive Research Center. ASI provides the mission’s
ground station and a mirror data archive. Caltech manages JPL for NASA.
For more information on NuSTAR, visit: www.nustar.caltech.edu
Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
626-808-2469
calla.e.cofield@jpl.nasa.gov
Editor: Naomi Hartono
