NuSTAR Discoveries

Cassiopeia A Supernova Remnant

This new view of the historical supernova remnant Cassiopeia A, located 11,000 light-years away, was taken by NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR.  Blue colour indicates the highest energy X-ray light, where NuSTAR has made the first resolved image ever of this source.  Red and green show the lower end of NuSTAR's energy range, which overlaps with NASA's high-resolution Chandra X-ray Observatory.  Light from the stellar explosion that created Cassiopeia A is thought to have reached Earth about 300 years ago, after travelling 11,000 years to get here. While the star is long dead, its remains are still bursting with action.  The outer blue ring is where the shock wave from the supernova blast is slamming into surrounding material, whipping particles up to within a fraction of a percent of the speed of light.  NuSTAR observations should help solve the riddle of how these particles are accelerated to such high energies.

Technical details: X-ray light with energies between 10 and 20 kilo-electron volts are blue; X-rays of 8 to 10 kilo-electron volts are green; and X-rays of 4.5 to 5.5 kilo-electron volts are red.  The starry background picture is from the Digitized Sky Survey.

 Spiral Galaxy IC 342

In this new view of spiral galaxy IC 342, also known as Caldwell 5, NuSTAR data has been superimposed on a visible-light view highlighting the galaxy and its star-studded arms. High-energy X-ray data from NuSTAR have been translated to the colour magenta.  NuSTAR is the first orbiting telescope to take focused pictures of the cosmos in high-energy X-ray light; previous observations of this same galaxy taken at similar wavelengths blurred the entire object into one pixel.  The two magenta spots are blazing black holes first detected at lower-energy X-ray wavelengths by NASA's Chandra X-ray Observatory.  With NuSTAR's complementary data, astronomers can start to home in on the black holes' mysterious properties.  The black holes appear much brighter than typical stellar-mass black holes, such as those that pepper our own galaxy, yet they cannot be supermassive black holes or they would have sunk to the galaxy's centre.  Instead, they may be intermediate in mass, or there may be something else going on to explain their extremely energetic state.  IC 342 lies 7 million light-years away in the Camelopardalis constellation.  The outer edges of the galaxy cannot be seen in this view.

The NuSTAR X-ray data was taken at 10 to 35 kilo-electron volts.  The visible-light image is from the Digitized Sky Survey.

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