                        Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                               2024 August 23

                           Supernova Remnant CTA 1
                    Image Credit & Copyright: Thomas Lelu

   Explanation: There is a quiet pulsar at the heart of CTA 1. The
   supernova remnant was discovered as a source of emission at radio
   wavelengths by astronomers in 1960 and since identified as the result
   of the death explosion of a massive star. But no radio pulses were
   detected from the expected pulsar, the rotating neutron star remnant of
   the massive star's collapsed core. Seen about 10,000 years after the
   initial supernova explosion, the interstellar debris cloud is faint at
   optical wavelengths. CTA 1's visible wavelength emission from still
   expanding shock fronts is revealed in this deep telescopic image, a
   frame that spans about 2 degrees across a starfield in the northern
   constellation of Cepheus. While no pulsar has since been found at radio
   wavelengths, in 2008 the Fermi Gamma-ray Space Telescope detected
   pulsed emission from CTA 1, identifying the supernova remnant's
   rotating neutron star. The source has been recognized as the first in a
   growing class of pulsars that are quiet at radio wavelengths but pulse
   in high-energy gamma-rays.

                      Tomorrow's picture: light-weekend
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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