Resembling the puffs of smoke and sparks from a summer fireworks
display in this image from NASA's Hubble Space Telescope, these
delicate filaments are actually sheets of debris from a stellar
explosion in a neighboring galaxy. Hubble's target was a supernova
remnant within the Large Magellanic Cloud (LMC), a nearby, small
companion galaxy to the Milky Way visible from the southern
Denoted N 49, or DEM L 190, this remnant is from a massive star
that died in a supernova blast whose light would have reached
Earth thousands of years ago. This filamentary material will
eventually be recycled into building new generations of stars in
the LMC. Our own Sun and planets are constructed from similar
debris of supernovae that exploded in the Milky Way billions of
years ago. This seemingly delicate structure also harbors a very powerful spinning neutron star that may be the central remnant from the initial blast. It is quite common for the core of an exploded supernova star to become a spinning neutron star (also called a pulsar - because of the regular pulses of energy from the rotational spin) after the immediate shedding of the star's outer layers. In the case of N 49, not only is the neutron star spinning at a rate of once every 8 seconds, it also has a super-strong magnetic field a thousand trillion times stronger than Earth's magnetic field. This places this star into the exclusive class of objects called "magnetars." On March 5, 1979, this neutron star displayed an historic gamma-ray
burst episode that was detected by numerous Earth-orbiting
satellites. Gamma rays have a million or more times the energy of
visible light photons. The Earth's atmosphere protects us by
blocking gamma rays that originate from outer space. The neutron
star in N 49 has had several subsequent gamma-ray emissions, and is
now recognized as a "soft gamma-ray repeater." These objects are a
peculiar class of stars producing gamma rays that are less energetic
than those emitted by most gamma-ray bursters. The neutron star in N 49 is also emitting X rays, whose energies are slightly less than that of soft gamma rays. High-resolution X-ray satellites have resolved a point source near the center of N 49, the likely X-ray counterpart of the soft gamma-ray repeater. Diffuse filaments and knots throughout the supernova remnant are also visible in X ray. The filamentary features visible in the optical image represent the blast wave sweeping through the ambient interstellar medium and nearby dense molecular clouds. Today, N 49 is the target of investigations led by Hubble astronomers
You-Hua Chu from the University of Illinois at Urbana-Champaign and
Rosa Williams from the University of Massachusetts. Members of this science team are interested in understanding whether small cloudlets in the interstellar medium of the LMC may have a marked effect on the physical structure and evolution of this supernova remnant.
The Hubble Heritage image of N 49 is a color representation of data
taken in July 2000, with Hubble's Wide Field Planetary Camera 2. Color filters were used to sample light emitted by sulfur ([S II]), oxygen ([O III]), and hydrogen (H-alpha). The color image has been superimposed
on a black-and-white image of stars in the same field also taken with Hubble.
Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Acknowledgment: Y.-H. Chu (UIUC), S. Kulkarni (Caltech) and R. Rothschild (UCSD)