An international team of astronomers from Australia and Hong
Kong using the Australia Telescope Compact Array has observed the
supernova remnant 1987A in unprecedented detail at radio wavelengths
In February 1987 astronomers observing the Large Magellanic Cloud, a nearby dwarf galaxy,
noticed the sudden appearance of what looked like a new star. In fact
they weren’t watching the beginnings of a star but the end of one and
the brightest supernova seen from Earth in the four centuries since the
telescope was invented.
In the 25 years since then, the remnant of supernova 1987A has
continued to be a focus for astronomers, providing a wealth of
information about one of the Universe’s most extreme events.
“Imaging distant astronomical objects like this at wavelengths less
than 1 cm demands the most stable atmospheric conditions. For this
telescope, these are usually only possible during cooler winter
conditions but even then, the humidity and low elevation of the site
makes things very challenging,” explained Dr Giovanna Zanardo from the
International Centre for Radio Astronomy Research, lead author of a paper accepted for publication in the Astrophysical Journal (arXiv.org version).
Unlike optical telescopes, a radio telescope can operate in the
daytime and can peer through gas and dust allowing astronomers to see
the inner workings of objects like supernova remnants, radio galaxies
and black holes.
“Supernova remnants are like natural particle accelerators, the radio
emission we observe comes from electrons spiralling along the magnetic
field lines and emitting photons every time they turn. The higher the
resolution of the images the more we can learn about the structure of
this object,” said co-author Prof Lister Staveley-Smith, also from the
International Centre for Radio Astronomy Research.
“Not only have we been able to analyze the morphology of Supernova
1987A through our high resolution imaging, we have compared it to X-ray
and optical data in order to model its likely history,” added co-author
Prof Bryan Gaensler from the University of Sydney.
The team suspects a compact source or pulsar wind nebula to be
sitting in the centre of the radio emission, implying that the supernova
explosion did not make the star collapse into a black hole. They will
now attempt to observe further into the core and see what’s there.
Bibliographic information: Giovanna
Zanardo et al. 2013. High-resolution radio observations of SNR 1987A at
high frequencies. Accepted for publication in the Astrophysical Journal; arXiv: 1301.6527
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