Figure 12.
presence of high-velocity 56Ni in the northern region of the supernova.
Difference image
shows SN1987A light
echoes as positive and
negative (bright and
dark) circular rings.
They appear uniformly
circular because
the echo is reflected
off sheet-like dust
structures. Black boxes
mark the GMOS fields,
and red points show the
spectral locations.
Most theoretical models of supernovae require some asymmetry to explode successfully, and observations such as these obtained with Gemini South of SN1987A can
better constrain the simulations. The complete results will be published in The Astrophysical Journal, Volume 767. A link is also
now available:
http://iopscience.iop.org/0004-637X/767/1/45
tribution but also on the exact region observed. The echo spectra must be compared
to an appropriate isotropic source model,
which is based on the original SN1987A outburst observations. The well-known source
spectrum (SN1987A) is advantageous, then,
because it provides an excellent reference
for isotropic emission scenarios.
The Ha line shows some of the strongest
deviations from the isotropic assumption
(Figure 13). Two particularly interesting examples come from opposite sides of the
e