(Submitted February 11, 1997)
Do any of your programs and/or archives address the X-ray/gamma-ray
spectra of supernovae? Specifically, I am interested in determining the
isotopic abundances that might be apparent in the effluvia surrounding
supernovae and, especially, the one that occurred just a few years ago
and was visible from, say, the observatory in Chile. Do you have any
information and/or references that might be of value to me? Please
note, again, that I am interested in isotopes, not elements. The latter
would be apparent in visible spectra. Rather, I am interested in the
relative abundances of the various isotopes.
X-rays and gamma-rays can help us understand the isotopic
abundances from supernovae. However, only for particular radioactive
isotopes. Let me explain:
In a supernova explosion many elements and isotopes are created,
mostly through the rapid process (r process). However, most of these
are unstable so they decay down to a stable or more stable isotope. It
is during this decay process that they give off gamma-rays. The energy
of the gamma-ray will depend on the particular isotope and the process
involved. These gamma-rays are observed as spectral lines within the
Now a word about 1/2 life. The 1/2 life of a particular isotope
is the time it takes for half of the initial quantity of the isotope to
decay. So, observing a supernovae early on one can observe a number of
these spectral lines, however over time they fade as there become fewer
radioactive isotopes and more stable isotopes.
For example, the element Titanium 44 decays with a 1/2 life of about
70 years. The decay process gives off 1 MeV, 60 and 70 keV photons.
By counting these photons, the mass of Ti 44 produced in the supernova
explosion can be estimated.
Thank you for your question. As far as particular details of the
supernova 1987A, I suggest that you do a literature search on this topic
in the leading astronomical journals. This can be easily done online
from the URL http://adsabs.harvard.edu/ (http://adsabs.harvard.edu/abstract_service.html)
(for Imagine the Universe!)