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Patrice Bouchet |
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"SN 1987A:
20 Years Later" |
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Supernova SN 1987A appeared in the
LMC 20 years ago. It soon became a bonanza for Astrophysics, with a
series of “firsts” that I will review: neutrinos detection, blue
progenitor, evidence for an asymmetric explosion, important mixing
in the envelope, direct observation of explosive nucleosynthesis and
determination of abundances of the radioactive elements formed
during the explosion, detection of circum- and interstellar
material, and discovery of dust condensation in the ejecta. I will
show why studying SN 1987A is still a topical issue, at the time
when the shock wave is propagating inside the inner equatorial ring
formed during the last stages of the progenitor evolution and
destroying its dust grains, while the reverse shock propagating
inward is about to reach the outer part of the debris. We are
witnessing for the first time the birth of a remnant and still many
unknowns remain on the supernova itself: the explosion mechanism is
still not well understood and what is left at the center of the
explosion is still not known; in particular, was the progenitor star
a member of a binary system? How did the triple rings system of the
CSM form? SNR 1987A is expected to brighten at all wavelengths by a
factor 100 in the next ten years, and future observations will most
certainly be as exciting as the past ones. They should allow to
answer many open questions: in particular concerning the abundances
of the elements synthesized and the fate of the dust in the debris
after the passage of the reverse shock, which is a key issue in
order to explain the observation of large IR emission in galaxies
lying at cosmological distance. |