Prof Patrick Roche

Abstract:

Spectra of SN1987A in the 10-micron region taken on days 257 and 366-371 after core collapse are presented. The hydrogen/helium envelope is partially ionized at the few percent level and this provides the free-free continuum and hydrogenic lines. There is relative transparency in the midinfrared, while the bound electrons provide the X-ray opacity which is still considerable at day 370. The continuum appears to have become optically thin from about 6 months, and there may be a contribution from low ionization middle mass elements and the iron group. Apart from an excess between 8-9 microns which has been tentatively attributed to molecular SiO, there is no evidence of departure from the emission expected from an optically thin plasma, and no sign of any emission from dust.