Two holes were drilled to depths greater than 300m in the Antarctic ice sheet, near Cape Folger on the Law Dome. The holes underwent considerable closure below 250m with localized strain-rates as high as 1 to 1.5×10−6 s−1. The closure observed in holes was non-uniform and occurred in zones 0.5 to 3 m wide. These Zones parallel the flow plane in the ice mass and are associated with a distinct domainal structure. High-closure zones are characterized by interlocking and irregular-shaped ice grains with many sub-horizontal c-axes and only occasional c-axis clusters at a high angle to the flow plane. Low-closure zones contain tabular grains with the long dimension parallel to the flow plane, abundant deformation features and a predominance of c-axes oriented at a high angle to the flow plane. The relationship between closure rate and c-axis fabric is attributed to marked plastic flow by intracrystalline slip on the basal plane to produce higher closure in areas where there is a greater variation in c-axis orientation. This deformation is attributable to overburden pressure and hence is related to depth, and is independent of shear within the main body of the ice mass.

SN1987A is the best-studied core-collapse supernova in the sky. We know what the progenitor was, what the circumstellar environment was, and what the explosion looked like over a broad electromagnetic bandpass and in neutrinos. For over a decade, the Chandra X-ray Observatory has been monitoring SN1987A on a regular basis, obtaining resolved images of the developing interaction with the circumstellar material, as well as high resolution grating spectroscopy of the X-ray emission. We highlight the latest results from this campaign and discuss the overall picture of the remnant's structure that emerges from these observations.

I describe and interpret observations of the rapidly developing impact of the debris of SN1987A with its circumstellar ring.

In 1996, the blast wave from Supernova 1987A began to strike the inner circumstellar ring, causing the appearance of “hot spots” on the ring. This event marks the birth of the supernova remnant, SNR1987A, defined as the epoch when the light of the event is dominated by interaction of the expanding debris of the supernova with its circumstellar matter.

The nebular spectra of supernovae differ from those of better-known emission nebulae in that many of the emission lines are optically thick. Here we sketch the theory for interpreting such spectra, and show how it can be used to interpret prominent emission line systems in the spectrum of SN 1987A. As examples, we describe: (1) a simple method to infer the density of OI from observations of the evolution of the doublet ratio in [O I]λλ6300; (2) new kind of hydrogen recombination hne spectrum; (3) an analysis showing that the Call infrared emission lines must come from primordial, not newly-synthesized, calcium; (4) a theory for the Fe/Co/Ni emission lines that shows that the inner envelope of SN 1987A must have a foamy texture, in which low density radioactive bubbles of Fe/Co/Ni reside in a massive substrate of hydrogen, helium, and other elements.