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Supernova 1987A remains the most well-observed and well-studied supernova todate. Observations produced excellent broad-band photometric and spectroscopiccoverage over a wide wavelength range at all epochs. Here, we focus on the veryearly spectroscopic observations. Only recently have numerical models been ofsufficient detail to accurately explain the observed spectra. In SN 1987A, goodagreement has been found between observed and synthetic spectra for day one,but by day four, the predicted Balmer lines become much weaker than theobserved lines. We present the results of work based on aradiation-hydrodynamic model by Blinnikov and collaborators. Synthetic non-LTEspectra generated from this model by the general radiation transfer codePHOENIX strongly support the theory that significant mixing of nickel into theouter envelope is required to maintain strong Balmer lines. Preliminary resultssuggest a lower limit to the average nickel mass of 1.0 \times 10^{-5} solarmasses is required above 5000 \kmps by day four. PHOENIX models thus have thepotential to be a sensitive probe for nickel mixing in the outer layers of asupernova.Comment: 16 pages, 7 figures, ApJ, v556 2001 (in press

56Ni Mixing in the Outer Layers of SN 1987A

⁵⁶Ni Mixing in the Outer Layers of SN 1987A