SN 1987A Deconvolved by Mim

Extract

Modelling of PNs from blurred images, as from the Hubble Space Telescope, needs good deconvolution, and the better that is, the more reliable are the results. As an example, we have MIM-deconvolved the HST image of SN 1987A taken in August 1990 by the FOC in [O III] λ5007 Å (F501N). MIM (minimum information method) is a linear deconvolution method with a local smoothness constraint (Pfleiderer 1991). Our results are similar to those already published (Jakobson et al. 1991, Panagia et al. 1991) but we were able to decrease some of the uncertainties. The ring, centered on the SN, has diameter 1680 ± 20 mas (≡ 1.3 ly) and tilt 44.5°±1.5° (Fig 1.). The lumps deviate from the ellipse by up to ≤ 0.05 ly, the ratio of brightest to faintest knots being ≈ 10 (Fig.3). The SN is resolved (Fig.2), being not a uniformly illuminated disk but brighter in the center. Its FWHM is 100 ± 10 mas, i.e. an average expansion velocity since the explosion of v ≈ 3 500 km s⁻¹.