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VII Zw031

Ground-based optical images have been used to suggest that VIIZw031 might be an elliptical galaxy (eg. Djorgovski et al. 1990; Sanders & Mirabel 1996); however, the NICMOS images clearly resolve extremely bright, asymmetric spiral arms in the nucleus. Numerous clusters are seen in the galactic disk and the reddening peaks to the east of the nucleus. While the NICMOS data clearly imply that this is a spiral system and strengthens the view that the progenitors of LIGs and ULIGs are composed of at least one spiral galaxy, it is not obvious what triggered the activity occuring in VIIZw031. There is no evidence to date of a nearby interacting companion galaxy (pre-merger) or tidal tail remnants (post-merger).

VII Zw031

Shaded contour plots of the extinction corrected 2.2 µm emission are shown together with the 1.1 µm (upper left) observed emission. In both panels, the contours and shading are logarithmic with the contours spaced by factors 21/2. (The level values are the same as for the figure above). The arcsec displacements in RA and DEC, given along the borders are measured from the 2.2 µm in all frames. At the upper left, a length bar is drawn. For the ratio image, both the 2.2 and 1.1 µm images were smoothed with the same adaptive smoothing and then smoothed with a Gaussian FWHM = 0.2" in calculating the 2.2 µm opacity from Eq. 3 (see text). In cases where a strong point-source or variable background contaminated the 2.2 µm image, the extinction corrected image was derived for 1.6 µm. For the galaxies with strong point-sources, the PSF was fit to the source and then subtracted and replaced by a Gaussian with the proper integrated flux (see text - NGC 7469, IRAS 08572+3915, IRAS 05189-2524, PKS 1345+12, IRAS 07598+6508, Mrk 1014 and 3C48).

VII Zw031

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