Microstructures of planetary nebulae with large telescopes.pdfVIP

Microstructures of Planetary Nebulae with Large Telescopes Denise R. Gonçalves 5 Insituto de Astrofísica de Canarias, Tenerife, Spain 0 Instituto de Astronomia, Geofísica e Ciências Atmosféricas - USP, São Paulo, Brazil 0 2 Abstract. Planetary nebulae (PNe) are known to possess a variety of small-scale structures that v o are usually in a lower ionization state than the main body of the nebulae. The morphological and N kinematic properties of these low-ionization structures (LISs) vary from type to type in the sense that LISs can appear in the form of pairs of knots, filaments, jets, and isolated features moving with 3 velocities that either do not differ substantially from that of the ambient nebula, or instead move supersonically through the environment. The high-velocity jets and pairs of knots, also known as 1 FLIERs, are likely to be shock-excited. So far, most of the FLIERs analyzed with ground-based v small and medium telescopes, as well as with the HST, do not show the expected shock-excited 9 0 features —either the bow-shock geometry or the shock excited emission lines. In this talk we discuss 1 the crucial problem of the excitation mechanisms of FLIERs —through the comparison of jets and 1 knots of NGC 7009 and K 4-47— and what might be the contribution of large telescopes. 1 5 0 / MACRO- AND MICROSTRUCTURES OF PNE h p - The main, macro, structures of PNe are the elliptical, bipolar, or point-symmetric rims o r and shells, as well the haloes that dominate the optical [O III] and Hα line emi