WFPC2 Imaging of NGC6543: Closing in on Bubbles, Shocks, and Precessing Jets

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Session 90 -- Planetary Nebula and Degenerate Stars
Oral presentation, Wednesday, 11, 1995, 10:00am - 11:30am

[90.03] WFPC2 Imaging of NGC6543: Closing in on Bubbles, Shocks, and Precessing Jets

J. P. Harrington (U Md), K.J. Borkowski (U Md and GSFC)

The planetary nebula NGC6543 is one of the most complex known. It exhibits "helical" structures and a complex velocity field, both with a high degree of point symmetry, fast low ionization emission regions ("FLIERs"), and a high velocity jet. This nebula is also known to have extended X-ray emission.

We have used the HST WFPC2 narrow-band filters to image NGC6543 in ten emission lines. The high spatial resolution clarifies the geometrical structure and reveals a wealth of new detail, while the line-ratio maps elucidate the physical processes. The innermost structure is clearly a highly ionized ellipsoidal (8\arcsec $\times$ 11.\arcsec 5) bubble, blown by the wind of the Wolf-Rayet central star, whose ends seem to have burst. A ring of low-excitation knots, 16.\arcsec 5 in diameter, girds this ellipsoid in the plane perpendicular to its long axis. A pair of sharply-defined spherical bubbles appear to emerge from this ring, encompassing the ellipsoid. Two low-ionization arcs ( the "polar caps") cross the outer surfaces of the spherical bubbles. Further out are the "ansae" or "polar condensations", which show clear signs of hydrodynamic instabilities. Finally, we see many long ($\sim$ 8\arcsec ), narrow ($<0.\arcsec 5$) radial features which are strong evidence for a precessing jet. Our maps of the [N II] /H$\alpha$ and H$\alpha$/H$\beta$ line ratios show evidence of shock excitation. The shocks are localized along the polar caps, and also especially at the leading surfaces of the ansae and where the jets strike low-ionization clumps.

Along with PC images of the core, the WF camera obtained images of the outer halo. We are able to resolve the ionization structure in the brightest filaments and thus address the shock-heating mechanisms proposed to explain the elevated temperatures seen there.

Based on observations with the NASA/ESA Hubble Space Telescope, obtained at STScI, operated by AURA under NASA contract NAS5-26555. Supported by NASA through grant GO-5403.01-93A from STScI.

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