Speaker
Description
Optical integral field spectroscopy of planetary nebulae (PNe) provides a unique tool to explore the spatial relationships between the complex mixture of the many components -- neutral, low and high ionization gas, dust and central star -- and their underlying physical conditions. In this contribution, we highlight selected results on a detailed analysis of the optical line and continuum emission in the very high ionization Galactic PN, NGC 4361, based on MUSE commissioning data in its Wide Field (60"x60") normal (4750-9300 Å) mode. MUSE revealed weak extended [N II] emission as well as >100 spatially unresolved [NII] emitting knots, that we dubbed the "freckels". There are several linear associations of these knots but none point back convincingly to the central star. They have low-moderate ionization with Te~11000 K, Ne~1500 cm$^{-3}$, generally show higher extinction than the extended high ionization nebula and present velocity offsets in [NII] with respect to the main nebula, as traced by the velocities of Halpha emission line. The results suggests that NGC 4361 is not completely optically thin. The identified low ionization ’freckles’ do not clearly appear to diffeer in (He, N, O, S) abundance with respect to the extended high ionization gas. The spatial distribution and radial velocities of these features suggest that they belong to a thick disk oriented perpendicular to the large-scale nebular gas, perhaps remnants of an earlier structure.
