Abstract
AbstractPNe are known to be photoionized objects. However they also have low-ionization structures (LIS) with different excitation behavior. We are only now starting to answer why most LIS have lower electron densities than the PN shells hosting them, and whether or not their intense emission in low-ionization lines is the key to their main excitation mechanism. Can LIS line ratios, chemical abundances and kinematics enlight the interplay between the different excitation and formation processes in PNe? Based on the spectra of five PNe with LIS and using new diagnostic diagrams from shock models, we demonstrate that LIS’s main excitation is due to shocks, whereas the other components are mainly photoionized. We propose new diagnostic diagrams involving a few emission lines ([N II], [O III], [S II]) and fshocks/f*, where fshocks and f* are the ionization photon fluxes due to the shocks and to the central star ionizing continuum, respectively.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Proceedings of the International Astronomical Union
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
