The case of NGC 6302: The impact of shocks in the derivation of Nitrogen abundances

Abstract: High nitrogen abundance is characteristic of Type I planetary nebulae as well as their highly filamentary structure. In the present work we test the hypothesis of shocks as a relevant excitation mechanism for a Type-I nebula, NGC 6302, using recently released diagnostic diagrams to distinguish shocks from photoexcitation. The construction of diagrams depends on emission line ratios and kinematical information. NGC 6302 shows the relevance of shocks in peripheral regions and the importance to the whole nebula. Using shocks, we question the usual assumption of ICF calculation, justifying a warning to broadly used abundance derivation methods. From a kinematical analysis, we derive a new distance for NGC 6302 of $805\pm143\,$ pc.