English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The actual value of the oxygen abundance of the metal-poor planetary nebulaPN G135.9+55.9 has frequently been debated in the literature. We wanted toclarify the situation by making an improved abundance determination based on astudy that includes both new accurate observations and new models. We madeobservations using the method of integral field spectroscopy with the PMASinstrument, and also used ultraviolet observations that were measured withHST-STIS. In our interpretation of the reduced and calibrated spectrum we usedfor the first time, recent radiation hydrodynamic models, which were calculatedwith several setups of scaled values of mean Galactic disk planetary nebulametallicities. For evolved planetary nebulae, such as PN G135.9+55.9, it turnsout that departures from thermal equilibrium can be significant, leading tomuch lower electron temperatures, hence weaker emission in collisionallyexcited lines. Based on our time-dependent hydrodynamic models and the observedemission line [OIII]5007, we found a very low oxygen content of about 1/80 ofthe mean Galactic disk value. This result is consistent with emission linemeasurements in the ultraviolet wavelength range. The C/O and Ne/O ratios areunusually high and similar to those of another halo object, BoBn-1.

The evolution of planetary nebulae VI. On the chemical composition of the metal-poor PN G135.9+55.9