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

Here, we present 6-9 um spectra of a sample of RNe, HII regions, YSOs,evolved stars and galaxies that show strong unidentified infrared bands,obtained with the ISO-SWS. The IR emission features show pronounced variations.1) The 6.2 um feature shifts and clearly shows profile variations. 2) The 7.7um complex is comprised of at least two subpeaks peaking at 7.6 and onelongwards of 7.7 um. In some cases the main peak can apparently shift up to 8um. Two sources do not exhibit a 7.7 um complex but instead show a broademission feature at 8.22 um. 3) The 8.6 um feature has a symmetric profile inall sources and some sources exhibit this band at slightly longer wavelengths.For the 6.2, 7.7 and 8.6 um features, the sources have been classifiedindependently based on their profile and peak position. The classes derived forthese features are directly linked with each other. Furthermore, the observed6--9 um spectrum depends on the type of object. We attribute the observed 6.2um profile and peak position to the combined effect of a PAH family andanharmonicity with pure PAHs representing the 6.3 um component andsubstituted/complexed PAHs representing the 6.2 um component. The 7.6 umcomponent is well reproduced by both pure and substituted/complexed PAHs butthe 7.8 um component remains an enigma. In addition, the exact identificationof the 8.22 um feature remains unknown. The observed variations in thecharacteristics of the IR emission bands are linked to the local physicalconditions. Possible formation and evolution processes that may influence theinterstellar PAH class are highlighted.

The rich 6 to 9 $\vec\mu$m spectrum of interstellar PAHs