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/

Zendy Plus

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

Zendy Tools

Zendy Open

The formation of low emission lines in quasars and active galactic nuclei isstill an open issue. Aided by the organizing power of the 4D eigenvector 1scheme, we review basic developments since the 1980s, devoting specialattention to the CaII IR triplet and the OI 8446 emission lines. Coverage ofthese lines is cumbersome since they are shifted in an inconvenient IR domainalready at modest redshifts (~ 0.2). Their detection is also difficult sincethey are faint and often buried in the Ca II absorption of the host galaxy. Wediscuss how these lines can provide unambiguous constraints on the physicalconditions of the broad line emitting regions of quasars when detected inemission, and summarise preliminary results for a sample of luminous,intermediate redshift quasars.

Low Ionization Emission Lines in Quasars: Clues from OI 8446 and the CaII Triplet