<?xml version="1.0" encoding="utf-8" standalone="yes"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>R.~A. Riffel |</title><link>https://mrkrmh.github.io/authors/r.~a.-riffel/</link><atom:link href="https://mrkrmh.github.io/authors/r.~a.-riffel/index.xml" rel="self" type="application/rss+xml"/><description>R.~A. Riffel</description><generator>HugoBlox Kit (https://hugoblox.com)</generator><language>en-us</language><lastBuildDate>Wed, 01 Oct 2025 00:00:00 +0000</lastBuildDate><item><title>Metallicity of active galactic nuclei from ultraviolet and optical emission lines ─ II. Revisiting the C43 metallicity calibration and its implications</title><link>https://mrkrmh.github.io/publication/2025-mnras-542-3181-d/</link><pubDate>Wed, 01 Oct 2025 00:00:00 +0000</pubDate><guid>https://mrkrmh.github.io/publication/2025-mnras-542-3181-d/</guid><description/></item><item><title>Chemical abundances in Seyfert galaxies - X. Sulphur abundance estimates</title><link>https://mrkrmh.github.io/publication/2023-mnras-521-1969-d/</link><pubDate>Mon, 01 May 2023 00:00:00 +0000</pubDate><guid>https://mrkrmh.github.io/publication/2023-mnras-521-1969-d/</guid><description/></item><item><title>Chemical abundances in Seyfert galaxies - IX. Helium abundance estimates</title><link>https://mrkrmh.github.io/publication/2022-mnras-514-5506-d/</link><pubDate>Mon, 01 Aug 2022 00:00:00 +0000</pubDate><guid>https://mrkrmh.github.io/publication/2022-mnras-514-5506-d/</guid><description/></item><item><title>Chemical abundances in Seyfert galaxies - VII. Direct abundance determination of neon based on optical and infrared emission lines</title><link>https://mrkrmh.github.io/publication/2021-mnras-508-371-a/</link><pubDate>Mon, 01 Nov 2021 00:00:00 +0000</pubDate><guid>https://mrkrmh.github.io/publication/2021-mnras-508-371-a/</guid><description/></item><item><title>Chemical abundances in Seyfert galaxies - V. The discovery of shocked emission outside the AGN ionization axis</title><link>https://mrkrmh.github.io/publication/2021-mnras-501-l-54-r/</link><pubDate>Mon, 01 Feb 2021 00:00:00 +0000</pubDate><guid>https://mrkrmh.github.io/publication/2021-mnras-501-l-54-r/</guid><description/></item></channel></rss>