eprintid: 10190848 rev_number: 6 eprint_status: archive userid: 699 dir: disk0/10/19/08/48 datestamp: 2024-04-17 08:54:32 lastmod: 2024-04-17 08:54:32 status_changed: 2024-04-17 08:54:32 type: article metadata_visibility: show sword_depositor: 699 creators_name: Long, David M creators_name: Baker, Deborah creators_name: To, Andy SH creators_name: van Driel-Gesztelyi, Lidia creators_name: Brooks, David H creators_name: Stangalini, Marco creators_name: Murabito, Mariarita creators_name: James, Alexander W creators_name: Mathioudakis, Mihalis creators_name: Testa, Paola title: Identifying Plasma Fractionation Processes in the Chromosphere Using IRIS ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F63 note: Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. abstract: The composition of the solar corona differs from that of the photosphere, with the plasma thought to fractionate in the solar chromosphere according to the first ionization potential (FIP) of the different elements. This produces a FIP bias, wherein elements with a low FIP are preferentially enhanced in the corona compared to their photospheric abundance, but direct observations of this process remain elusive. Here, we use a series of spectroscopic observations of active region AR 12759 as it transited the solar disk over a period of 6 days from 2020 April 2–7 taken using the Hinode Extreme ultraviolet Imaging Spectrometer and Interface Region Imaging Spectrograph (IRIS) instruments to look for signatures of plasma fractionation in the solar chromosphere. Using the Si x/S x and Ca xiv/Ar xiv diagnostics, we find distinct differences between the FIP bias of the leading and following polarities of the active region. The widths of the IRIS Si iv lines exhibited clear differences between the leading and following polarity regions, indicating increased unresolved wave activity in the following polarity region compared to the leading polarity region, with the chromospheric velocities derived using the Mg ii lines exhibiting comparable, albeit much weaker, behavior. These results are consistent with plasma fractionation via resonant/nonresonant waves at different locations in the solar chromosphere following the ponderomotive force model, and indicate that IRIS could be used to further study this fundamental physical process. date: 2024-04-08 date_type: published publisher: American Astronomical Society official_url: http://dx.doi.org/10.3847/1538-4357/ad3234 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2268071 doi: 10.3847/1538-4357/ad3234 lyricists_name: Long, David lyricists_name: Baker, Deborah lyricists_name: James, Alexander William lyricists_id: DMLON63 lyricists_id: DBAKE94 lyricists_id: AWJAM85 actors_name: Kalinowski, Damian actors_id: DKALI47 actors_role: owner full_text_status: public publication: The Astrophysical Journal volume: 965 number: 1 article_number: 63 issn: 0004-637X citation: Long, David M; Baker, Deborah; To, Andy SH; van Driel-Gesztelyi, Lidia; Brooks, David H; Stangalini, Marco; Murabito, Mariarita; ... Testa, Paola; + view all <#> Long, David M; Baker, Deborah; To, Andy SH; van Driel-Gesztelyi, Lidia; Brooks, David H; Stangalini, Marco; Murabito, Mariarita; James, Alexander W; Mathioudakis, Mihalis; Testa, Paola; - view fewer <#> (2024) Identifying Plasma Fractionation Processes in the Chromosphere Using IRIS. The Astrophysical Journal , 965 (1) , Article 63. 10.3847/1538-4357/ad3234 <https://doi.org/10.3847/1538-4357%2Fad3234>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10190848/1/Long_Identifying%20Plasma%20Fractionation%20Processes%20in%20the%20Chromosphere%20Using%20IRIS_VoR.pdf