Observing Co-Located Neutral and Ionized Gas-Phase Iron Depletion in the Magellanic Clouds

@misc{li2026observing,
  title = {{Observing Co-Located Neutral and Ionized Gas-Phase Iron Depletion in the Magellanic Clouds}},
  author = {Yun Qi Li and Jessica K. Werk and Caleb R. Choban and Julia Roman-Duval and Kirill Tchernyshyov and J. Xavier Prochaska and Doyeon A. Kim and Arianna S. Long},
  howpublished = {arXiv},
  year = {2026},
  month = aug,
  doi = {10.48550/arxiv.2608.12557},
  eprint = {2608.12557},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2608.12557},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Observing Co-Located Neutral and Ionized Gas-Phase Iron Depletion in the Magellanic Clouds
AU  - Yun Qi Li
AU  - Jessica K. Werk
AU  - Caleb R. Choban
AU  - Julia Roman-Duval
AU  - Kirill Tchernyshyov
AU  - J. Xavier Prochaska
AU  - Doyeon A. Kim
AU  - Arianna S. Long
PY  - 2026
DA  - 2026/08/12
PB  - arXiv
DO  - 10.48550/arxiv.2608.12557
UR  - https://arxiv.org/abs/2608.12557
AB  - Depletion is the observed phenomenon where gas-phase elemental abundances are reduced through accretion onto dust grains. We measure neutral gas-phase elemental abundances (S, Fe) in the Magellanic Clouds along 33 sightlines using high-resolution UV spectroscopy (HST/COS and HST/STIS), and compare them to ionized gas-phase abundances (S, Fe) adopted from the literature for six co-located H\,\textsc{ii} regions (with the furthest separation of ≲3', 50 pc). Comparing S abundances show that S is minimally depleted in the H\,\textsc{ii} regions and surrounding diffuse ISM. However, we find that the gas-phase Fe abundances in H\,\textsc{ii} regions can be lower than those of the neighboring neutral ISM by 0.3 to 2 dex. This difference is likely an offset in the amount of Fe depleted into dust grains. As accretion of gas-phase Fe is likely not effective at the temperatures of the H\,\textsc{ii} regions, Fe depletion into solid form would have occurred in the dense atomic or molecular clouds prior to star formation. Stronger depletion in the H\,\textsc{ii} regions shows that Fe-bearing grains survive destruction in the first few million years following ionization. Our observations highlight that Fe depletion in H\,\textsc{ii} regions can be a useful tracer of Fe depletion in dense molecular clouds, which are challenging to observe directly via UV absorption.
ER  -