Redshifted Cool Gas in the Disturbed H i Disk of the Starburst Dwarf NGC 4214
Abstract
We report redshifted cool gas toward the central star-forming region of the nearby starburst dwarf galaxy NGC 4214. Hubble Space Telescope/Cosmic Origins Spectrograph (COS) spectra show low-ionization absorbers redshifted relative to the systemic velocity, most clearly in S ii (Δ v = 19.8 ± 2.6 km s ⁻¹ ) and supported by Mg ii (Δ v = 30.3 ± 3.0 km s ⁻¹ ), while P ii remains tentative (Δ v = 7.5 ± 3.4 km s ⁻¹ ). The Keck/HIRES spectra also reveal a redshifted Ca ii absorption component (Δ v = 25.6 ± 1.5 km s ⁻¹ ). Because the absorption is detected against the central UV or optical continuum, the gas must lie in the foreground of the star-forming region and be moving away from the observer and toward the background UV source in projection. A Very Large Array (VLA)–THINGS H i spectrum extracted at the COS position within one VLA beam also shows a redshifted neutral component at v hel = 329.2 ± 0.9 km s ⁻¹ , offset by 38.2 ± 1.3 km s ⁻¹ from systemic and by 27.6 ± 1.0 km s ⁻¹ from the dominant local H i component. The FAST H i mapping further reveals an extended, kinematically disturbed neutral disk, with residual structures relative to a warped-disk model. Together, the redshifted UV absorption, the redshifted H i component, and the disturbed large-scale H i velocity field show that the central anomalous cool gas is observed in a galaxy with a disturbed extended neutral disk. This geometry suggests that the redshifted cool gas may trace inflow or recycled fallback toward the central region, although warped-disk or noncircular disk motions cannot be fully excluded.
Versions
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BibTeX
@article{yan2026redshifted,
title = {{Redshifted Cool Gas in the Disturbed H i Disk of the Starburst Dwarf NGC 4214}},
author = {Shulan Yan and 淑澜 鄢 and Taotao Fang and 陶陶 方 and Xiaochuan Jiang and 小川 姜 and Junfeng Wang and 俊峰 王 and Qingzheng Yu and 清正 余 and Chuanpeng Zhang and 传朋 张 and Ming Zhu and 明 朱},
journal = {The Astrophysical Journal Letters},
year = {2026},
month = nov,
doi = {10.3847/2041-8213/aeb26b},
url = {https://iopscience.iop.org/article/10.3847/2041-8213/aeb26b},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Redshifted Cool Gas in the Disturbed H i Disk of the Starburst Dwarf NGC 4214
AU - Shulan Yan
AU - 淑澜 鄢
AU - Taotao Fang
AU - 陶陶 方
AU - Xiaochuan Jiang
AU - 小川 姜
AU - Junfeng Wang
AU - 俊峰 王
AU - Qingzheng Yu
AU - 清正 余
AU - Chuanpeng Zhang
AU - 传朋 张
AU - Ming Zhu
AU - 明 朱
PY - 2026
DA - 2026/11/03
JO - The Astrophysical Journal Letters
DO - 10.3847/2041-8213/aeb26b
UR - https://iopscience.iop.org/article/10.3847/2041-8213/aeb26b
AB - We report redshifted cool gas toward the central star-forming region of the nearby starburst dwarf galaxy NGC 4214. Hubble Space Telescope/Cosmic Origins Spectrograph (COS) spectra show low-ionization absorbers redshifted relative to the systemic velocity, most clearly in S ii (Δ v = 19.8 ± 2.6 km s ⁻¹ ) and supported by Mg ii (Δ v = 30.3 ± 3.0 km s ⁻¹ ), while P ii remains tentative (Δ v = 7.5 ± 3.4 km s ⁻¹ ). The Keck/HIRES spectra also reveal a redshifted Ca ii absorption component (Δ v = 25.6 ± 1.5 km s ⁻¹ ). Because the absorption is detected against the central UV or optical continuum, the gas must lie in the foreground of the star-forming region and be moving away from the observer and toward the background UV source in projection. A Very Large Array (VLA)–THINGS H i spectrum extracted at the COS position within one VLA beam also shows a redshifted neutral component at v hel = 329.2 ± 0.9 km s ⁻¹ , offset by 38.2 ± 1.3 km s ⁻¹ from systemic and by 27.6 ± 1.0 km s ⁻¹ from the dominant local H i component. The FAST H i mapping further reveals an extended, kinematically disturbed neutral disk, with residual structures relative to a warped-disk model. Together, the redshifted UV absorption, the redshifted H i component, and the disturbed large-scale H i velocity field show that the central anomalous cool gas is observed in a galaxy with a disturbed extended neutral disk. This geometry suggests that the redshifted cool gas may trace inflow or recycled fallback toward the central region, although warped-disk or noncircular disk motions cannot be fully excluded.
SN - 2041-8213
SN - 2041-8205
ER -