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.
Authors
- Taotao Fang (ORCID: https://orcid.org/0000-0002-2853-3808)
- Chuanpeng Zhang
- Jiang Xiaochuan
- Junfeng Wang
- Shulan Yan
- Ming Zhu
- Qingzheng Yu
Institutions
- Xiamen University (CN)
- Chinese Academy of Sciences (CN)
- Arcetri Astrophysical Observatory (IT)
- Fujian Business University (CN)
- National Astronomical Observatories (CN)
- University of Florence (IT)
- National Institute for Astrophysics (IT)
Publication Details
- Journal
- The Astrophysical Journal Letters
- Published
- 2026-11-03
- DOI
- https://doi.org/10.3847/2041-8213/aeb26b
- Primary Topic
- Galaxies: Formation, Evolution, Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Space Telescope Science Institute
- National Natural Science Foundation of China
- Department of Education, Fujian Province
- National Astronomical Observatories, Chinese Academy of Sciences