Probing Thin Winds in Massive OB Stars of the SMC with JWST/NIRSPEC Br<i>α</i> Spectroscopy
Abstract Mass loss is a key physical process in the evolution of massive stars, the impact of which propagates into galactic evolution, population synthesis models, the interpretation of high-redshift galaxies, and explosive events such as supernovae. However, there are currently substantial uncertainties in the low-metallicity, low-luminosity thin wind regime where classical diagnostics (H α and ultraviolet, UV, P Cygni profiles) yield wind momenta that are 1 to 2 orders of magnitude below prescriptions implemented by default in most evolutionary models. Here, we present spectra of the mass-loss diagnostic line Br α in 15 OB-type stars in the Small Magellanic Cloud obtained using the Near Infrared Spectrograph on the James Webb Space Telescope. The line profile morphology, recovered by virtue of the outstanding signal-to-noise ratio of the data and the avoidance of regions with nebular emission, is consistent with predictions based on previous mass-loss rate estimates from optical and UV spectroscopy. Moreover, an initial spectroscopic analysis of sources covering the thin wind regime confirms the low mass-loss rates, indicates a change of slope in the wind-momentum–luminosity relation in this regime with respect to high-luminosity objects, and strengthens the abovementioned discrepancies with commonly used wind-momentum prescriptions.
Authors
- J. O. Sundqvist (ORCID: https://orcid.org/0000-0003-1729-1273)
- J.‐C. Bouret (ORCID: https://orcid.org/0000-0003-4946-2591)
- J. Puls (ORCID: https://orcid.org/0000-0002-0874-1669)
- A. W. Fullerton (ORCID: https://orcid.org/0000-0003-2429-7964)
- D. J. Lennon (ORCID: https://orcid.org/0000-0003-3063-4867)
- F. Najarro (ORCID: https://orcid.org/0000-0002-9124-0039)
- A. Herrero (ORCID: https://orcid.org/0000-0001-8768-2179)
- M. M. Rubio-Díez (ORCID: https://orcid.org/0000-0003-4076-7313)
- F. Tramper (ORCID: https://orcid.org/0000-0001-8631-7700)
- S. Simón‐Díaz (ORCID: https://orcid.org/0000-0003-1168-3524)
- M. García (ORCID: https://orcid.org/0000-0003-0316-1208)
- D. J. Hillier (ORCID: https://orcid.org/0000-0001-5094-8017)
- C. J. Evans (ORCID: https://orcid.org/0009-0005-7288-6407)
- Margaret M. Hanson (ORCID: https://orcid.org/0000-0003-1780-6150)
- Alexandre Legault (ORCID: https://orcid.org/0000-0003-2372-9825)
Institutions
- Centre National de la Recherche Scientifique (FR)
- Space Telescope Science Institute (US)
- Universidad de La Laguna (ES)
- University of Pittsburgh (US)
- Aix-Marseille Université (FR)
- LMU Klinikum (DE)
- Université Bourgogne Franche-Comté (FR)
- Centro de Astrobiología (ES)
- Instituto de Astrofísica de Canarias (ES)
- University of Cincinnati (US)
- Universidad Autónoma de Madrid (ES)
- Ludwig-Maximilians-Universität München (DE)
- KU Leuven (BE)
Publication Details
- Journal
- The Astrophysical Journal Letters
- Published
- 2025-08-29
- DOI
- https://doi.org/10.3847/2041-8213/adfa0f
- Primary Topic
- Stellar, planetary, and galactic studies
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Aeronautics and Space Administration
- Comunidad de Madrid
- Space Telescope Science Institute
- Ministerio de Ciencia, Innovación y Universidades
- Ministerio de Ciencia e Innovación
- European Regional Development Fund
- Agencia Estatal de Investigación