Mapping Wolf-Rayet winds with spectro-interferometry I. Detection of multiple co-rotating interaction regions in WR 6
Abstract
WR 6 is the prototype for periodic variability due to large-scale wind structures in Wolf-Rayet (WR) stars, showing a consistent periodicity of 3.76 d in photometry, spectroscopy, and polarimetry. However, the origin of this variability is debated, attributed either to corotating interaction regions (CIRs) or a low-mass companion. We use time-resolved interferometry to investigate the origin of periodic variability in WR 6. We aim to detect and characterize structures in the stellar winds of WR 6 and discriminate between the CIR and low-mass companion scenarios. Using the extended configuration of the Auxiliary Telescopes at VLTI, we obtained six GRAVITY epochs over six months to search for the presence and variability of wind-structures in WR 6. We also obtained complementary spectroscopic observations during one of the epochs to monitor contemporaneous spectral line variability. For all six epochs of GRAVITY observations: (i) WR 6 is consistent with a single star and has no spatially resolved companion detected above M≳6 M⊙; (ii) The He I line-emitting region is spatially resolved, while the He II lines remain unresolved, consistent with atmosphere models; (iii) Around 2.19 μm, discrete line-emitting features offset from the center of the star are detected. The number, positions, and wavelengths of these features vary across epochs. Spectroscopic monitoring reveals spectral line residuals that broadly correspond to the two features seen in the GRAVITY data of the fifth epoch. Finally, the first three epochs, observed on three consecutive nights, show significant variability in these features but cannot be directly linked across epochs. We thus report the detection of multiple large-scale structures in the wind of WR 6 with VLTI/GRAVITY. We favor CIRs as their likely origin owing to temporal and spatial variability that cannot be reconciled with a low-mass companion.
Related
- First Very Long Baseline Interferometry Fringe Detection at 690GHz
- Probing the magnetic fields of starspots with transit mapping. II. Signatures of star-planet interaction
- Dynamical plausibility of triple-assisted interaction in Be-star multiple systems
- Dynamical plausibility of triple-assisted interaction in Be-star multiple systems
- Globular cluster formation with multiple stellar populations: A comprehensive overview of a star-cloud interaction scenario
BibTeX
@misc{deshmukh2026mapping,
title = {{Mapping Wolf-Rayet winds with spectro-interferometry I. Detection of multiple co-rotating interaction regions in WR 6}},
author = {K. Deshmukh and A. -N. Chené and A. J. Frost and T. De Prins and L. Fabiani and H. Sana and R. R. Lefever and A. Mérand and N. D. Richardson and A. A. C. Sander and T. Shenar},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.14348},
eprint = {2610.14348},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.14348},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Mapping Wolf-Rayet winds with spectro-interferometry I. Detection of multiple co-rotating interaction regions in WR 6
AU - K. Deshmukh
AU - A. -N. Chené
AU - A. J. Frost
AU - T. De Prins
AU - L. Fabiani
AU - H. Sana
AU - R. R. Lefever
AU - A. Mérand
AU - N. D. Richardson
AU - A. A. C. Sander
AU - T. Shenar
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2610.14348
UR - https://arxiv.org/abs/2610.14348
AB - WR 6 is the prototype for periodic variability due to large-scale wind structures in Wolf-Rayet (WR) stars, showing a consistent periodicity of 3.76 d in photometry, spectroscopy, and polarimetry. However, the origin of this variability is debated, attributed either to corotating interaction regions (CIRs) or a low-mass companion. We use time-resolved interferometry to investigate the origin of periodic variability in WR 6. We aim to detect and characterize structures in the stellar winds of WR 6 and discriminate between the CIR and low-mass companion scenarios. Using the extended configuration of the Auxiliary Telescopes at VLTI, we obtained six GRAVITY epochs over six months to search for the presence and variability of wind-structures in WR 6. We also obtained complementary spectroscopic observations during one of the epochs to monitor contemporaneous spectral line variability. For all six epochs of GRAVITY observations: (i) WR 6 is consistent with a single star and has no spatially resolved companion detected above M≳6 M_⊙; (ii) The He I line-emitting region is spatially resolved, while the He II lines remain unresolved, consistent with atmosphere models; (iii) Around 2.19 μm, discrete line-emitting features offset from the center of the star are detected. The number, positions, and wavelengths of these features vary across epochs. Spectroscopic monitoring reveals spectral line residuals that broadly correspond to the two features seen in the GRAVITY data of the fifth epoch. Finally, the first three epochs, observed on three consecutive nights, show significant variability in these features but cannot be directly linked across epochs. We thus report the detection of multiple large-scale structures in the wind of WR 6 with VLTI/GRAVITY. We favor CIRs as their likely origin owing to temporal and spatial variability that cannot be reconciled with a low-mass companion.
ER -