The highly magnetic Wolf-Rayet binary HD 45166 resolved with VLTI/GRAVITY
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| Format: | Preprint |
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2025
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| author | Deshmukh, K. Shenar, T. Mérand, A. Sana, H. Marchant, P. Wade, G. A. Bodensteiner, J. Chené, A. -N. Frost, A. J. Gilkis, A. Langer, N. Oskinova, L. |
| author_facet | Deshmukh, K. Shenar, T. Mérand, A. Sana, H. Marchant, P. Wade, G. A. Bodensteiner, J. Chené, A. -N. Frost, A. J. Gilkis, A. Langer, N. Oskinova, L. |
| contents | HD 45166 was recently reported to be a long-period binary comprising a B7V star and a highly magnetic ($\langle B \rangle = 43.0\pm0.5\,$kG) hot Wolf-Rayet-like component, dubbed as a quasi Wolf-Rayet (qWR) star in literature. While originally proposed to be a short-period binary, long-term spectroscopic monitoring suggested a 22.5 yr orbital period. With a derived dynamical mass of $2.03\pm0.44\,M_\odot$, the qWR component is the most strongly magnetized non-degenerate object ever detected and a potential magnetar progenitor. However, the long period renders the spectroscopic orbital solution and dynamical mass estimates uncertain, casting doubts on whether the qWR component is massive enough to undergo core-collapse. Here, we spatially resolve the HD 45166 binary using newly acquired interferometric data obtained with the GRAVITY instrument of the Very Large Telescope Interferometer. Due to the calibrator star being a binary as well, we implement a new approach for visibility calibration and test it thoroughly using archival GRAVITY data. The newly calibrated HD 45166 data reveal the unmistakable presence of a companion to the qWR component with an angular separation of $10.9\pm0.1$ mas (which translates to a projected physical separation of $10.8\pm0.4$ au), consistent with the long-period orbit. We obtain a model-independent qWR mass $M_{\rm qWR} = 1.96^{+0.74}_{-0.54}\,M_\odot$ using interferometric and spectroscopic data together. This observation robustly confirms that HD 45166 is truly a long-period binary, and provides an anchor point for accurate mass determination of the qWR component with further observations. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_00981 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The highly magnetic Wolf-Rayet binary HD 45166 resolved with VLTI/GRAVITY Deshmukh, K. Shenar, T. Mérand, A. Sana, H. Marchant, P. Wade, G. A. Bodensteiner, J. Chené, A. -N. Frost, A. J. Gilkis, A. Langer, N. Oskinova, L. Solar and Stellar Astrophysics Instrumentation and Methods for Astrophysics HD 45166 was recently reported to be a long-period binary comprising a B7V star and a highly magnetic ($\langle B \rangle = 43.0\pm0.5\,$kG) hot Wolf-Rayet-like component, dubbed as a quasi Wolf-Rayet (qWR) star in literature. While originally proposed to be a short-period binary, long-term spectroscopic monitoring suggested a 22.5 yr orbital period. With a derived dynamical mass of $2.03\pm0.44\,M_\odot$, the qWR component is the most strongly magnetized non-degenerate object ever detected and a potential magnetar progenitor. However, the long period renders the spectroscopic orbital solution and dynamical mass estimates uncertain, casting doubts on whether the qWR component is massive enough to undergo core-collapse. Here, we spatially resolve the HD 45166 binary using newly acquired interferometric data obtained with the GRAVITY instrument of the Very Large Telescope Interferometer. Due to the calibrator star being a binary as well, we implement a new approach for visibility calibration and test it thoroughly using archival GRAVITY data. The newly calibrated HD 45166 data reveal the unmistakable presence of a companion to the qWR component with an angular separation of $10.9\pm0.1$ mas (which translates to a projected physical separation of $10.8\pm0.4$ au), consistent with the long-period orbit. We obtain a model-independent qWR mass $M_{\rm qWR} = 1.96^{+0.74}_{-0.54}\,M_\odot$ using interferometric and spectroscopic data together. This observation robustly confirms that HD 45166 is truly a long-period binary, and provides an anchor point for accurate mass determination of the qWR component with further observations. |
| title | The highly magnetic Wolf-Rayet binary HD 45166 resolved with VLTI/GRAVITY |
| topic | Solar and Stellar Astrophysics Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2503.00981 |