How unique is Plaskett’s star? A search for organized magnetic fields in short period, interacting or post-interaction massive binary systems

Nazé, Yaël; Neiner, C.; Grunhut, J.; Bagnulo, S.; Alécian, E.; Rauw, Grégor; Wade, G. A.

doi:10.1093/mnras/stx194

Cited by 6 publications

(3 citation statements)

References 57 publications

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“…While few magnetic stars have been found in close (< 30 d) interacting or post-interaction O-star binaries (e.g. Nazé et al 2015b), the presence of distant companions is not unusual. Amongst the Of?p stars, HD 191 612 has an orbital period of about 1542 days, whilst its rotational period is 537.6 days.…”

Section: Radial Velocitiesmentioning

confidence: 99%

Diving into the magnetosphere of the Of?p star HD 108

Rauw

Nazé

ud‐Doula

et al. 2023

Monthly Notices of the Royal Astronomical Society

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We analyse optical and X-ray spectroscopy of the Of?p star HD 108, known for its strong dipolar magnetic field and its optical line profile variability with a timescale of 54 ± 3 yrs, interpreted as the stellar rotation period. Optical emission lines have now recovered from their minimum emission state reached in 2007–2008. The variations of the equivalent width of the Hα emission provide constraints on the inclination of the rotation axis (i) and the obliquity of the magnetic axis (β). The best agreement between model and observations is found for (i, β) pairs with i + β ≃ 85○ and i ∈ [30○, 55○]. The Balmer emission lines display stochastic variability at the ∼5 per cent level on timescales of a few days. TESS photometry unveils transient modulations on similar timescales in addition to prominent red noise variations. A Chandra X-ray observation of December 2021, when the star was at a higher emission level, indicates a slight increase of the flux and a spectral hardening compared to the August 2002 XMM-Newton observation, taken near minimum emission state. Magnetohydrodynamic simulations are used to compute synthetic X-ray spectra. With our current best estimate of the $\dot{M}_{B=0}$ mass-loss rate, the simulated X-ray luminosity and spectral energy distribution agree very well with the observations. Finally, the radial velocities vary on a period of 8.5 years with a peak-to-peak amplitude of 10–11 km s−1, suggesting orbital motion with an unseen companion of at least 4 M⊙.

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Section: Radial Velocitiesmentioning

confidence: 99%

Diving into the magnetosphere of the Of?p star HD 108

Rauw

Nazé

ud‐Doula

et al. 2023

Monthly Notices of the Royal Astronomical Society

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“…In particular, Ferrario et al (2009), Schneider et al (2016) suggested that large-scale magnetism among massive stars originates in mergers. Because of the presence of a magnetic field in one component of Plaskett's star, close binary interactions were also thought to be possible generators, but this assumption was discarded based on actual observations (Nazé et al 2017).…”

Section: Incidence Of Magnetismmentioning

confidence: 99%

The IACOB project

Britavskiy

Holgado

Burssens

et al. 2023

A&A

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Context. The empirical distribution of projected rotational velocities (v sin i) in massive O-type stars is characterised by a dominant slow velocity component and a tail of fast rotators. It has been proposed that binary interaction plays a dominant role in the formation of this tail. Aims. We perform a complete and homogeneous search for empirical signatures of binarity in a sample of 54 fast-rotating stars with the aim of evaluating this hypothesis. This working sample has been extracted from a larger sample of 415 Galactic O-type stars that covers the full range of v sin i values. Methods. We used new and archival multi-epoch spectra in order to detect spectroscopic binary systems. We complemented this information with Gaia proper motions and TESS photometric data to aid in the identification of runaway stars and eclipsing binaries, respectively. We also benefitted from additional published information to provide a more complete overview of the empirical properties of our working sample of fast-rotating O-type stars. Results. The identified fraction of single-lined spectroscopic binary (SB1) systems and apparently single stars among the fast-rotating sample is ∼18% and ∼70%, respectively. The remaining 12% correspond to four secure double-line spectroscopic binaries (SB2) with at least one of the components having a v sin i > 200 km s−1 (∼8%), along with a small sample of 2 stars (∼4%) for which the SB2 classification is doubtful: these could actually be single stars with a remarkable line-profile variability. When comparing these percentages with those corresponding to the slow-rotating sample, we find that our sample of fast rotators is characterised by a slightly larger percentage of SB1 systems (∼18% vs. ∼13%) and a considerably smaller fraction of clearly detected SB2 systems (8% vs. 33%). Overall, there seems to be a clear deficit of spectroscopic binaries (SB1+SB2) among fast-rotating O-type stars (∼26% vs. ∼46%). On the contrary, the fraction of runaway stars is significantly higher in the fast-rotating domain (∼33–50%) than among those stars with v sin i < 200 km s−1. Lastly, almost 65% of the apparently single fast-rotating stars are runaways. As a by-product, we discovered a new over-contact SB2 system (HD 165921) and two fast-rotating SB1 systems (HD 46485 and HD 152200) Also, we propose HD 94024 and HD 12323 (both SB1 systems with a v sin i < 200 km s−1) as candidates for hosting a quiescent stellar-mass black hole. Conclusions. Our empirical results seem to be in good agreement with the assumption that the tail of fast-rotating O-type stars (with v sin i > 200 km s−1) is mostly populated by post-interaction binary products. In particular, we find that the final statistics of identified spectroscopic binaries and apparent single stars are in good agreement with newly computed predictions obtained with the binary population synthesis code BPASS and earlier estimations obtained in previous studies.

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“…In particular, Ferrario et al (2009); Schneider et al (2016) suggested that large-scale magnetism among massive stars originates in mergers. Because of the presence of a magnetic field in one component of Plaskett's star, close binary interactions were also thought to be possible generators, but this was discarded by observations (Nazé et al 2017).…”

Section: Incidence Of Magnetismmentioning

confidence: 99%

The IACOB project VIII. Searching for empirical signatures of binarity in fast-rotating O-type stars

Britavskiy¹,

S.²,

Holgado³

et al. 2023

Preprint

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Context. The empirical distribution of projected rotational velocities (v sin i) in massive O-type stars is characterized by a dominant slow velocity component and a tail of fast rotators. Binary interaction has been proposed to play a dominant role in the formation of this tail. Aims. We perform a complete and homogeneous search for empirical signatures of binarity in a sample of 54 fast rotating stars with the aim of evaluating this hypothesis. This working sample has been extracted from a larger sample of 415 Galactic O-type stars which covers the full range of v sin i values. Methods. We use new and archival multi-epoch spectra in order to detect spectroscopic binary systems. We complement this information with Gaia proper motions and TESS photometric data to aid in the identification of runaway stars and eclipsing binaries, respectively. We also benefit from additional published information to provide a more complete overview of the empirical properties of our working sample of fast-rotating O-type stars.Results. The identified fraction of single-lined spectroscopic binary (SB1) systems and apparently single stars among the fast-rotating sample is ∼18% and ∼70%, respectively. The remaining 12% correspond to four secure double-line spectroscopic binaries (SB2) with at least one of the components having a v sin i > 200 km s −1 (∼8%), and a small sample of 2 stars (∼4%) for which the SB2 classification is doubtful: they could actually be single stars with a remarkable line-profile variability. When comparing these percentages with those corresponding to the slow rotating sample we find that our sample of fast rotators is characterized by a slightly larger percentage of SB1 systems (∼18% vs. ∼13%) and a considerably smaller fraction of clearly detected SB2 systems (8% vs. 33%). Overall, there seems to be a clear deficit of spectroscopic binaries (SB1+SB2) among fast rotating O-type stars (∼26% vs. ∼46%). On the contrary, the fraction of runaway stars is significantly higher in the fast-rotating domain (∼33-50%) than among those stars with v sin i < 200 km s −1 . Lastly, almost 65% of the apparently single fast-rotating stars are runaways. As a by-product, we have discovered a new over contact SB2 system (HD 165921) and two fast-rotating SB1 systems (HD 46485 and HD 152200) Also, we propose HD 94024 and HD 12323 (both SB1 systems with a v sin i < 200 km s −1 ) as candidates to host a quiescent stellar-mass black hole. Conclusions. Our empirical results seem to be in good agreement with the idea that the tail of fast-rotating O-type stars (with v sin i > 200 km s −1 ) is mostly populated by post-interaction binary products. In particular, we find that the final statistics of identified spectroscopic binaries and apparently single stars are in good agreement with newly computed predictions obtained with the binary population synthesis code BPASS and previous estimations obtained by previous authors.

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How unique is Plaskett’s star? A search for organized magnetic fields in short period, interacting or post-interaction massive binary systems

Cited by 6 publications

References 57 publications

Diving into the magnetosphere of the Of?p star HD 108

Diving into the magnetosphere of the Of?p star HD 108

The IACOB project

The IACOB project VIII. Searching for empirical signatures of binarity in fast-rotating O-type stars

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