Rotation, spectral variability, magnetic geometry and magnetosphere of the Of?p star CPD −28° 2561★

Wade, G. A.; Barbá, R. H.; Grunhut, J.; Martins, F.; Petit, Véronique; Sundqvist, J. O.; Townsend, R. H. D.; Walborn, N. R.; Alécian, E.; Alfaro, E. J.; Apellániz, J. Maíz; Arias, J. I.; Gamen, R.; Morrell, N.; Nazé, Yaël; Sota, A.; ud‐Doula, Asif

doi:10.1093/mnras/stu2548

Cited by 35 publications

(58 citation statements)

References 46 publications

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“…Continuing the work of Wade et al (2015), we present in this paper high-energy monitoring of CPD −28…”

Section: Introductionmentioning

confidence: 85%

“…Subsequent spectroscopic and spectropolarimetric monitoring (Wade et al 2015) further established the star's properties: its (rotation) period is 73.41d, its surface dipolar field B d amounts to ∼2.5 kG, and its wind magnetic confinement parameter η * is about 100, implying strong confinement. Notably, during one magnetic cycle, the Balmer and He i lines present a double-wave variation, i.e.…”

Section: Introductionmentioning

confidence: 97%

“…With such a configuration, MHD modelling is able to reproduce the variations of the equivalent width of the Hα line (Wade et al 2015).…”

Section: Introductionmentioning

confidence: 99%

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The changing UV and X-ray properties of the Of?p star CPD −28°2561

Nazé¹,

Sundqvist²,

Fullerton³

et al. 2015

Mon. Not. R. Astron. Soc.

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The Of?p star CPD −28• 2561 was monitored at high energies with XMM-Newton and HST. In X-rays, this magnetic oblique rotator displays bright and hard emission that varies by ∼55% with rotational phase. These changes occur in phase with optical variations, as expected for magnetically confined winds; there are two maxima and two minima in X-rays during the 73d rotational period of CPD −28• 2561. However, contrary to previously studied cases, no significant hardness variation is detected between minima and maxima, with the exception of the second minimum which is slightly distinct from the first one. In the UV domain, broad-band fluxes remain stable while line profiles display large variations. Stronger absorptions at low velocities are observed when the magnetic equator is seen edge-on, which can be reproduced by a detailed 3D model. However, a difference in absorption at high velocities in the C iv and N v lines is also detected for the two phases where the confined wind is seen nearly pole-on. This suggests the presence of strong asymmetries about the magnetic equator, mostly in the free-flowing wind (rather than in the confined dynamical magnetosphere).

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“…Continuing the work of Wade et al (2015), we present in this paper high-energy monitoring of CPD −28…”

Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 97%

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The changing UV and X-ray properties of the Of?p star CPD −28°2561

Nazé¹,

Sundqvist²,

Fullerton³

et al. 2015

Mon. Not. R. Astron. Soc.

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“…We have included seven known magnetic O stars in our abundance study: θ 1 Ori C (Donati et al 2002;Wade et al 2006), HD 57682 (Grunhut et al 2009), HD 108 (Martins et al 2010), HD 148937 (Hubrig et al 2008;Wade et al 2012), HD 191612 (Donati et al 2006Wade et al 2011), Tr16-22 (Nazé et al 2012, and CPD-28 2561 (Wade et al 2015;Hubrig et al 2014). Figures 4 and 5 indicate that these magnetic stars have surface abundances that do not depart from other O-type stars.…”

Section: Magnetic Starsmentioning

confidence: 99%

The MiMeS survey of magnetism in massive stars: CNO surface abundances of Galactic O stars

Martins¹,

Hervé²,

Bouret³

et al. 2015

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Context. The evolution of massive stars is still partly unconstrained. Mass, metallicity, mass loss, and rotation are the main drivers of stellar evolution. Binarity and the magnetic field may also significantly affect the fate of massive stars. Aims. Our goal is to investigate the evolution of single O stars in the Galaxy. Methods. For that, we used a sample of 74 objects comprising all luminosity classes and spectral types from O4 to O9.7. We relied on optical spectroscopy obtained in the context of the MiMeS survey of massive stars. We performed spectral modelling with the code CMFGEN. We determined the surface properties of the sample stars, with special emphasis on abundances of carbon, nitrogen, and oxygen. Results. Most of our sample stars have initial masses in the range of 20 to 50 M . We show that nitrogen is more enriched and carbon and oxygen are more depleted in supergiants than in dwarfs, with giants showing intermediate degrees of mixing. CNO abundances are observed in the range of values predicted by nucleosynthesis through the CNO cycle. More massive stars, within a given luminosity class, appear to be more chemically enriched than lower mass stars. We compare our results with predictions of three types of evolutionary models and show that for two sets of models, 80% of our sample can be explained by stellar evolution including rotation. The effect of magnetism on surface abundances is unconstrained. Conclusions. Our study indicates that in the 20−50 M mass range, the surface chemical abundances of most single O stars in the Galaxy are fairly well accounted for by stellar evolution of rotating stars.

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“…If binary interactions, in particular mass transfer events, constitute a dominant process for the generation of magnetic fields of massive stars, then most (if not all) of these systems would possess a magnetic component. In that case, we would thus have identified a specific group of magnetic O-stars, the second such category after the group of Of?p stars which were all found to be magnetic since the pioneering detection of 2006 (HD 191612, Donati et al 2006;Wade et al 2011;HD 148937, Hubrig et al 2008;Wade et al 2012a;HD 108, Martins et al 2010;NGC1624-2, Wade et al 2012bCPD −28 • 2561, Hubrig et al 2012Wade et al 2015). On the contrary, if mass transfer events are not a source of strong, large-scale magnetic fields, then the magnetic incidence in these systems would not differ significantly from that found for large stellar samples (Fossati et al 2015b;Grunhut et al 2016).…”

mentioning

confidence: 92%

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

Nazé

Neiner

Grunhut

et al. 2017

Mon. Not. R. Astron. Soc.

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Amongst O-type stars with detected magnetic fields, the fast rotator in the close binary called Plaskett's star shows a variety of unusual properties. Since strong binary interactions are believed to have occurred in this system, one may wonder about their potential role in generating magnetic fields. Stokes V spectra collected with the low-resolution FORS2 and high-resolution ESPaDOnS and Narval spectropolarimeters were therefore used to search for magnetic fields in 15 interacting or post-interaction massive binaries. No magnetic field was detected in any of them, with 0 G always being within 2σ of the derived values. For 17 out of 25 stars in the systems observed at high-resolution, the 90% upper limit on the individual dipolar fields is below the dipolar field strength of Plaskett's secondary; a similar result is found for five out of six systems observed at low resolution. If our sample is considered to form a group of stars sharing similar magnetic properties, a global statistical analysis results in a stringent upper limit of ∼ 200 G on the dipolar field strength. Moreover, the magnetic incidence rate in the full sample of interacting or post-interaction systems (our targets + Plaskett's star) is compatible with that measured from large surveys, showing that they are not significantly different from the general O-star population. These results suggest that binary interactions play no systematic role in the magnetism of such massive systems.

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Rotation, spectral variability, magnetic geometry and magnetosphere of the Of?p star CPD −28° 2561★

Cited by 35 publications

References 46 publications

The changing UV and X-ray properties of the Of?p star CPD −28°2561

The changing UV and X-ray properties of the Of?p star CPD −28°2561

The MiMeS survey of magnetism in massive stars: CNO surface abundances of Galactic O stars

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

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