Detection of magnetic fields in both B-type components of the ϵ Lupi system: a new constraint on the origin of fossil fields?

Shultz, Matt; Wade, G. A.; Alécian, E.; Collaboration, BinaMIcS

doi:10.1093/mnrasl/slv096

Cited by 41 publications

(39 citation statements)

References 40 publications

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“…The three binary stars showing Hα-emission are all very young, and their CMs are no larger than single Hα-bright stars of comparable ages (Shultz et al 2019c). The two close binary systems without Hα emission, HD 136504 (in which system both components are magnetic, Shultz et al 2015) and HD 149277, are middle-aged and have CMs that are somewhat smaller than the average of their contemporaries.…”

Section: Evolution Of Rotation and Confinementmentioning

confidence: 99%

The effects of surface fossil magnetic fields on massive star evolution – II. Implementation of magnetic braking in mesa and implications for the evolution of surface rotation in OB stars

Keszthelyi

Meynet

Shultz

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The time evolution of angular momentum and surface rotation of massive stars is strongly influenced by fossil magnetic fields via magnetic braking. We present a new module containing a simple, comprehensive implementation of such a field at the surface of a massive star within the Modules for Experiments in Stellar Astrophysics (mesa) software instrument. We test two limiting scenarios for magnetic braking: distributing the angular momentum loss throughout the star in the first case, and restricting the angular momentum loss to a surface reservoir in the second case. We perform a systematic investigation of the rotational evolution using a grid of OB star models with surface magnetic fields (M = 5 − 60 M , Ω/Ω crit = 0.2 − 1.0, B p = 1 − 20 kG). We then employ a representative grid of B-type star models (M = 5, 10, 15 M , Ω/Ω crit = 0.2, 0.5, 0.8, B p = 1, 3, 10, 30 kG) to compare to the results of a recent selfconsistent analysis of the sample of known magnetic B-type stars. We infer that magnetic massive stars arrive at the zero age main sequence with a range of rotation rates, rather than with one common value. In particular, some stars are required to have close-to-critical rotation at the ZAMS. However, magnetic braking yields surface rotation rates converging to a common low value, making it difficult to infer the initial rotation rates of evolved, slowly-rotating stars.

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Section: Evolution Of Rotation and Confinementmentioning

confidence: 99%

The effects of surface fossil magnetic fields on massive star evolution – II. Implementation of magnetic braking in mesa and implications for the evolution of surface rotation in OB stars

Keszthelyi

Meynet

Shultz

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Carrier et al (2002) in Ap stars and now confirmed by the BinaMIcS project in more massive OB stars: the magnetic incidence in close, massive binaries is no more than about 2% (Neiner & Alecian 2013;Alecian et al 2015;Neiner et al 2015). As of today there is only one binary with a magnetic field detection in both components, the eccentric (e = 0.27), 4.56 d B-star binary Lupi (Shultz et al 2015b).…”

Section: Introductionmentioning

confidence: 99%

Rejuvenation of stellar mergers and the origin of magnetic fields in massive stars

Schneider

Podsiadlowski

Langer

et al. 2016

Mon. Not. R. Astron. Soc.

123

114

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Approximately 10% of massive OBA main-sequence (MS) and pre-MS stars harbour strong, large-scale magnetic fields. At the same time there is a dearth of magnetic stars in close binaries. A process generating strong magnetic fields only in some stars must be responsible with the merging of pre-MS and MS stars being suggested as one such channel. Stars emerging from the coalescence of two MS stars are rejuvenated, appearing younger than they are. They can therefore be identified by comparison with reference clocks. Here we predict the rejuvenation of MS merger products over a wide range of masses and binary configurations calibrated to smoothed-particlehydrodynamical merger models. We find that the rejuvenation is of the order of the nuclear timescale and is strongest in the lowest-mass mergers and the most evolved binary progenitors with the largest mass ratios. These predictions allow us to put constraints on the binary progenitors of merger products. We show that the magnetic stars HR 2949 and τ Sco are younger than the potential binary companion HR 2948 and the Upper-Sco association, respectively, making them promising merger candidates. We find that the age discrepancies and the potential binary progenitors of both are consistent with them being rejuvenated merger products, implying that their magnetic fields may originate from this channel. Searching for age discrepancies in magnetic stars is therefore a powerful way to explore which fraction of magnetic stars may have obtained their strong magnetic field in MS mergers and to improve our understanding of magnetism in massive stars and their remnants.

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“…Landstreet & Mathys 2000), we can wonder whether the small β value is another consequence of tidal interactions. Interestingly, two other close binary systems containing magnetic Ap/Bp stars, Lup (Shultz et al 2015) and HD 5550 (Alecian et al 2016), also share the characteristic of magnetic fields having small values of β.…”

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confidence: 99%

BD-19 5044L: discovery of a short-period SB2 system with a magnetic Bp primary in the open cluster IC 4725

Landstreet¹,

Kochukhov²,

Alécian³

et al. 2017

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Context. Until recently almost nothing was known about the evolution of magnetic fields found in upper main sequence Ap/Bp stars during their long main sequence lifetime. We are thus studying magnetic Ap/Bp stars in open clusters in order to obtain observational evidence of how the properties of Ap/Bp magnetic stars, such as field strength and structure, evolve with age during the main sequence. One important aspect of this study is to search for the very rare examples of hot magnetic stars in short-period binary systems among magnetic cluster members. Aims. In this paper we characterize the object BD-19 5044L, which is both a member of the open cluster IC 4725 = M 25, and a short-period SB2 system containing a magnetic primary star. Methods. We have obtained a series of intensity and circular polarisation spectra distributed through the orbital and rotation cycles of BD-19 5044L with the ESPaDOnS spectropolarimeter at CFHT. From these data we determine the orbital and stellar properties of each component. Results. We find that the orbit of BD-19 5044L AB is quite eccentric (e = 0.477), with a period of 17.63 d. The primary is a magnetic Bp star with a variable longitudinal magnetic field, a polar field strength of ∼ 1400 G and a low obliquity, while the secondary is probably a hot Am star and does not appear to be magnetic. The rotation period of the primary (5.04 d) is not synchronised with the orbit, but the rotation angular velocity is close to being synchronised with the orbital angular velocity of the secondary at periastron, perhaps as a result of tidal interactions. Because this system is a member of IC 4725, the two stars have a common age of log t = 8.02 ± 0.05 dex. Conclusions. The periastron separation is small enough (about 12 times the radius of the primary star) that BD-19 5044L may be one of the very rare known cases of a tidally interacting SB2 binary system containing a magnetic Ap/Bp star.

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Detection of magnetic fields in both B-type components of the ϵ Lupi system: a new constraint on the origin of fossil fields?

Cited by 41 publications

References 40 publications

The effects of surface fossil magnetic fields on massive star evolution – II. Implementation of magnetic braking in mesa and implications for the evolution of surface rotation in OB stars

The effects of surface fossil magnetic fields on massive star evolution – II. Implementation of magnetic braking in mesa and implications for the evolution of surface rotation in OB stars

Rejuvenation of stellar mergers and the origin of magnetic fields in massive stars

BD-19 5044L: discovery of a short-period SB2 system with a magnetic Bp primary in the open cluster IC 4725

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