Stellar mergers as the origin of magnetic massive stars

Schneider, F. R. N.; Ohlmann, Sebastian T.; Podsiadlowski, Philipp; Röpke, F. K.; Balbus, Steven A.; Pakmor, Rüdiger; Springel, Volker

doi:10.1038/s41586-019-1621-5

Cited by 233 publications

(225 citation statements)

References 45 publications

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“…It could also be that at least some magnetic stars follow an unusual trend on the HRD. In particular, HD 149438 (τ Sco) may be a blue straggler and is a promising candidate for a merger product (Schneider et al 2016(Schneider et al , 2019. Furthermore, τ Sco is also a significant example of a magnetic star that may present an apparently younger age than the age of the cluster that it belongs to (Nieva & Przybilla 2014;Schneider et al 2016).…”

Section: Evolution Of Rotation and Confinementmentioning

confidence: 99%

“…Surface magnetic braking has been implemented 2 in the Geneva stellar evolution code (Eggenberger et al 2008) and in the rose code (Potter et al 2012a) in the context of single magnetic OB stars (Meynet et al 2011;Georgy et al 2017;Potter et al 2012b), and supermassive stars (Haemmerlé & Meynet 2019). Furthermore, the Modules for Experiments in Stellar Astrophysics (mesa) software instrument (Paxton et al 2011(Paxton et al , 2013(Paxton et al , 2015(Paxton et al , 2018(Paxton et al , 2019 was used to test cases of massive star magnetic braking 3 , and also applied to model the magnetic star τ Sco (Schneider et al 2019). Additionally, magnetic braking has also been explored in other contexts, such as binary systems with surface magnetic braking (e.g., Rappaport et al 1983;Chen & Podsiadlowski 2016;Song et al 2018), and core magnetic braking (Maeder & Meynet 2014;Cantiello et al 2016;Kissin & Thompson 2018;Fuller et al 2019).…”

Section: Introductionmentioning

confidence: 99%

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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%

Section: Introductionmentioning

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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“…In those models, an unstable mass transfer phase leads to a stellar merger which unbinds part of the envelope. It is not clear what fraction of the envelope can be lost in the merging process, but hydrodynamical simulations suggest it is merely < 10% (Lombardi et al 1995;Schneider et al 2019). The rest of the envelope needs to be stripped through stellar winds, which is unlikely for low-metallicity stars.…”

Section: A Type Iib Supernova With Sub-solar Metallicity?mentioning

confidence: 99%

A Subsolar Metallicity Progenitor for Cassiopeia A, the Remnant of a Type IIb Supernova

Sato

Yoshida

Umeda

et al. 2020

ApJ

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We report, for the first time, the detection of the Mn-Kα line in the Type IIb supernova (SN IIb) remnant, Cassiopeia A. Manganese ( 55 Mn after decay of 55 Co), a neutron-rich element, together with chromium ( 52 Cr after decay of 52 Fe), is mainly synthesized in core-collapse supernovae at the explosive incomplete Si burning regime. Therefore, the Mn/Cr mass ratio with its neutron excess reflects the neutronization at the relevant burning layer during the explosion. Chandra's deep archival X-ray data of Cassiopeia A indicate a low Mn/Cr mass ratio with values in the range 0.10-0.66, which, when compared to one-dimensional SN explosion models, requires that the electron fraction be 0.4990 Y e 0.5 at the incomplete Si burning layer. An explosion model assuming a solarmetallicity progenitor with a typical explosion energy (1 × 10 51 erg) fails to reproduce such a high electron fraction. In such models, the explosive Si-burning regime extends only to the Si/O layer established during the progenitor's hydrostatic evolution; the Y e in the Si/O layer is lower than the value required by our observational constraints. We can satisfy the observed Mn/Cr mass ratio if the explosive Si-burning regime were to extend into the O/Ne hydrostatic layer, which has a higher Y e . This would require an energetic (> 2×10 51 erg) and/or asymmetric explosion of a sub-solar metallicity progenitor (Z 0.5Z ) for Cassiopeia A. The low initial metallicity can be used to rule out a singlestar progenitor, leaving the possibility of a binary progenitor with a compact companion (white dwarf, neutron star or black hole). We discuss the detectability of X-rays from Bondi accretion onto such a compact companion around the explosion site. We also discuss other possible mass-loss scenarios for the progenitor system of Cassiopeia A.

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“…vms stars are the result of either a stellar merger event or a binary mass-transfer event (e.g. Tutukov & Fedorova 2010;Schneider et al 2019). The merger hypothesis (e.g.…”

Section: Fnrs Senior Research Associatementioning

confidence: 99%

A search for strong magnetic fields in massive and very massive stars in the Magellanic Clouds

Bagnulo

Wade

Nazé

et al. 2020

A&A

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Despite their rarity, massive stars dominate the ecology of galaxies via their strong, radiatively-driven winds throughout their lives and as supernovae in their deaths. However, their evolution and subsequent impact on their environment can be significantly affected by the presence of a magnetic field. While recent studies indicate that about 7 % of OB stars in the Milky Way host strong, stable, organised (fossil) magnetic fields at their surfaces, little is known about the fields of very massive stars, nor the magnetic properties of stars outside our Galaxy. We aim to continue searching for strong magnetic fields in a diverse set of massive and very massive stars (VMS) in the Large and Small Magellanic Clouds (LMC/SMC), and we evaluate the overall capability of FORS2 to usefully search for and detect stellar magnetic fields in extra-galactic environments. We have obtained FORS2 spectropolarimetry of a sample of 41 stars, which principally consist of spectral types B, O, Of/WN, WNh, and classical WR stars in the LMC and SMC. Four of our targets are Of?p stars; one of them was just recently discovered. Each spectrum was analysed to infer the longitudinal magnetic field. No magnetic fields were formally detected in our study, although Bayesian statistical considerations suggest that the Of?p star SMC 159-2 is magnetic with a dipolar field of the order of 2.4 to 4.4 kG. In addition, our first constraints of magnetic fields in VMS provide interesting insights into the formation of the most massive stars in the Universe.

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Stellar mergers as the origin of magnetic massive stars

Cited by 233 publications

References 45 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

A Subsolar Metallicity Progenitor for Cassiopeia A, the Remnant of a Type IIb Supernova

A search for strong magnetic fields in massive and very massive stars in the Magellanic Clouds

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