The spin rates of O stars in WR + O binaries – I. Motivation, methodology, and first results from SALT

Shara, Michael M.; Crawford, S.; Vanbeveren, D.; Moffat, A. F. J.; Zurek, David; Crause, Lisa A.

doi:10.1093/mnras/stw2450

Cited by 25 publications

(21 citation statements)

References 45 publications

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“…This exercise then yields a set of most probable WR+O star binary properties that are given in Table 2. As was already concluded by Shara et al (2017) the 11 WR+O binaries in our sample have O-type components that seem to be spun up, i.e. the 11 WR+O binaries all show the signature of mass transfer 5 .…”

Section: The Wr+o Binaries: the Spin-rates Of The O Componentssupporting

confidence: 80%

“…The inclination angle-range i = 40-62 • . The mass-spectral type relation predicts a (generous) 24-34 M ⊙ mass range for an O8V star; this means that an i-value close to 40 • is to be preferred and therefore an equatorial velocity close to the maximum value given in Shara et al (2017) should be retained, i.e. 336/274 km/s.…”

Section: The Wr+o Binaries: the Spin-rates Of The O Componentsmentioning

confidence: 97%

“…Column 7 lists the rotation velocities at the end of the RLOF (= the beginning of the WR phase) of the progenitor binary calculated as explained in the text. The v rot column 6 lists the speed values resulting from the He I/He II line measurements as explained inShara et al (2017). A question mark means that this particular measurement is not available.…”

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confidence: 99%

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Spin rates and spin evolution of O components in WR+O binaries

Vanbeveren

Mennekens

Shara

et al. 2018

A&A

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Context. Despite 50 years of extensive binary research we have to conclude that the Roche lobe overflow/mass transfer process that governs close binary evolution is still poorly understood. Aims. It is the scope of the present paper to lift a tip of the veil by studying the spin-up and spin-down processes of the O-type components of WR+O binaries. Methods. We critically analyze the available observational data of rotation speeds of the O-type components in WR+O binaries. By combining a binary evolutionary code and a formalism that describes the effects of tides in massive stars with an envelope in radiative equilibrium, we compute the corresponding rotational velocities during the Roche lobe overflow of the progenitor binaries. Results. In all the studied WR+O binaries, we find that the O-type stars were affected by accretion of matter during the RLOF of the progenitor. This means that common envelope evolution which excludes any accretion onto the secondary O-star, has not played an important role to explain the WR+O binaries. Moreover, although it is very likely that the O-type star progenitors were spun-up by the mass transfer, many ended the RLOF/mass transfer phase with a rotational velocity that is significantly smaller than the critical rotation speed. This may indicate that during the mass transfer phase there is a spin-down process which is of the same order as, although significantly less than that of the spin-up process. We propose a Spruit-Tayler type dynamo spin-down suggested in the past to explain the rotation speeds of the mass gainers in long-period Algols.

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Section: The Wr+o Binaries: the Spin-rates Of The O Componentssupporting

confidence: 80%

Section: The Wr+o Binaries: the Spin-rates Of The O Componentsmentioning

confidence: 97%

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Spin rates and spin evolution of O components in WR+O binaries

Vanbeveren

Mennekens

Shara

et al. 2018

A&A

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“…Two competing scenarios exist for the removal of (most of) the hydrogen-rich envelope of stars: the single star picture (so-called Conti scenario, Conti 1975;Maeder & Conti 1994;Lamers 2013) and the binary formation channel (e.g., Woosley et al 1995;Wellstein & Langer 1999;Smith & Tombleson 2015;Shara et al 2017). Understanding mass loss phenomena is necessary to discriminate between these two scenarios.…”

Section: Introductionmentioning

confidence: 99%

Systematic survey of the effects of wind mass loss algorithms on the evolution of single massive stars

Renzo¹,

Ott²,

Shore³

et al. 2017

A&A

131

150

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Mass loss processes are a key uncertainty in the evolution of massive stars. They determine the amount of mass and angular momentum retained by the star, thus influencing its evolution and presupernova structure. Because of the high complexity of the physical processes driving mass loss, stellar evolution calculations must employ parametric algorithms, and usually only include wind mass loss. We carried out an extensive parameter study of wind mass loss and its effects on massive star evolution using the open-source stellar evolution code MESA. We provide a systematic comparison of wind mass loss algorithms for solar-metallicity, nonrotating, single stars in the initial mass range of 15 M to 35 M . We consider combinations drawn from two hot phase (i.e., roughly the main sequence) algorithms, three cool phase (i.e., post-main-sequence) algorithms, and two Wolf-Rayet mass loss algorithms. We discuss separately the effects of mass loss in each of these phases. In addition, we consider linear wind efficiency scale factors of 1, 0.33, and 0.1 to account for suggested reductions in mass loss rates due to wind inhomogeneities. We find that the initial to final mass mapping for each zero-age main-sequence (ZAMS) mass has a ∼50% uncertainty if all algorithm combinations and wind efficiencies are considered. The ad-hoc efficiency scale factor dominates this uncertainty. While the final total mass and internal structure of our models vary tremendously with mass loss treatment, final luminosity and effective temperature are much less sensitive for stars with ZAMS mass 30 M . This indicates that uncertainty in wind mass loss does not negatively affect estimates of the ZAMS mass of most single-star supernova progenitors from pre-explosion observations. Our results furthermore show that the internal structure of presupernova stars is sensitive to variations in both main sequence and post main-sequence mass loss. The compactness parameter ξ ∝ M/R(M) has been identified as a proxy for the "explodability" of a given presupernova model. We find that ξ varies by as much as 30% for models of the same ZAMS mass evolved with different wind efficiencies and mass loss algorithm combinations. This suggests that the details of the mass loss treatment might bias the outcome of detailed core-collapse supernova calculations and the predictions for neutron star and black hole formation.

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“…4, 5 that depending on parameters and the cluster age, the 22 Ne/ 20 Ne ratio can be both well above and below the observed value. Spin rates of the massive O-and WR stars in the Galaxy are found to be ∼ 100 km s −1 for single stars and ∼ 200 − 400 km s −1 for binaries (Penny 1996, Howarth et al 1997, Shara et al 2017. This results in higher amount of 22 Ne generating in a cluster according to model predictions.…”

Section: Modeling Of 22mentioning

confidence: 91%

High-Energy Particles and Radiation in Star-Forming Regions

et al. 2020

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Non-thermal particles and high-energy radiation can play a role in the dynamical processes in star-forming regions and provide an important piece of the multiwavelength observational picture of their structure and components. Powerful stellar winds and supernovae in compact clusters of massive stars and OB associations are known to be favourable sites of high-energy particle acceleration and sources of non-thermal radiation and neutrinos. Namely, young massive stellar clusters are likely sources of the PeV (petaelectronvolt) regime cosmic rays (CRs). They can also be responsible for the cosmic ray composition, e.g., 22 Ne/ 20 Ne anomalous isotopic ratio in CRs. Efficient particle acceleration can be accompanied by super-adiabatic amplification of the fluctuating magnetic fields in the systems converting a part of kinetic power of the winds and supernovae into the magnetic energy through the CR-driven instabilities. The escape and CR propagation in the vicinity of the sources are affected by the non-linear CR feedback. These effects are expected to be important in starburst galaxies, which produce high-energy neutrinos and gamma-rays. We give a brief review of the theoreti-A. M. Bykov

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The spin rates of O stars in WR + O binaries – I. Motivation, methodology, and first results from SALT

Cited by 25 publications

References 45 publications

Spin rates and spin evolution of O components in WR+O binaries

Spin rates and spin evolution of O components in WR+O binaries

Systematic survey of the effects of wind mass loss algorithms on the evolution of single massive stars

High-Energy Particles and Radiation in Star-Forming Regions

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