snapshot: connections between internal and surface properties of massive stars

Farrell, Eoin; Groh, J. H.; Meynet, Georges; Eldridge, J. J.; Ekström, Sylvia; Georgy, Cyril

doi:10.1093/mnras/staa1360

Cited by 20 publications

(11 citation statements)

References 148 publications

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“…After the main-sequence, they evolve to the red supergiant region, where they burn a significant fraction of helium in the core and, at the same time, lose a considerable amount of mass. When the helium core occupies about 70% of the total mass, the stars evolve bluewards, crossing the HRD for the second time (Giannone 1967;Farrell et al 2020). They thus have another BSG stage, where they consume the remaining helium in the core.…”

Section: Evolutionary Models With Schwarzschild Andmentioning

confidence: 99%

Blue supergiants as tests for stellar physics

Georgy

Saio

Meynet

2021

A&A

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Context. Massive star evolution is still poorly understood, and observational tests are required to discriminate between different implementations of physical phenomena in stellar evolution codes. Aims. By confronting stellar evolution models with observed properties of blue supergiants, such as pulsations, the chemical composition, and position in the Hertzsprung-Russell diagram, we aim to determine which of the criteria used for convection (Schwarzschild or Ledoux) is best able to explain the observations. Methods. We computed state-of-the-art stellar evolution models with either the Schwarzschild or the Ledoux criterion for convection. Models are for 14 to 35 M⊙ at solar or Large Magellanic Cloud metallicity. For each model, we computed the pulsation properties to know when radial modes are excited. We then compared our results with the position of blue supergiants in the Hertzsprung-Russell diagram, with their surface chemical composition and with their variability. Results. Our results at Large Magellanic Cloud metallicity shows only a slight preference for the Ledoux criterion over the Schwarzschild one in reproducing, at the same time, the observed properties of blue supergiants, even if the Schwarzschild criterion cannot be excluded at this metallicity. We checked that changing the overshoot parameter at solar metallicity does not improve the situation. We also checked that our models are able to reproduce the position of Galactic blue supergiants in the flux-weighted-gravity–luminosity relation. Conclusions. We confirm that overall, models computed with the Ledoux criterion are slightly better in matching observations. Our results also support the idea that most Galactic α Cyg variables are blue supergiants from group 2, that is stars that have been through a previous red supergiant phase where they have lost a large amount of mass.

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Section: Evolutionary Models With Schwarzschild Andmentioning

confidence: 99%

Blue supergiants as tests for stellar physics

Georgy

Saio

Meynet

2021

A&A

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“…Gräfener, Owocki & Vink 2012;Jiang et al 2018). Additionally, the radius is strongly impacted by uncertainties related to the chemical abundance profile in the envelope (Farrell et al 2020), which is impacted by the properties of mixing (e.g. Schootemeijer et al 2019).…”

Section: Smaller Radius Disfavours Binary Interactionmentioning

confidence: 99%

Is GW190521 the merger of black holes from the first stellar generations?

Farrell

Groh

Hirschi

et al. 2020

Monthly Notices of the Royal Astronomical Society: Letters

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GW190521 challenges our understanding of the late-stage evolution of massive stars and the effects of the pair instability in particular. We discuss the possibility that stars at low or zero metallicity could retain most of their hydrogen envelope until the pre-supernova stage, avoid the pulsational pair-instability regime, and produce a black hole with a mass in the mass gap by fallback. We present a series of new stellar evolution models at zero and low metallicity computed with the geneva and mesa stellar evolution codes and compare to existing grids of models. Models with a metallicity in the range 0–0.0004 have three properties that favour higher black hole (BH) masses. These are (i) lower mass-loss rates during the post main sequence phase, (ii) a more compact star disfavouring binary interaction, and (iii) possible H–He shell interactions which lower the CO core mass. We conclude that it is possible that GW190521 may be the merger of black holes produced directly by massive stars from the first stellar generations. Our models indicate BH masses up to 70–75 M⊙. Uncertainties related to convective mixing, mass loss, H–He shell interactions, and pair-instability pulsations may increase this limit to ∼85 M⊙.

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“…Gräfener et al 2012;Jiang et al 2018). Additionally, the radius is strongly impacted by uncertainties related to the chemical abundance profile in the envelope (Farrell et al 2020), which is impacted by the properties of mixing (e.g. Schootemeijer et al 2019;Higgins & Vink 2020).…”

Section: Smaller Radius Disfavours Binary Interactionmentioning

confidence: 99%

Is GW190521 the merger of black holes from the first stellar generations?

Farrell,

Groh,

Hirschi

et al. 2020

Preprint

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GW190521 challenges our understanding of the late-stage evolution of massive stars and the effects of the pair-instability in particular. We discuss the possibility that stars at low or zero metallicity could retain most of their hydrogen envelope until the pre-supernova stage, avoid the pulsational pair-instability regime and produce a black hole with a mass in the mass gap by fallback. We present a series of new stellar evolution models at zero and low metallicity computed with the Geneva and MESA stellar evolution codes and compare to existing grids of models. Models with a metallicity in the range 0 -0.0004 have three properties which favour higher BH masses as compared to higher metallicity models. These are (i) lower mass-loss rates during the post-MS phase, (ii) a more compact star disfavouring binary interaction and (iii) possible H-He shell interactions which lower the CO core mass. We conclude that it is possible that GW190521 may be the merger of black holes produced directly by massive stars from the first stellar generations. Our models indicate BH masses up to 70-75 M . Uncertainties related to convective mixing, mass loss, H-He shell interactions and pair-instability pulsations may increase this limit to ∼ 85M .

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snapshot: connections between internal and surface properties of massive stars

Cited by 20 publications

References 148 publications

Blue supergiants as tests for stellar physics

Blue supergiants as tests for stellar physics

Is GW190521 the merger of black holes from the first stellar generations?

Is GW190521 the merger of black holes from the first stellar generations?

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