Mass Loss: Its Effect on the Evolution and Fate of High-Mass Stars

Smith, Nathan

doi:10.1146/annurev-astro-081913-040025

Cited by 898 publications

(498 citation statements)

References 263 publications

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“…Similar and additional arguments (Smith et al 2010(Smith et al , 2011Smith 2014) favoring an explosive scenario have also been given for the broader population of giant-eruption LBVs.…”

Section: Concluding Discussionsupporting

confidence: 58%

The spectral temperature of optically thick outflows with application to light echo spectra from η Carinae's giant eruption

Owocki¹,

Shaviv²

2016

Mon. Not. R. Astron. Soc.

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The detection by Rest et al. (2012) of light echoes from η Carinae has provided important new observational constraints on the nature of its 1840's era giant eruption. Spectra of the echoes suggest a relatively cool spectral temperature of about 5500K, lower than the lower limit of about 7000K suggested in the optically thick wind outflow analysis of Davidson (1987). This has lead to a debate about the viability of this steady wind model relative to alternative, explosive scenarios. Here we present an updated analysis of the wind outflow model using newer low-temperature opacity tabulations and accounting for the stronger mass loss implied by the >10 Msun mass now inferred for the Homunculus. A major conclusion is that, because of the sharp drop in opacity due to free electron recombination for T <6500K, a low temperature of about 5000K is compatible with, and indeed expected from, a wind with the extreme mass loss inferred for the eruption. Within a spherical gray model in radiative equilibrium, we derive spectral energy distributions for various assumptions for the opacity variation of the wind, providing a basis for comparisons with observed light echo spectra. The scaling results here are also potentially relevant for other highly optically thick outflows, including those from classical novae, giant eruptions of LBVs and SN Type IIn precursors. A broader issue therefore remains whether the complex, variable features observed from such eruptions are better understood in terms of a steady or explosive paradigm, or perhaps a balance of these idealizations.

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“…Similar and additional arguments (Smith et al 2010(Smith et al , 2011Smith 2014) favoring an explosive scenario have also been given for the broader population of giant-eruption LBVs.…”

Section: Concluding Discussionsupporting

confidence: 58%

The spectral temperature of optically thick outflows with application to light echo spectra from η Carinae's giant eruption

Owocki¹,

Shaviv²

2016

Mon. Not. R. Astron. Soc.

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“…Weaver et al 1977;Chevalier 1982b;Dwarkadas 2005;Chevalier & Irwin 2011). However, recently evidence has been mounting that many massive stars experience highly variable stellar winds and eruptive mass-loss in the period before the explosion (see Smith 2014, for a review). The stellar winds are driven from the surface of the star, whereas the processes leading up to the core collapse occur deep in the interior, so it is unclear what drives mass-loss events shortly before the SN explosions.…”

Section: Introductionmentioning

confidence: 99%

SN 2014C: VLBI images of a supernova interacting with a circumstellar shell

Bietenholz

Kamble

Margutti³

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We report on VLBI measurements of supernova 2014C at several epochs between t = 384 and 1057 days after the explosion. SN 2014C was an unusual supernova that initially had Type Ib optical spectrum, but after t = 130 d it developed a Type IIn spectrum with prominent Hα lines, suggesting the onset of strong circumstellar interaction. Our first VLBI observation was at t = 384 d, and we find that the outer radius of SN 2014C was (6.40 ± 0.26) × 10 16 cm (for a distance of 15.1 Mpc), implying an average expansion velocity of 19300 ± 790 km s −1 up to that time. At our last epoch, SN 2014C was moderately resolved and shows an approximately circular outline but with an enhancement of the brightness on the W side. The outer radius of the radio emission at t = 1057 d is (14.9 ± 0.6) × 10 16 cm. We find that the expansion between t = 384 and 1057 d is well described by a constant velocity expansion with v = 13600 ± 650 km s −1 . SN 2014C had clearly been substantially decelerated by t = 384 d. Our measurements are compatible with a scenario where the expanding shock impacted upon a shell of dense circumstellar material during the first year, as suggested by the observations at other wavelengths, but had progressed through the dense shell by the time of the VLBI observations.

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“…Eruptive mass loss exhibited by luminous blue variables (LBVs) is thought to be important for the evolution of massive stars (Humphreys & Davidson 1994;Smith & Owocki 2006;Smith 2014), but the exact role LBVs play and the physics of their instability has been challenging to understand. The class of LBVs defined in the Milky Way and Magellanic Clouds (LMC/SMC) is thought to be responsible for some extragalactic non-supernova (SN) transients (Smith et al 2011;Van Dyk & Matheson 2012).…”

Section: Introductionmentioning

confidence: 99%

The Canonical Luminous Blue Variable AG Car and Its Neighbor Hen 3-519 Are Much Closer than Previously Assumed

Smith

Stassun

2017

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The strong mass loss of Luminous Blue Variables (LBVs) is thought to play a critical role in massive-star evolution, but their place in the evolutionary sequence remains debated. A key to understanding their peculiar instability is their high observed luminosities, which often depends on uncertain distances. Here we report direct distances and space motions of four canonical Milky Way LBVs-AGCar, HRCar, HD168607, and (candidate) Hen3-519-from the Gaia first data release. Whereas the distances of HRCar and HD168607 are consistent with previous literature estimates within the considerable uncertainties, Hen3-519 and AGCar, both at ∼2 kpc, are much closer than the 6-8 kpc distances previously assumed. As a result, Hen3-519 moves far from the locus of LBVs on the Hertzsprung-Russell diagram, making it a much less luminous object. For AGCar, considered a defining example of a classical LBV, its lower luminosity would also move it off the SDor instability strip. Lower luminosities allow both AGCar and Hen3-519 to have passed through a previous red supergiant phase, lower the mass estimates for their shell nebulae, and imply that binary evolution is needed to account for their peculiarities. These results may also impact our understanding of LBVs as potential supernova progenitors and their isolated environments. Improved distances will be provided in the Gaia second data release, which will include additional LBVs. AGCar and Hen3-519 hint that this new information may alter our traditional view of LBVs.

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Mass Loss: Its Effect on the Evolution and Fate of High-Mass Stars

Cited by 898 publications

References 263 publications

The spectral temperature of optically thick outflows with application to light echo spectra from η Carinae's giant eruption

The spectral temperature of optically thick outflows with application to light echo spectra from η Carinae's giant eruption

SN 2014C: VLBI images of a supernova interacting with a circumstellar shell

The Canonical Luminous Blue Variable AG Car and Its Neighbor Hen 3-519 Are Much Closer than Previously Assumed

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