The end of super AGB and massive AGB stars

Lau, Herbert H. B.; Gil‐Pons, Pilar; Doherty, Carolyn; Lattanzio, John C.

doi:10.1051/0004-6361/201218826

Cited by 63 publications

(80 citation statements)

References 39 publications

(51 reference statements)

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“…The proximity of the guest star to the Crab Nebula (M 1 or NGC 1952) was first pointed out by Lundmark (1921). The expansion of the Crab Nebula, which was discovered by Lampland (1921) and Duncan (1921), is consistent with the explosion occurring in 1054 (Hubble 1928;Rudie et al 2008, but see also Trimble 1968;Wyckoff & Murray 1977;Nugent 1998).…”

Section: Sn 1054 (Crab Nebula)mentioning

confidence: 80%

Electron-capture supernovae exploding within their progenitor wind

Moriya

Tominaga

Langer

et al. 2014

A&A

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The most massive stars on the asymptotic giant branch (AGB), or the so-called super-AGB stars, are thought to produce supernovae triggered by electron captures in their degenerate O+Ne+Mg cores. Super-AGB stars are expected to have slow winds with high mass-loss rates, so their circumstellar density is high. The explosions of super-AGB stars are therefore presumed to occur in this dense circumstellar environment. We provide the first synthetic light curves for such events by exploding realistic electron-capture supernova progenitors within their super-AGB winds. We find that the early light curve -that is, before the recombination wave reaches the bottom of the hydrogen-rich envelope of supernova ejecta (the plateau phase) -is not affected by the dense wind. However, after the luminosity drop following the plateau phase, the luminosity remains much higher when the super-AGB wind is taken into account. We compare our results to the historical light curve of SN 1054, the progenitor of the Crab Nebula, and show that the explosion of an electron-capture supernova within an ordinary super-AGB wind can explain the observed light curve features. We conclude that SN 1054 could have been a Type IIn supernova without any extra extreme mass loss, which was previously suggested to be necessary to account for its early high luminosity. We also show that our light curves match Type IIn supernovae with an early plateau phase or the so-called Type IIn-P supernovae, and suggest that they are electron-capture supernovae within super-AGB winds. Although some electron-capture supernovae can be bright in the optical spectral range due to the large progenitor radius, their X-ray luminosity from the interaction does not necessarily get as bright as other Type IIn supernovae whose optical luminosities are also powered by the interaction. Thus, we suggest that optically bright X-ray-faint Type IIn supernovae can emerge from electron-capture supernovae. Optically faint Type IIn supernovae, such as SN 2008S, can also originate from electron-capture supernovae if their hydrogen-rich envelope masses are small. We argue that some of them can be observed as Type IIn-b supernovae due to the small hydrogen-rich envelope mass.

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Section: Sn 1054 (Crab Nebula)mentioning

confidence: 80%

Electron-capture supernovae exploding within their progenitor wind

Moriya

Tominaga

Langer

et al. 2014

A&A

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“…All intermediate-mass stars experienced convergence problems of the type discussed by Lau et al (2012) and the models terminated with reasonably large envelope masses (≈ 1M ⊙ ). This means that the lifetimes given in Tables 1 and 2 are lower limits although in we estimated that one or two missed TPs is not going to affect the total stellar lifetimes or AGB lifetimes of models with M 2.4M ⊙ .…”

Section: The C/o Ratiomentioning

confidence: 92%

Helium enrichment and carbon-star production in metal-rich populations

Karakas

2014

Monthly Notices of the Royal Astronomical Society

141

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We present new theoretical stellar evolutionary models of metal-rich asymptotic giant branch (AGB) stars. Stellar models are evolved with initial masses between 1M ⊙ and 7M ⊙ at Z = 0.007, and 1M ⊙ and 8M ⊙ at Z = 0.014 (solar) and at Z = 0.03. We evolve models with a canonical helium abundance and with helium enriched compositions (Y = 0.30, 0.35, 0.40) at Z = 0.014 and Z = 0.03. The efficiency of third dredge-up and the mass range of carbon stars decreases with an increase in metallicity. We predict carbon stars form from initial masses between 1.75-7M ⊙ at Z = 0.007 and between 2-4.5M ⊙ at solar metallicity. At Z = 0.03 the mass range for C-star production is narrowed to 3.25-4M ⊙ . The third dredge-up is reduced when the helium content of the model increases owing to the reduced number of thermal pulses on the AGB. A small increase of ∆Y = 0.05 is enough to prevent the formation of C stars at Z = 0.03, depending on the mass-loss rate, whereas at Z = 0.014, an increase of ∆Y 0.1 is required to prevent the formation of C stars. We speculate that the probability of finding C stars in a stellar population depends as much on the helium abundance as on the metallicity. To explain the paucity of C stars in the inner region of M31 we conclude that the observed stars have Y 0.35 or that the stellar metallicity is higher than [Fe/H] ≈ 0.1.

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“…The values of M fin env in the case of the Z = 0.02 models are still relatively high due to convergence issues at the end of the calculations (Lau et al 2012). Due to the high mass-loss rate at this point of the evolution, only one or two more TPs are possible before the envelope is lost and it is uncertain if any more TDUs would occur following these TPs.…”

Section: The Stellar Structure Sequencesmentioning

confidence: 99%

Partial mixing and the formation of 13C pockets in AGB stars: effects on the s-process elements

Buntain

Doherty

Lugaro

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The production of the elements heavier than iron via slow neutron captures (the s process) is a main feature of the contribution of asymptotic giant branch (AGB) stars of low mass (< 5 Msun) to the chemistry of the cosmos. However, our understanding of the main neutron source, the 13 C(α,n) 16 O reaction, is still incomplete. It is commonly assumed that in AGB stars mixing beyond convective borders drives the formation of 13 C pockets. However, there is no agreement on the nature of such mixing and free parameters are present. By means of a parametric model we investigate the impact of different mixing functions on the final s-process abundances in low-mass AGB models. Typically, changing the shape of the mixing function or the mass extent of the region affected by the mixing produce the same results. Variations in the relative abundance distribution of the three s-process peaks (Sr, Ba, and Pb) are generally within +/-0.2 dex, similar to the observational error bars. We conclude that other stellar uncertainties -the effect of rotation and of overshoot into the C-O core -play a more important role than the details of the mixing function. The exception is at low metallicity, where the Pb abundance is significantly affected. In relation to the composition observed in stardust SiC grains from AGB stars, the models are relatively close to the data only when assuming the most extreme variation in the mixing profile.

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The end of super AGB and massive AGB stars

Cited by 63 publications

References 39 publications

Electron-capture supernovae exploding within their progenitor wind

Electron-capture supernovae exploding within their progenitor wind

Helium enrichment and carbon-star production in metal-rich populations

Partial mixing and the formation of 13C pockets in AGB stars: effects on the s-process elements

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