We explore the final fates of massive intermediate-mass stars by computing detailed stellar models from zero-age main sequence until near end thermally pulsing phase. These super-asymptotic giant branch (super-AGB) and AGB star are in mass range between 5.0 10.0 M⊙ for metallicities spanning Z = 0.02–0.0001. probe limits Mup, Mn Mmass, minimum masses onset carbon burning, formation a neutron iron core-collapse supernovae, respectively, to constrain white dwarf/electron-capture supernova...

We have computed detailed evolution and nucleosynthesis models for super massive AGB stars over the mass range 6.5-9.0 Msun in divisions of 0.5 with metallicities Z=0.02, 0.008 0.004. These calculations, which we find third dredge-up hot bottom burning, fill gap between existing low intermediate-mass star high that become supernovae. For considered metallicities, composition yields is largely dominated by thermodynamic conditions at base convective envelope rather than pollution arising from...

We review the lives, deaths and nucleosynthetic signatures of intermediate mass stars in range approximately 6.5-12 Msun, which form super-AGB near end their lives. examine critical boundaries both between different types massive white dwarfs (CO, CO-Ne, ONe) supernovae discuss relative fraction that life as either an ONe dwarf or a neutron star (or ONeFe dwarf), after undergoing electron capture supernova. also contribution other potential single-star channels to electron-capture...

We present a new grid of stellar models and nucleosynthetic yields for super-AGB stars with metallicities Z = 0.001 0.0001, applicable use within galactic chemical evolution models. Contrary to more metal-rich where hot bottom burning is the main driver surface composition, in these lower metallicity effect third dredge-up corrosive second also have strong impact on yields. These metal-poor very create large amounts 4He, 13C, 14N 27Al as well heavy magnesium isotopes 25Mg 26Mg. There...

Context. The existence of ultra-massive white dwarf stars, M WD ≳ 1.05 ⊙ , has been reported in several studies. These dwarfs are relevant for the role they play type Ia supernova explosions, occurrence physical processes asymptotic giant-branch phase, high-field magnetic dwarfs, and double-white-dwarf mergers. Aims. We aim to explore formation ultra-massive, carbon-oxygen core resulting from single stellar evolution. also intend study their evolutionary pulsational properties compare them...

We present an extensive set of detailed stellar models in the mass range 7.7–10.5 M⊙ over metallicity Z= 10−5–0.02. These were produced using Monash University version Mount Stromlo Stellar Structure Program (monstar) and follow evolution from pre-main sequence to first thermal pulse these super asymptotic giant branch stars. A quantitative comparison is made study Siess. Prior this study, only qualitative comparisons code validations existed critical range, large variations literature...

The literature is rich in analysis and results related to thermally pulsing-asymptotic giant branch (TP-AGB) stars, but the problem of instabilities that arise cause divergence models during late stages their evolution rarely addressed. We investigate physical conditions, causes consequences interruption calculations massive AGB stars thermally-pulsing phase. have thoroughly analysed structure a solar metallicity 8.5 mass star described conditions at base convective envelope (BCE) just prior...

Ultra-massive white dwarfs ($\rm M_{WD} \gtrsim 1.05\, M_{\odot}$) are considered powerful tools to study type Ia supernovae explosions, merger events, the occurrence of physical processes in Super Asymptotic Giant Branch (SAGB) phase, and existence high magnetic fields. Traditionally, ultra-massive expected harbour oxygen-neon (ONe) cores. However, new observations recent theoretical studies suggest that progenitors some can avoid carbon burning, leading formation harbouring carbon-oxygen...

Abstract The stellar initial mass function (IMF) plays a crucial role in the determination of number surviving stars galaxies, chemical composition interstellar medium and distribution light galaxies. A key unsolved question is whether IMF universal time space. Here, we use state-of-the-art results evolution to show that our Galaxy made transition from an dominated by massive present-day at early phase formation. Updated wide range metallicities have been implemented binary population...

In this paper, we revisit the problem of determination frequency occurrence galactic nova outbursts which involve an oxygen-neon (ONe) white dwarf. The improvement with respect to previous work on subject derives from fact that use results our evolutionary calculations provide for final mass and chemical profiles intermediate-to-massive primary components close binary systems. particular, stages, such as carbon burning phase, have been carefully followed whole range masses interest. obtained...

The vital importance of composition-dependent low-temperature opacity in low-mass (M < 3Msun) asymptotic giant branch (AGB) stellar models metallicity Z > 0.001 has recently been demonstrated (e.g. Marigo 2002; Ventura & 2010). Its significance to more metal-poor, intermediate mass 2.5Msun) yet be investigated. We show that its inclusion lower-metallicity ([Fe/H] -2) is essential, and there exists no threshold below which molecular may neglected. find it crucial all intermediate-mass...

ABSTRACT We employ the La Plata stellar evolution code, lpcode, to compute first set of constant rest-mass carbon–oxygen ultra-massive white dwarf evolutionary sequences for masses higher than 1.29 M⊙ that fully take into account effects general relativity on their structural and properties. In addition, we lp-pul pulsation code adiabatic g-mode Newtonian pulsations our relativistic equilibrium models. find dwarfs more massive 1.382 become gravitationally unstable with respect effects, being...

Our main goals are to get a deeper insight into the evolution and final fates of intermediate-mass, extremely metal-poor (EMP) stars. We also aim investigate their C, N, O yields. Using Monash University Stellar Evolution code we computed analysed stars metallicity Z = 10^-5 masses between 4 9 M_sun, from sequence until late thermally pulsing (super) asymptotic giant branch, TP-(S)AGB phase. model experience strong envelope enrichment either due second dredge-up, dredge-out phenomenon, or...

The evolution of a star initial mass 10 , and metallicity in Close Binary System (CBS) is followed from its main sequence until an ONe degenerate remnant forms. Restrictions have been made on the characteristics companion as well orbital parameters order to avoid occurrence reversal transfer before carbon ignited core. system undergoes three loss episodes. first second ones are consequence case B Roche lobe overflow. During third episode stellar winds may play role comparable to, or even...

Aims.We compute and analyze the evolution of primordial stars masses at ZAMS between , with without overshooting. Our main goals are to determine nature remnants massive intermediate-mass check influence overshooting in their evolution.

Recently, it has been found that off-center carbon burning in a subset of intermediate-mass stars does not propagate all the way to center, resulting class hybrid CONe cores. The implications significant presence massive degenerate cores have thoroughly explored so far. Here, we consider possibility hosting these might belong close binary system and, eventually, become white dwarfs accreting from nondegenerate companion at rates leading supernova explosion. We computed hydrodynamical phase...

We study the formation and evolution of DA white dwarfs, progenitors which have experienced a late thermal pulse (LTP) shortly after departure from thermally pulsing AGB. To this end, we compute complete an initially 2.7 Mo star all way zero-age main sequence to dwarf stage. find that most original H-rich material post-AGB remnant is burnt during post-LTP evolution, with result that, at entering its cooling track, remaining H envelope becomes 10^-6 in agreement asteroseismological inferences...

Classical novae are stellar explosions with an energy release that is only overcome by supernovae and γ-ray bursts. Theoretical observational evidence suggests these cataclysmic events major sources of the Galactic 15N, 17O, 13C, contribute to abundances 7Li, 26Al, a likely nucleosynthetic endpoint around Ca. However, there reasons believe nuclear signatures have changed during overall history. In this Letter, first addresses nature nova in most primitive, low-metallicity binaries, we show...

The evolution of a zero metallicity star is computed, analyzed and compared with that solar identical ZAMS mass. Our computations range from the main sequence until formation massive oxygen-neon white dwarf. Special attention has been payed to carbon burning in conditions partial degeneracy as well subsequent thermally pulsing Super-AGB phase. latter develops fashion very similar star, consequence significant enrichment metals stellar envelope ensues due so-called third dredge-up episode....

Abstract Getting a better understanding of the evolution and nucleosynthetic yields most metal-poor stars ( Z ≲ 10 −5 ) is critical because they are part big picture history primitive universe. Yet many remaining unknowns stellar lie in birth, life, death these objects. We review intermediate-mass ≤ models existing literature, with particular focus on problem their final fates. emphasise importance mixing episodes between envelope nuclearly processed core, which occur after exhaust central...

Primordial black holes in the asteroid-mass window ($\sim 10^{-16}$ to $10^{-11} \rm M_{\odot}$), which might constitute all dark matter, can be captured by stars when they traverse them at low enough velocity. After being placed on a bound orbit during star formation, repeatedly cross if happens highly eccentric, slow down dynamical friction and end up stellar core. The rate of these captures is highest halos high matter density velocity dispersion, first form redshift $z \sim 20$. We...

Abridged: Observed abundances of extremely metal-poor (EMP) stars in the Halo hold clues for understanding ancient universe. Interpreting these requires theoretical stellar models at low-Z regime. We provide nucleosynthetic yields intermediate-mass Z=$10^{-5}$ between 3 and 7.5 $M_{sun}$, quantify effects uncertain wind rates. expect can be eventually used to assess contribution chemical inventory early universe, help interpret selected C-enhanced EMP stars. By comparing our other existing...

Abridged. We aim to better characterise the evolution and fates, determine updated nucleosynthetic yields of intermediate-mass stars between primordial EMP metallicity (Z=1e-10, 1e-8, 1e-7, 1e-6 1e-5). also probed uncertainties in nucleosynthesis oldest during asymptotic giant branch (AGB) phase. analysed models from their main sequence, through thermally pulsing AGB (TP-AGB), latest stages evolution, using Monash-Mount Stromlo stellar code MONSTAR. The results were post-processed with...

We analyze the impact of initial abundances underlying white dwarf core on nucleosynthesis accompanying classical nova outbursts, in framework hydrodynamic models explosion. Specifically, we take into account chemical stratification dwarf. It turns out that presence a thick CO buffer top ONe-rich core, as results from detailed calculations previous evolution progenitor star, may lead to significant amounts both 7Li and 26Al, after an outburst that, because lack neon isotopes ejecta, would be...