scholarly journals The neutrino emission from thermal processes in very massive stars in the local universe

2021 ◽  
Vol 503 (4) ◽  
pp. 5965-5975
Author(s):  
N Yusof ◽  
H Abu Kassim ◽  
L G Garba ◽  
N S Ahmad
Keyword(s):  
Massive Stars ◽  
Neutrino Energy ◽  
Neutrino Emission ◽  
Thermal Processes ◽  
Local Universe ◽  
Hydrogen Burning ◽  
Pair Annihilation ◽  
Recombination Processes ◽  
Advanced Stages ◽  
Neutrino Luminosity

ABSTRACT We present a new overview of the life of very massive stars (VMS) in terms of neutrino emission from thermal processes: pair annihilation, plasmon decay, photoneutrino process, bremsstrahlung, and recombination processes in burning stages of selected VMS models. We use the realistic conditions of temperature, density, electron fraction, and nuclear isotropic composition of the VMS. Results are presented for a set of progenitor stars with mass of 150, 200, and 300 M⊙Z = 0.002 and 500 M⊙Z = 0.006 rotating models which are expected to explode as a pair instability supernova at the end of their life except the 300 M⊙ would end up as a black hole. It is found that for VMS, thermal neutrino emission occurs as early as towards the end of hydrogen burning stage due to the high initial temperature and density of these VMS. We calculate the total neutrino emissivity, Qν and luminosity, Lν using the structure profile of each burning stages of the models and observed the contribution of photoneutrino at early burning stages (H and He) and pair annihilation at the advanced stages. Pair annihilation and photoneutrino processes are the most dominant neutrino energy loss mechanisms throughout the evolutionary track of the VMS. At the O-burning stage, the neutrino luminosity ∼1047−48 erg s−1 depending on their initial mass and metallicity are slightly higher than the neutrino luminosity from massive stars. This could shed light on the possibility of using detection of neutrinos to locate the candidates for pair instability supernova in our local universe.

scholarly journals Gravitational Collapse and Neutrino Emission of Population III Massive Stars

2006 ◽  
Vol 31 ◽  
pp. 205-206
Author(s):  
Ken'ichiro Nakazato ◽  
Kohsuke Sumiyoshi ◽  
Shoichi Yamada
Keyword(s):  
Gravitational Collapse ◽  
Massive Stars ◽  
Neutrino Emission ◽  
Population Iii

scholarly journals DDO68-V1: an extremely metal-poor LBV in a void galaxy

2018 ◽  
Vol 14 (S344) ◽  
pp. 392-395
Author(s):  
Yulia Perepelitsyna ◽  
Simon Pustilnik
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Massive Stars ◽  
Rare Event ◽  
Local Universe ◽  
Hii Region ◽  
V Band ◽  
Star Evolution ◽  
Low Metallicity ◽  
Massive Star Evolution

AbstractThe lowest metallicity massive stars in the Local Universe with $Z\sim \left( {{Z}_{\odot }}/50-{{Z}_{\odot }}/30 \right)$ are the crucial objects to test the validity of assumptions in the modern models of very low-metallicity massive star evolution. These models, in turn, have major implications for our understanding of galaxy and massive star formation in the early epochs. DDO68-V1 in a void galaxy DDO68 is a unique extremely metal-poor massive star. Discovered by us in 2008 in the HII region Knot3 with $Z={{Z}_{\odot }}/35\,\left[ 12+\log \left( \text{O/H} \right)\sim 7.14 \right]$, DDO68-V1 was identified as an LBV star. We present here the LBV lightcurve in V band, combining own new data and the last archive and/or literature data on the light of Knot3 over the 30 years. We find that during the years 2008-2011 the LBV have experienced a very rare event of ‘giant eruption’ with V-band amplitude of 4.5 mag ($V\sim {{24.5}^{m}}-{{20}^{m}}$).

scholarly journals The sensitivity of presupernova neutrinos to stellar evolution models

2020 ◽  
Vol 496 (3) ◽  
pp. 3961-3972
Author(s):  
Chinami Kato ◽  
Ryosuke Hirai ◽  
Hiroki Nagakura
Keyword(s):  
Time Evolution ◽  
Stellar Evolution ◽  
Phenomenological Model ◽  
Matter Density ◽  
Neutrino Emission ◽  
Central Density ◽  
Order Of Magnitude ◽  
Neutrino Luminosity

ABSTRACT We examine the sensitivity of neutrino emission to stellar evolution models for a 15 M⊙ progenitor, paying particular attention to a phase prior to the collapse. We demonstrate that the number luminosities in both electron-type neutrinos (νe) and their antipartners ($\bar{\nu }_\mathrm{ e}$) differ by more than an order of magnitude by changing spatial resolutions and nuclear network sizes on stellar evolution models. We also develop a phenomenological model to capture the essential trend of the diversity, in which neutrino luminosities are expressed as a function of central density, temperature, and electron fraction. In the analysis, we show that the neutrino luminosity can be well characterized by these central quantities. This analysis also reveals that the most influential quantity to the time evolution of νe luminosity is matter density, while it is temperature for $\bar{\nu }_\mathrm{ e}$. These qualitative trends will be useful and applicable to constrain the physical states of progenitors at the final stages of stellar evolution from future neutrino observations, although more detailed systematic studies including various mass progenitors are required to assess the applicability.

scholarly journals Core-hydrogen-burning RSGs in the early globular clusters

2015 ◽  
Vol 11 (A29B) ◽  
pp. 473-473
Author(s):  
Dorottya Szécsi ◽  
Jonathan Mackey ◽  
Norbert Langer
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Massive Stars ◽  
Shell Formation ◽  
Low Mass Stars ◽  
Hydrogen Burning ◽  
The Core ◽  
Anomalous Surface ◽  
Low Metallicity ◽  
Low Mass

AbstractThe first stellar generation in galactic globular clusters contained massive low-metallicity stars (Charbonnel et al. 2014). We modelled the evolution of this massive stellar population and found that such stars with masses 100-600 M⊙ evolve into cool RSGs (Szécsi et al. 2015). These RSGs spend not only the core-He-burning phase but even the last few 105 years of the core-H-burning phase on the SG branch. Due to the presence of hot massive stars in the cluster at the same time, we show that the RSG wind is trapped into photoionization confined shells (Mackey et al. 2014). We simulated the shell formation around such RSGs and find them to become gravitationally unstable (Szécsi et al. 2016). We propose a scenario in which these shells are responsible for the formation of the second generation low-mass stars in globular clusters with anomalous surface abundances.

scholarly journals On the significance of mass loss for the evolution of massive stars

1981 ◽  
Vol 59 ◽  
pp. 265-270
Author(s):  
L.R. Yungelson ◽  
A.G. Massevitch ◽  
A.V. Tutukov
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Loss Rate ◽  
Massive Stars ◽  
Mass Loss Rate ◽  
Hydrogen Burning ◽  
B Stars ◽  
The Core ◽  
Input Parameters ◽  
Satisfactory Theory

It is shown that mass loss by stellar wind with rates observed in O, B-stars cannot change qualitatively their evolution in the core hydrogen-burning stage. The effects, that are usually attributed to the mass loss, can be explained by other causes: e.g., duplicity or enlarged chemically homogeneous stellar cores.The significance of mass loss by stellar wind for the evolution of massive stars was studied extensively by numerous authors (see e.g. Chiosi et al. (1979) and references therein). However, the problem is unclear as yet. There does not exist any satisfactory theory of mass loss by stars. Therefore one is usually forced to assume that mass loss rate depends on some input parameters.

scholarly journals Supergiants and their shells in young globular clusters

2018 ◽  
Vol 612 ◽  
pp. A55 ◽  
Author(s):  
Dorottya Szécsi ◽  
Jonathan Mackey ◽  
Norbert Langer
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Second Generation ◽  
Massive Stars ◽  
Low Mass Stars ◽  
Hydrogen Burning ◽  
Mass Budget ◽  
Low Metallicity ◽  
Low Mass ◽  
Galactic Globular Clusters

Context. Anomalous surface abundances are observed in a fraction of the low-mass stars of Galactic globular clusters, that may originate from hot-hydrogen-burning products ejected by a previous generation of massive stars. Aims. We aim to present and investigate a scenario in which the second generation of polluted low-mass stars can form in shells around cool supergiant stars within a young globular cluster. Methods. Simulations of low-metallicity massive stars (Mi ~ 150−600 M⊙) show that both core-hydrogen-burning cool supergiants and hot ionizing stellar sources are expected to be present simulaneously in young globular clusters. Under these conditions, photoionization-confined shells form around the supergiants. We have simulated such a shell, investigated its stability and analysed its composition. Results. We find that the shell is gravitationally unstable on a timescale that is shorter than the lifetime of the supergiant, and the Bonnor-Ebert mass of the overdense regions is low enough to allow star formation. Since the low-mass stellar generation formed in this shell is made up of the material lost from the supergiant, its composition necessarily reflects the composition of the supergiant wind. We show that the wind contains hot-hydrogen-burning products, and that the shell-stars therefore have very similar abundance anomalies that are observed in the second generation stars of globular clusters. Considering the mass-budget required for the second generation star-formation, we offer two solutions. Either a top-heavy initial mass function is needed with an index of −1.71 to −2.07. Alternatively, we suggest the shell-stars to have a truncated mass distribution, and solve the mass budget problem by justifiably accounting for only a fraction of the first generation. Conclusions. Star-forming shells around cool supergiants could form the second generation of low-mass stars in Galactic globular clusters. Even without forming a photoionizaton-confined shell, the cool supergiant stars predicted at low-metallicity could contribute to the pollution of the interstellar medium of the cluster from which the second generation was born. Thus, the cool supergiant stars should be regarded as important contributors to the evolution of globular clusters.

scholarly journals Posters also presented at the Symposium

2016 ◽  
Vol 12 (S329) ◽  
pp. 455-464
Keyword(s):  
Stellar Evolution ◽  
Scaling Laws ◽  
Convection Zone ◽  
Massive Stars ◽  
Convective Boundary ◽  
Hydrodynamic Simulations ◽  
Fundamental Properties ◽  
Mass Entrainment ◽  
Nuclear Burning ◽  
Advanced Stages

I am reporting on our team's progress in investigating fundamental properties of convective shells in the deep stellar interior during advanced stages of stellar evolution. We have performed a series of 3D hydrodynamic simulations of convection in conditions similar to those in the O-shell burning phase of massive stars. We focus on characterizing the convective boundary and the mixing of material across this boundary. Results from 7683 and 15363 grids are encouragingly similar (typically within 20%). Several global quantities, including the rate of mass entrainment at the convective boundary and the driving luminosity, are related by scaling laws. We investigate the effect of several of our assumptions, including the treatment of the nuclear burning driving the convection or that of neutrino cooling. The burning of the entrained material from above the convection zone could have important implications for pre-supernova nucleosynthesis.

scholarly journals The surface and inner temperatures of magnetars

2012 ◽  
Vol 8 (S291) ◽  
pp. 386-388
Author(s):  
Z. F. Gao ◽  
N. Wang ◽  
Q. H. Peng
Keyword(s):  
Magnetic Field ◽  
Neutrino Emission ◽  
Effective Surface ◽  
X Ray ◽  
One To One ◽  
Field Decay ◽  
Neutrino Luminosity ◽  
The Magnetic Field

AbstractAssuming that the timescale of the magnetic field decay is approximately equal to that of the stellar cooling via neutrino emission, we obtain a one-to-one relationship between the effective surface thermal temperature and the inner temperature. The ratio of the effective neutrino luminosity to the effective X-ray luminosity decreases with decaying magnetic field.

scholarly journals Is Stellar Wind Mass Loss During Core Hydrogen Burning Important for Evolution

1991 ◽  
Vol 143 ◽  
pp. 547-547
Author(s):  
R. Blomme ◽  
D. Vanbeveren ◽  
W. Van Rensbergen
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Massive Stars ◽  
Hydrogen Burning

The influence of wind mass loss during core hydrogen burning on the evolution of massive stars can be investigated using a relation between Ṁ-L-M-Teff based on

WSO and the winds of massive stars: the gate to the metal-poor Local Universe

2011 ◽  
pp. 91-96
Author(s):  
Miriam Garcia ◽  
Artemio Herrero ◽  
Francisco Najarro
Keyword(s):  
Massive Stars ◽  
Local Universe
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