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 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 Synthetic clusters of massive stars to test stellar evolution models

2015 ◽  
Vol 12 (S316) ◽  
pp. 355-356
Author(s):  
Cyril Georgy ◽  
Sylvia Ekström
Keyword(s):  
Time Evolution ◽  
Stellar Evolution ◽  
Massive Stars ◽  
Stellar Populations ◽  
Stellar Models

AbstractDuring the last few years, the Geneva stellar evolution group has released new grids of stellar models, including the effect of rotation and with updated physical inputs (Ekström et al. 2012; Georgy et al. 2013a, b). To ease the comparison between the outputs of the stellar evolution computations and the observations, a dedicated tool was developed: the Syclist toolbox (Georgy et al. 2014). It allows to compute interpolated stellar models, isochrones, synthetic clusters, and to simulate the time-evolution of stellar populations.

scholarly journals Pre-Collapse Evolution of Galactic Globular Clusters

1996 ◽  
Vol 174 ◽  
pp. 365-366
Author(s):  
Toshiyuki Fukushige ◽  
Douglas C. Heggie
Keyword(s):  
Mass Spectrum ◽  
Mass Loss ◽  
Stellar Evolution ◽  
Globular Clusters ◽  
Star Clusters ◽  
Early Evolution ◽  
Initial Structure ◽  
Spherically Symmetric ◽  
Order Of Magnitude ◽  
Model Star

We investigated collisionless aspects of the early evolution of model star clusters. The effects of mass loss through stellar evolution and of a steady tidal field are modelled using N-body simulations. Our results (which depend on the assumed initial structure and the mass spectrum) agree qualitatively with those of Chernoff & Weinberg (1990), who used a Fokker-Planck model with a spherically symmetric tidal cutoff. For those systems which are disrupted, the lifetime to disruption generally exceeds that found by Chernoff & Weinberg, sometimes by as much as an order of magnitude.

scholarly journals Effects of stellar density on the photoevaporation of circumstellar discs

2020 ◽  
Vol 501 (2) ◽  
pp. 1782-1790
Author(s):  
Francisca Concha-Ramírez ◽  
Martijn J C Wilhelm ◽  
Simon Portegies Zwart ◽  
Sierk E van Terwisga ◽  
Alvaro Hacar
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Molecular Cloud ◽  
Stellar Dynamics ◽  
Observational Evidence ◽  
Orion Nebula ◽  
Environmental Processes ◽  
Order Of Magnitude ◽  
Magnitude Difference ◽  
Stellar Density

ABSTRACT Circumstellar discs are the precursors of planetary systems and develop shortly after their host star has formed. In their early stages, these discs are immersed in an environment rich in gas and neighbouring stars, which can be hostile for their survival. There are several environmental processes that affect the evolution of circumstellar discs, and external photoevaporation is arguably one of the most important ones. Theoretical and observational evidence point to circumstellar discs losing mass quickly when in the vicinity of massive, bright stars. In this work, we simulate circumstellar discs in clustered environments in a range of stellar densities, where the photoevaporation mass-loss process is resolved simultaneously with the stellar dynamics, stellar evolution, and the viscous evolution of the discs. Our results indicate that external photoevaporation is efficient in depleting disc masses and that the degree of its effect is related to stellar density. We find that a local stellar density lower than 100 stars pc−2 is necessary for discs massive enough to form planets to survive for 2.0 Myr. There is an order of magnitude difference in the disc masses in regions of projected density 100 versus 104 stars pc−2. We compare our results to observations of the Lupus clouds, the Orion Nebula Cluster, the Orion Molecular Cloud-2, Taurus, and NGC 2024, and find that the trends observed between region density and disc masses are similar to those in our simulations.

scholarly journals Evidence for Stellar Evolution in Mira Variables

1998 ◽  
Vol 11 (1) ◽  
pp. 356-356
Author(s):  
Patricia A Whitelock
Keyword(s):  
Mass Loss ◽  
Real Time ◽  
Time Evolution ◽  
Stellar Evolution ◽  
Evolutionary Status ◽  
Late Type ◽  
Chemical Changes ◽  
Mira Variables ◽  
Late Stages ◽  
Insight Into

After briefly reviewing our understanding of Miras and their evolutionary status, three aspects of real-time evolution in these and related stars are examined: 1.Chemical changes (O-rich to C-rich) due to third dredge-up,2.Period changes due to the effects of the helium shell-flash,3.The existence of ‘fossil’ dust and gas shells. Studies of resolved gas and dust shells are highlighted as particularly interesting. They will enable us to examine the mass-loss histories of many late-type stars over the last ten thousand years or so. Such observations have only recently become technically feasible and they are expected to provide important new insight into the late stages of stellar evolution.

scholarly journals Gamma Ray Bursts and Stellar Evolution

2017 ◽  
Vol 45 ◽  
pp. 1760008
Author(s):  
Kauan D. Marquez ◽  
Débora P. Menezes
Keyword(s):  
Stellar Evolution ◽  
Gamma Ray ◽  
Equations Of State ◽  
Hydrostatic Equilibrium ◽  
Gamma Ray Bursts ◽  
Compact Stars ◽  
Quark Star ◽  
Equilibrium Equations ◽  
Order Of Magnitude ◽  
Effective Models

The phenomenon that originates gamma ray bursts (GRBs) remains undefined. In this work the conversion of a hadronic star into a quark star is discussed as one of the possible causes of GRBs. Effective models are used to describe the compact stars and to obtain their equations of state. Macroscopic properties, such baryonic and gravitational masses, of both types of stars are then obtained from the solution of the hydrostatic equilibrium equations. The relation between this values allows to calculate the amount of energy possibly released in this process. The obtained results are then compared to actual GRB observational data, and are within the observational order of magnitude.

The time evolution of vertical ground movements in the Campei Flegrei caldera: a kinetic phenomenological model

1989 ◽  
Vol 39 (1) ◽  
pp. 41-53 ◽  
Author(s):  
Massimo Cortini ◽  
Alfonso M. Liquori ◽  
Edoardo Del Pezzo ◽  
Annamaria Nassisi
Keyword(s):  
Time Evolution ◽  
Phenomenological Model ◽  
Ground Movements ◽  
Vertical Ground
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