scholarly journals On the Tachocline Zone Location in the Sun, the Luminosity Transport time scale, the Rotational Inertia and their Time Variation in Standard Solar Evolution Models

2017 ◽  
Vol 13 (1) ◽  
pp. 49-74
Author(s):  
Mandyam N Anandaram
Keyword(s):  
Time Variation ◽  
Time Scale ◽  
Gradual Increase ◽  
Rotational Inertia ◽  
The Sun ◽  
Transport Time ◽  
Photon Diffusion ◽  
Solar Evolution ◽  
Transport Time Scale

Studies with GONG Standard Solar Evolution Models sampling the evolution of the sun from its ZAMS stage show the following. The location of the tachocline zone is nearly fixed as it is not affected by shell burning although it co-moves with   the expansion of the sun up to the present age of 4.6 Gyr. The luminosity transport time scale of the sun is entirely dominated by photon diffusion and during the evolution has decreased from over 204000 years to 187000 years. The rotational inertia of the sun shows a small gradual increase from

scholarly journals Collisional delta-f scheme with evolving background for transport time scale simulations

1999 ◽  
Vol 6 (12) ◽  
pp. 4504-4521 ◽  
Author(s):  
S. Brunner ◽  
E. Valeo ◽  
J. A. Krommes
Keyword(s):  
Time Scale ◽  
Transport Time ◽  
Transport Time Scale

On the photon diffusion time scale for the sun

1992 ◽  
Vol 401 ◽  
pp. 759 ◽  
Author(s):  
R. Mitalas ◽  
K. R. Sills
Keyword(s):  
Time Scale ◽  
Diffusion Time ◽  
The Sun ◽  
Photon Diffusion

scholarly journals Mass-loss varying luminosity and its implication to the solar evolution

2019 ◽  
Vol 15 (S356) ◽  
pp. 403-404
Author(s):  
Negessa Tilahun Shukure ◽  
Solomon Belay Tessema ◽  
Endalkachew Mengistu
Keyword(s):  
Standard Model ◽  
Mass Loss ◽  
Main Sequence ◽  
The Sun ◽  
Solar Mass ◽  
Solar Luminosity ◽  
Solar Evolution

AbstractSeveral models of the solar luminosity, , in the evolutionary timescale, have been computed as a function of time. However, the solar mass-loss, , is one of the drivers of variation in this timescale. The purpose of this study is to model mass-loss varying solar luminosity, , and to predict the luminosity variation before it leaves the main sequence. We numerically computed the up to 4.9 Gyrs from now. We used the solution to compute the modeled . We then validated our model with the current solar standard model (SSM). The shows consistency up to 8 Gyrs. At about 8.85 Gyrs, the Sun loses 28% of its mass and its luminosity increased to 2.2. The model suggests that the total main sequence lifetime is nearly 9 Gyrs. The model explains well the stage at which the Sun exhausts its central supply of hydrogen and when it will be ready to leave the main sequence. It may also explain the fate of the Sun by making some improvements in comparison to previous models.

scholarly journals Solar structure and evolution

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Jørgen Christensen-Dalsgaard
Keyword(s):  
Solar Surface ◽  
Solar Neutrinos ◽  
Solar Interior ◽  
Stellar Structure ◽  
The Sun ◽  
Physical Processes ◽  
Solar Evolution ◽  
Internal Properties ◽  
Atmospheric Phenomena

AbstractThe Sun provides a critical benchmark for the general study of stellar structure and evolution. Also, knowledge about the internal properties of the Sun is important for the understanding of solar atmospheric phenomena, including the solar magnetic cycle. Here I provide a brief overview of the theory of stellar structure and evolution, including the physical processes and parameters that are involved. This is followed by a discussion of solar evolution, extending from the birth to the latest stages. As a background for the interpretation of observations related to the solar interior I provide a rather extensive analysis of the sensitivity of solar models to the assumptions underlying their calculation. I then discuss the detailed information about the solar interior that has become available through helioseismic investigations and the detection of solar neutrinos, with further constraints provided by the observed abundances of the lightest elements. Revisions in the determination of the solar surface abundances have led to increased discrepancies, discussed in some detail, between the observational inferences and solar models. I finally briefly address the relation of the Sun to other similar stars and the prospects for asteroseismic investigations of stellar structure and evolution.

scholarly journals The impact of composition choices on solar evolution: age, helio- and asteroseismology, and neutrinos

2020 ◽  
Vol 498 (2) ◽  
pp. 1992-2000
Author(s):  
Diogo Capelo ◽  
Ilídio Lopes
Keyword(s):  
The Sun ◽  
Fundamental Parameters ◽  
Element Abundances ◽  
Solar Evolution ◽  
Oxygen Cycle ◽  
Potential Impact ◽  
Red Giant ◽  
Neutrino Fluxes ◽  
Neutrino Experiments ◽  
The Impact

ABSTRACT The Sun is the most studied and well-known star, and as such, solar fundamental parameters are often used to bridge gaps in the knowledge of other stars, when these are required for modelling. However, the two most powerful and precise independent methodologies currently available to infer the internal solar structure are in disagreement. We aim to show the potential impact of composition choices in the overall evolution of a star, using the Sun as example. To this effect, we create two Standard Solar Models and a comparison model using different combinations of metallicity and relative element abundances and compare evolutionary, helioseismic, and neutrino-related properties for each. We report differences in age for models calibrated to the same point on the HR diagram, in red giant branch, of more than 1 Gyr, and found that the current precision level of asteroseismic measurements is enough to differentiate these models, which would exhibit differences in period spacing of 1.30–2.58 per cent. Additionally, we show that the measurement of neutrino fluxes from the carbon–nitrogen–oxygen cycle with a precision of around 17 per cent, which could be achieved by the next generation of solar neutrino experiments, could help resolve the stellar abundance problem.

scholarly journals GSC 4019 3345: An A-Type Twin Binary

2013 ◽  
Vol 30 ◽  
Author(s):  
V. Bakış ◽  
H. Bakış ◽  
Z. Eker
Keyword(s):  
Circular Orbit ◽  
Time Scale ◽  
Rotation Velocity ◽  
Young Age ◽  
Synthetic Spectrum ◽  
Evolutionary Status ◽  
Age Difference ◽  
The Sun ◽  
Synchronization Time ◽  
Orbit Modeling

AbstractPhysical dimensions and evolutionary status of the A-type twin binary GSC 4019 3345 are presented. Located at a distance of ~1.1 kpc from the Sun, the system was found to have two components with identical masses (M1,2 = 1.92 M⊙), radii (R1,2 = 1.76 R⊙), and luminosities (log L1,2 = 1.1 L⊙) revolving in a circular orbit. Modeling the components with theoretical evolutionary tracks and isochrones implies a young age (t = 280 Myr) for the system, which is bigger than the synchronization time scale but smaller than the circularization time scale. Nevertheless, synthetic spectrum models revealed components’ rotation velocity of Vrot12 = 70 km s−1, that is about three times higher than their synchronization velocity. No evidence is found for an age difference between the components.

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