New observational data on the internal structure constants of main-sequence stars

2017 ◽  
Vol 468 (3) ◽  
pp. 3342-3346
Author(s):  
İ. Bulut ◽  
A. Bulut ◽  
O. Demircan
Keyword(s):  
Internal Structure ◽  
Observational Data ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Structure Constants

scholarly journals On the Internal Structure of Main-Sequence Stars

1982 ◽  
Vol 69 ◽  
pp. 37-46 ◽  
Author(s):  
Alvaro Giménez ◽  
José M. García-Pelayo
Keyword(s):  
Internal Structure ◽  
Strong Correlation ◽  
Main Sequence ◽  
Theoretical Models ◽  
Eclipsing Binaries ◽  
Main Sequence Stars ◽  
Structure Constants

We present the main results of a study of the observed internal structure constants, k2, for a wide set of eclipsing binaries. From the analysis of the variations in relative positions of the eclipses and the comparison with different theoretical models, we could deduce that the discrepancy, previously reported by several authors between theory and observations, is no longer supported. Moreover, a strong correlation has been found between the evolution of the parameter k2 and the gravity at the surface of the star, g.

On The Radii of Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 49-55 ◽  
Author(s):  
F.A. Catalano ◽  
G. Strazzulla
Keyword(s):  
Observational Data ◽  
Line Width ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Ap Stars

SummaryFrom the analysis of the observational data of about 100 Ap stars, the radii have been computed under the assumption that Ap are main sequence stars. Radii range from 1.4 to 4.9 solar units. These values are all compatible with the Deutsch's period versus line-width relation.

scholarly journals Winds

1993 ◽  
Vol 137 ◽  
pp. 620-633
Author(s):  
K.B. MacGregor
Keyword(s):  
Mass Loss ◽  
Internal Structure ◽  
Physical State ◽  
Main Sequence ◽  
Stellar Atmosphere ◽  
Present Review ◽  
Main Sequence Stars ◽  
Dynamical State ◽  
Stellar Interiors

AbstractIt is by now well known that most main sequence stars continuously lose mass as a consequence of the winds they emit. In addition to affecting the thermal and dynamical state of the stellar atmosphere, such mass loss can also induce changes in the interiors of stars. In the present review, we consider a few of the ways in which sustained, wind-like mass loss can alter the physical state of main sequence stellar interiors by examining the differences in internal structure, composition, and rotation between mass-losing and conservatively evolving stars.

The Internal Structure of Middle Main-Sequence Stars.

1962 ◽  
Vol 135 ◽  
pp. 770 ◽  
Author(s):  
Icko, Jr. Iben ◽  
John R. Ehrman
Keyword(s):  
Internal Structure ◽  
Main Sequence ◽  
Main Sequence Stars

scholarly journals THE FIRST DETAILED ANALYSIS ON THE ASTROPHYSICAL PROPERTIES OF THE ECCENTRIC BINARY V990 HER

2021 ◽  
Vol 57 (2) ◽  
pp. 363-379
Author(s):  
E. Kiran ◽  
V. Bakiş ◽  
H. Bakiş ◽  
Ö. L. Değirmenci
Keyword(s):  
Binary System ◽  
Detailed Analysis ◽  
Internal Structure ◽  
Orbital Period ◽  
Spectroscopic Data ◽  
Main Sequence ◽  
Physical Parameters ◽  
Apsidal Motion ◽  
Structure Constants ◽  
First Time

We present accurate physical parameters of the eccentric binary system V990 Her which has an orbital period of P=8.193315±0.000003 days using its photometric and spectroscopic data. The physical parameters of the components were derived as Teff1=8000±200 K, Teff2=7570±200 K, M1=2.01±0.07 Mʘ, M2=1.83±0.03 Mʘ, R1=2.22±0.02 Rʘ, R2=2.12±0.01 Rʘ, log(L1/Lʘ)=1.25±0.04, log(L2/Lʘ)=1.12±0.05. Our findings revealed that both components are slightly evolved from the zero-age main sequence with an age of 6.3×108 years. We estimated an apsidal motion with a period of U=14683±2936 years in the system and the internal structure constants of the components were derived for the first time.

scholarly journals Cataclysmic Variables: Structure and Evolution

1994 ◽  
Vol 147 ◽  
pp. 420-442
Author(s):  
J.-M. Hameury
Keyword(s):  
Equation Of State ◽  
Internal Structure ◽  
Observational Data ◽  
Main Sequence ◽  
Cataclysmic Variables ◽  
Main Sequence Star

AbstractI discuss the structure and evolution of cataclysmic variables, with a particular emphasis on the influence of the physics used in calculating the internal structure of the secondary. The available observational data is very rich, and can, in principle, be used to constrain the stellar physics. It is found that, in order to explain the lack of systems with periods in the range 2 – 3 hr, it is required that main sequence star become convective for masses below 0.3 M⊙. This has little consequences on the equation of state, but constrains the opacities and the treatment of subphotospheric layers.

Is there large convective-core overshooting in Kepler targets KIC 2837475 and 11081729?

2020 ◽  
Vol 497 (4) ◽  
pp. 4042-4050
Author(s):  
Jianwei Zhang
Keyword(s):  
Internal Structure ◽  
Main Sequence ◽  
Normal Values ◽  
Independent Method ◽  
Observational Constraints ◽  
Main Sequence Stars ◽  
Convective Core ◽  
Best Fitting ◽  
Model Independent ◽  
Fitting Model

ABSTRACT The ratio of small-to-large separations r010 has been widely used in helioseismology and asteroseismology to investigate the internal structure of a star, as it is approximately independent of the structure of the outer layers. Several studies have used this tool to constrain the convective-core overshooting of main-sequence stars (i.e. 0.0 ≤ δov ≤ 0.2). This is consistent with the generally accepted values. However, Yang et al. have proposed that there is large convective-core overshooting in the Kepler targets KIC 2837475 and 11081729: 1.2 ≤ δov ≤ 1.6 and 1.7 ≤ δov ≤ 1.8, respectively. These are much larger than the normal values. Thus, the aim of this study is to re-investigate the ratios of the two stars using a model-independent method with the latest p-mode observations. Our results indicate that there is no robustness for including such a large convective-core overshooting while modelling these two stars. In fact, this leads to over-fitting, and the observational constraints of r010 prefer models with a normal convective-core overshooting (i.e. 0.0 ≤ δov ≤ 0.2) as the candidates for the best-fitting model of KIC 2837475 and 11081729.

scholarly journals Magnetic coronae of active main-sequence stars

2008 ◽  
Vol 4 (S259) ◽  
pp. 357-362 ◽  
Author(s):  
Moira Jardine ◽  
Jean-Francois Donati
Keyword(s):  
Binary System ◽  
Radio Emission ◽  
Solar Corona ◽  
Internal Structure ◽  
Main Sequence ◽  
The Sun ◽  
Coronal Structure ◽  
Main Sequence Stars ◽  
X Ray ◽  
Recent Advances

AbstractThe coronal structure of main sequence stars continues to puzzle us. While the solar corona is relatively well understood, it has become clear that even stars of the same mass as the Sun can display very non-solar coronal behaviour, particularly if they are rapid rotators or in a binary system. At masses greater than and also less than that of the Sun, the non-solar internal structure appears to affect both the geometry and dynamics of the stellar corona and the nature of the X-ray and radio emission. In this talk I will describe some recent advances in our understanding of the structure of the coronae of some of the most active (and interesting) main sequence stars.

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