WARM STELLAR MATTER: APPLICATION TO SLOWLY ROTATING COMPACT OBJECTS

2008 ◽  
Vol 23 (05) ◽  
pp. 729-740
Author(s):  
M. D. ALLOY ◽  
D. P. MENEZES
Keyword(s):  
Equations Of State ◽  
Compact Objects ◽  
Zero Temperature ◽  
Stellar Matter

In the present paper we investigate one possible variation on the usual static pulsars: the inclusion of rotation. We use a formalism proposed by Hartle and Thorne to calculate the properties of rotating pulsars with all possible compositions. The calculations were performed for both zero temperature and for fixed entropy equations of state.

scholarly journals Holographic equations of state and astrophysical compact objects

2011 ◽  
Vol 2011 (10) ◽  
Author(s):  
Youngman Kim ◽  
Chang-Hwan Lee ◽  
Ik Jae Shin ◽  
Mew-Bing Wan
Keyword(s):  
Equations Of State ◽  
Compact Objects

Equations of state and phase transitions in stellar matter

2014 ◽  
Author(s):  
Ad. R. Raduta ◽  
F. Gulminelli ◽  
M. Oertel ◽  
J. Margueron ◽  
F. Aymard
Keyword(s):  
Phase Transitions ◽  
Equations Of State ◽  
Stellar Matter

scholarly journals Stability and improved physical characteristics of relativistic compact objects arising from the quadratic term in $$p_r = \alpha \rho ^2 + \beta \rho - \gamma $$

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
S. Thirukkanesh ◽  
Robert S. Bogadi ◽  
Megandhren Govender ◽  
Sibusiso Moyo
Keyword(s):  
Equation Of State ◽  
Gravitational Potential ◽  
Equations Of State ◽  
Quadratic Equation ◽  
Physical Characteristics ◽  
Compact Objects ◽  
Quadratic Term ◽  
Stellar Objects ◽  
Quadratic Equation Of State ◽  
The Stability

AbstractWe investigate the stability and enhancement of the physical characteristics of compact, relativistic objects which follow a quadratic equation of state. To achieve this, we make use of the Vaidya–Tikekar metric potential. This gravitational potential has been shown to be suitable for describing superdense stellar objects. Pressure anisotropy is also a key feature of our model and is shown to play an important role in maintaining stability. Our results show that the combination of the Vaidya–Tikekar gravitational potential used together with the quadratic equation of state provide models which are favourable. In comparison with other equations of state, we have shown that the quadratic equation of state mimics the colour-flavour-locked equation of state more closely than the linear equation of state.

scholarly journals Distinct classes of compact stars based on geometrically deduced equations of state

2021 ◽  
pp. 2150029
Author(s):  
A. C. Khunt ◽  
V. O. Thomas ◽  
P. C. Vinodkumar
Keyword(s):  
Neutron Stars ◽  
Soft Matter ◽  
Equations Of State ◽  
Compact Objects ◽  
Exotic Matter ◽  
Compact Stars ◽  
Spacetime Geometry ◽  
Superdense Stars ◽  
Einstein's Equation ◽  
Envelope Model

We have computed the properties of compact objects like neutron stars based on equation of state (EOS) deduced from a core–envelope model of superdense stars. Such superdense stars have been studied by solving Einstein’s equation based on pseudo-spheroidal and spherically symmetric spacetime geometry. The computed star properties are compared with those obtained based on nuclear matter EOSs. From the mass–radius ([Formula: see text]–[Formula: see text]) relationship obtained here, we are able to classify compact stars in three categories: (i) highly compact self-bound stars that represents exotic matter compositions with radius lying below 9[Formula: see text]km; (ii) normal neutron stars with radius between 9 to 12[Formula: see text]km and (iii) soft matter neutron stars having radius lying between 12 to 20[Formula: see text]km. Other properties such as Keplerian frequency, surface gravity and surface gravitational redshift are also computed for all the three types. This work would be useful for the study of highly compact neutron like stars having exotic matter compositions.

scholarly journals Relativistic Neutron Stars: Rheological Type Extensions of the Equations of State

Symmetry ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 189
Author(s):  
Alexander Balakin ◽  
Alexei Ilin ◽  
Anna Kotanjyan ◽  
Levon Grigoryan
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Equations Of State ◽  
Pressure Profile ◽  
Spherically Symmetric ◽  
Zero Temperature ◽  
New Approach ◽  
Modified Equations

Based on the Rheological Paradigm, we extend the equations of state for relativistic spherically symmetric static neutron stars, taking into consideration the derivative of the matter pressure along the so-called director four-vector. The modified equations of state are applied to the model of a zero-temperature neutron condensate. This model includes one new parameter with the dimensionality of length, which describes the rheological type screening inside the neutron star. As an illustration of the new approach, we consider the rheological type generalization of the non-relativistic Lane–Emden theory and find numerically the profiles of the pressure for a number of values of the new guiding parameter. We have found that the rheological type self-interaction makes the neutron star more compact, since the radius of the star, related to the first null of the pressure profile, decreases when the modulus of the rheological type guiding parameter grows.

TWO EQUATIONS OF STATE CONSIDERING THE THERMAL EFFECT FOR α, β AND ω PHASES OF ZIRCONIUM

2008 ◽  
Vol 22 (03) ◽  
pp. 167-180
Author(s):  
RONGGANG TIAN ◽  
JIUXUN SUN ◽  
CHAO ZHANG ◽  
FULONG WANG
Keyword(s):  
Experimental Data ◽  
Thermal Effect ◽  
Equations Of State ◽  
Zero Point ◽  
Hexagonal Structure ◽  
Zero Temperature ◽  
Β Phase ◽  
Ω Phase ◽  
Α Phase ◽  
Einstein Model

The Baonza and mGLJ equations of state (EOS) modified previously to consider the thermal effect are applied to study the thermodynamic properties of Zirconium (Zr) . It is proposed that the zero-point vibration term should be deleted in a thermal EOS, and the parameters cannot be directly taken as experimental data at a reference temperature, [Formula: see text] and [Formula: see text], but their values at absolute zero temperature, [Formula: see text] and [Formula: see text]. Based on the Einstein model, an approach is proposed to solve [Formula: see text] and [Formula: see text] from [Formula: see text] and [Formula: see text]. For the hcp (α phase), bcc (β phase) and hexagonal structure (ω phase) of Zr , the molar volume (V), isothermal bulk modulus (B) and thermal expansion coefficient (α) was calculated as a function of pressure and temperature. The predictive capabilities of the complete EOS are discussed and compared with experimental data.

scholarly journals Strange stars in energy–momentum-conserved f(R,T) gravity

2020 ◽  
Vol 29 (10) ◽  
pp. 2050075
Author(s):  
G. A. Carvalho ◽  
S. I. Dos Santos ◽  
P. H. R. S. Moraes ◽  
M. Malheiro
Keyword(s):  
Energy Momentum Tensor ◽  
Equations Of State ◽  
Linear Equations ◽  
Momentum Tensor ◽  
Compact Objects ◽  
Strange Stars ◽  
Cosmological Scenario ◽  
Astrophysical Objects ◽  
Tensor Formula ◽  
Tov Equation

For the accurate understanding of compact astrophysical objects, the Tolmann–Oppenheimer–Volkoff (TOV) equation has proved to be of great use. Nowadays, it has been derived in many alternative gravity theories, yielding the prediction of different macroscopic features for such compact objects. In this work, we apply the TOV equation of the energy–momentum–conserved version of the [Formula: see text] gravity theory to strange quark stars. The [Formula: see text] theory, with [Formula: see text] being a generic function of the Ricci scalar [Formula: see text] and trace of the energy–momentum tensor [Formula: see text] to replace [Formula: see text] in the Einstein–Hilbert gravitational action, has shown to provide a very interesting alternative to the cosmological constant [Formula: see text] in a cosmological scenario, particularly in the energy–momentum conserved case (a general [Formula: see text] function does not conserve the energy–momentum tensor). Here, we impose the condition [Formula: see text] to the astrophysical case, particularly the hydrostatic equilibrium of strange stars. We solve the TOV equation by taking into account linear equations of state to describe matter inside strange stars, such as [Formula: see text] and [Formula: see text], known as the MIT bag model, with [Formula: see text] the pressure and [Formula: see text] the energy density of the star, [Formula: see text] constant and [Formula: see text] the bag constant.

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