scholarly journals Structural properties of charged compact stars with color-flavor-locked quarks matter

2021 ◽  
Author(s):  
M. K. Jasim ◽  
Anirudh Pradhan ◽  
Ayan Banerjee ◽  
Takol Tangphati ◽  
Grigoris Panotopoulos
Keyword(s):  
Equation Of State ◽  
Structural Properties ◽  
Electric Charge ◽  
Mass Density ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Central Mass ◽  
Quark Stars ◽  
The Impact ◽  
Tov Equation

The observations of pulsars with masses close to [Formula: see text] have put strong constraints on the equation-of-state (EoS) of neutron-rich matter at supranuclear densities. Moreover, the exact internal composition of those objects is largely unknown to us. Aiming to reach the [Formula: see text] limit, here we investigate the impact of electric charge on properties of compact stars assuming that the charge distribution is proportional to the mass density. The study is carried out by solving the Tolman–Oppenheimer–Volkoff (TOV) equation for a well-motivated exotic quark matter in the color-flavor-locked (CFL) phase of color superconductivity. The existence of the CFL phase may be the true ground state of hadronic matter with the possibility of the existence of a pure stable quark star (QS). Concerning the equation-of-state, we obtain structural properties of quark stars and compute the mass, the radius as well as the total electric charge of the star. We analyze the dependence of the physical properties of these QSs depending on the free parameters with special attention on mass–radius relation. We also briefly discuss the mass versus central mass density [Formula: see text] relation for stability, the effect of electric charge and compactness. Finally, our results are compared with the recent observations data on mass–radius relationship.

scholarly journals Temperature oscillations of a gas moving close to circular geodesic in Reissner–Nordström spacetime

2019 ◽  
Vol 28 (04) ◽  
pp. 1950059 ◽  
Author(s):  
Leandro Cesar Mehret ◽  
Gilberto Medeiros Kremer
Keyword(s):  
Black Holes ◽  
Electric Charge ◽  
Periodic Oscillation ◽  
Compact Stars ◽  
Quark Stars ◽  
Temperature Oscillations ◽  
Inverse Effect ◽  
Low Mass ◽  
X Ray Binaries

The objective of this work is to analyze the temperature oscillations that occur in a gas in a circular motion under the action of a Reissner–Nordström gravitational field, verifying the effect of the charge term of the metric on the oscillations. The expression for temperature oscillations follows from Tolman’s law written in Fermi normal coordinates for a comoving observer. The motion of the gas is close to geodesic so the equation of geodesic deviation was used to obtain the expression for temperature oscillations. Then these oscillations are calculated for some compact stars, quark stars, black holes and white dwarfs, using values of electric charge and mass from models found in the literature. Comparing the various models analyzed, it is possible to verify that the role of the charge is the opposite of the mass. While the increase of the mass produces a reduction in the frequencies, amplitude and, in the ratio between the frequencies, the increase of the electric charge produces the inverse effect. In addition, it is shown that if the electric charge is proportional to the mass, the ratio between the frequencies does not depend on the mass, but only on the proportionality factor between charge and mass. The ratios between the frequencies for all the models analyzed (except for supermassive black holes in the extreme limit situations) are close to the [Formula: see text] ratio for twin peak quasi-periodic oscillation (QPO) frequencies, observed in many galactic black holes and neutron star sources in low-mass X-ray binaries.

scholarly journals COLD DENSE BARYONIC MATTER AND COMPACT STARS

2011 ◽  
Vol 26 (25) ◽  
pp. 4311-4334 ◽  
Author(s):  
HYUN KYU LEE ◽  
MANNQUE RHO ◽  
SANG-JIN SIN
Keyword(s):  
Effective Field ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Baryonic Matter ◽  
Mass Generation ◽  
Quark Stars ◽  
Proton Mass ◽  
Starting Point ◽  
Basic Physics ◽  
To Come

Probing dense hadronic matter is thus far an uncharted field of physics. Here we give a brief summary of the highlights of what has been so far accomplished and what will be done in the years ahead by the World Class University III Project at Hanyang University in the endeavor to unravel and elucidate the multifacet of the cold dense baryonic matter existing in the interior of the densest visible stable object in the universe, i.e. neutron stars, strangeness stars and/or quark stars, from a modest and simplified starting point of an effective field theory modeled on the premise of QCD as well as from a gravity dual approach of hQCD. The core of the matter of our research is the possible origin of the ~ 99% of the proton mass that is to be accounted for and how the "vacuum" can be tweaked so that the source of the mass generation can be uncovered by measurements made in terrestrial as well as space laboratories. Some of the issues treated in the program concern what can be done — both theoretically and experimentally — in anticipation of what's to come for basic physics research in Korea.

scholarly journals MAXIMUM MASS OF A CLASS OF COLD COMPACT STARS

2006 ◽  
Vol 15 (03) ◽  
pp. 405-418 ◽  
Author(s):  
R. SHARMA ◽  
S. KARMAKAR ◽  
S. MUKHERJEE
Keyword(s):  
Equation Of State ◽  
Boundary Conditions ◽  
Prior Knowledge ◽  
Surface Density ◽  
Equations Of State ◽  
Compact Stars ◽  
Central Density ◽  
Maximum Mass ◽  
Simple Method ◽  
Tov Equation

We calculate the maximum mass of the class of compact stars described by the Vaidya–Tikekar27 model. The model permits a simple method of systematically fixing bounds on the maximum possible mass of cold compact stars with a given value of radius or central density or surface density. The relevant equations of state are also determined. Although simple, the model is capable of describing the general features of the recently observed very compact stars. For the calculation, no prior knowledge of the equation of state (EOS) is required. This is in contrast to earlier calculations for maximum mass which were done by choosing first the relevant EOSs and using those to solve the TOV equation with appropriate boundary conditions. The bounds obtained by us are comparable and, in some cases, more restrictive than the earlier results.

scholarly journals The influence of bone quality on radiological outcome in 50 consecutive acetabular fractures treated with a pre-contoured anatomic suprapectineal plate

2021 ◽  
Author(s):  
Maximilian J. Hartel ◽  
Tareq Naji ◽  
Florian Fensky ◽  
Frank O. Henes ◽  
Darius M. Thiesen ◽  
...  
Keyword(s):  
Total Hip Arthroplasty ◽  
Bone Mass ◽  
Bone Quality ◽  
Hip Arthroplasty ◽  
Mass Density ◽  
Acetabular Fractures ◽  
Bone Mass Density ◽  
Radiological Outcome ◽  
Total Hip ◽  
The Impact

Abstract Purpose To investigate the range of indications of an anatomical-preshaped three-dimensional suprapectineal plate and to assess the impact of the bone mass density on radiologic outcomes in different types of acetabular fractures. Patients and methods A consecutive case series of 50 acetabular fractures (patient age 69 ± 23 years) treated with suprapectineal anatomic plates were analyzed in a retrospective study. The analysis included: Mechanism of injury, fracture pattern, surgical approach, need for additional total hip arthroplasty, intra- or postoperative complications, as well as bone mass density and radiological outcome on postoperative computed tomography. Results Most frequently, anterior column fracture patterns with and without hemitransverse components as well as associated two column fractures were encountered. The anterior intrapelvic approach (AIP) was used in 98% (49/50) of the cases as primary approach with additional utilization of the first window of the ilioinguinal approach in 13/50 cases (26%). Determination of bone density revealed impaired bone quality in 70% (31/44). Postoperative steps and gaps were significantly greater in this subgroup (p < 0.05). Fracture reduction quality for postoperative steps revealed anatomic results in 92% if the bone quality was normal and in 46% if impaired (p < 0.05). In seven cases (14%), the plate was utilized in combination with acute primary arthroplasty. Conclusion A preshaped suprapectineal plate provides good radiological outcomes in a variety of indications in a predominantly geriatric cohort. Impaired bone quality has a significantly higher risk of poor reduction results. In cases with extensive joint destruction, the combination with total hip arthroplasty was a valuable option.

QCD constraints on the equation of state for compact stars

2016 ◽  
Vol 956 ◽  
pp. 813-816
Author(s):  
E.S. Fraga ◽  
A. Kurkela ◽  
J. Schaffner-Bielich ◽  
A. Vuorinen
Keyword(s):  
Equation Of State ◽  
Compact Stars

scholarly journals Gluon condensates, quark matter equation of state and quark stars

1994 ◽  
Vol 63 (4) ◽  
pp. 681-688 ◽  
Author(s):  
A. Mishra ◽  
H. Mishra ◽  
P. K. Panda ◽  
S. P. Misra
Keyword(s):  
Equation Of State ◽  
Quark Matter ◽  
Quark Stars ◽  
Gluon Condensates

OF CHARGED STARS AND CHARGED BLACK HOLES

2004 ◽  
Vol 13 (07) ◽  
pp. 1375-1379 ◽  
Author(s):  
MANUEL MALHEIRO ◽  
RODRIGO PICANÇO ◽  
SUBHARTHI RAY ◽  
JOSÉ P. S. LEMOS ◽  
VILSON T. ZANCHIN
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Charged Particle ◽  
Equation Of State ◽  
Mass Density ◽  
Compact Star ◽  
Maximum Amount ◽  
Stellar Structure ◽  
Charged Black Holes ◽  
Polytropic Equation

Effect of maximum amount of charge a compact star can hold, is studied here. We analyze the different features in the renewed stellar structure and discuss the reasons why such huge charge is possible inside a compact star. We studied a particular case of a polytropic equation of state (EOS) assuming the charge density is proportional to the mass density. Although the global balance of force allows a huge charge, the electric repulsion faced by each charged particle forces it to leave the star, resulting in the secondary collapse of the system to form a charged black hole.

scholarly journals Structural Properties of G,T-Parallel Duplexes

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Anna Aviñó ◽  
Elena Cubero ◽  
Raimundo Gargallo ◽  
Carlos González ◽  
Modesto Orozco ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Structural Properties ◽  
Theoretical Calculations ◽  
Md Simulations ◽  
Theoretical Studies ◽  
Duplex Structure ◽  
Strong Stabilization ◽  
The Stability ◽  
The Impact

The structure of G,T-parallel-stranded duplexes of DNA carrying similar amounts of adenine and guanine residues is studied by means of molecular dynamics (MD) simulations and UV- and CD spectroscopies. In addition the impact of the substitution of adenine by 8-aminoadenine and guanine by 8-aminoguanine is analyzed. The presence of 8-aminoadenine and 8-aminoguanine stabilizes the parallel duplex structure. Binding of these oligonucleotides to their target polypyrimidine sequences to form the corresponding G,T-parallel triplex was not observed. Instead, when unmodified parallel-stranded duplexes were mixed with their polypyrimidine target, an interstrand Watson-Crick duplex was formed. As predicted by theoretical calculations parallel-stranded duplexes carrying 8-aminopurines did not bind to their target. The preference for the parallel-duplex over the Watson-Crick antiparallel duplex is attributed to the strong stabilization of the parallel duplex produced by the 8-aminopurines. Theoretical studies show that the isomorphism of the triads is crucial for the stability of the parallel triplex.

scholarly journals Quadrupole moments of rotating compact stars

2012 ◽  
Vol 8 (S291) ◽  
pp. 536-536
Author(s):  
Martin Urbanec ◽  
John Miller ◽  
Zdenek Stuchlik
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Strange Star ◽  
Compact Stars ◽  
Quadrupole Moments ◽  
Strange Stars

AbstractWe present quadrupole moments of rotating neutron and strange stars calculated using standard Hartle Thorne approach. We demonstrate differences between neutron and strange star parameters connected with quadrupole moments and how this parameters could be, in the case of neutron stars, approximated almost independently on neutron star equation of state.

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