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Anisotropic stellar structure equations for magnetized strange stars
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作者 Daryel Manreza Paret Jorge Ernesto Horvath Aurora Pérez Mart'nez 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第7期975-985,共11页
The fact that a fermion system in an external magnetic field breaks the spherical symmetry suggests that its intrinsic geometry is axisymmetric rather than spherical. In this work we analyze the impact of anisotropic ... The fact that a fermion system in an external magnetic field breaks the spherical symmetry suggests that its intrinsic geometry is axisymmetric rather than spherical. In this work we analyze the impact of anisotropic pressures, due to the presence of a magnetic field, in the structure equations of a magnetized quark star.We assume a cylindrical metric and an anisotropic energy momentum tensor for the source. We found that there is a maximum magnetic field that a strange star can sustain, closely related to the violation of the virial relations. 展开更多
关键词 magnetic fields -- stars: neutron -- equation of state
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Maximum mass of magnetic white dwarfs
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作者 Daryel Manreza Paret Jorge Ernesto Horvath Aurora Pérez Martínez 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第10期1735-1741,共7页
We revisit the problem of the maximum masses of magnetized white dwarfs (WDs). The impact of a strong magnetic field on the structure equations is addressed. The pressures become anisotropic due to the presence of t... We revisit the problem of the maximum masses of magnetized white dwarfs (WDs). The impact of a strong magnetic field on the structure equations is addressed. The pressures become anisotropic due to the presence of the magnetic field and split into parallel and perpendicular components. We first construct stable solutions of the Tolman-Oppenheimer-Volkoff equations for parallel pressures and find that physical solutions vanish for the perpendicular pressure whenB ≥ 10^13 G. This fact estab- lishes an upper bound for a magnetic field and the stability of the configurations in the (quasi) spherical approximation. Our findings also indicate that it is not possible to obtain stable magnetized WDs with super-Chandrasekhar masses because the val- ues of the magnetic field needed for them are higher than this bound. To proceed into the anisotropic regime, we can apply results for structure equations appropriate for a cylindrical metric with anisotropic pressures that were derived in our previous work. From the solutions of the structure equations in cylindrical symmetry we have con- firmed the same bound for B- 10^13 G, since beyond this value no physical solutions are possible. Our tentative conclusion is that massive WDs with masses well beyond the Chandrasekhar limit do not constitute stable solutions and should not exist. 展开更多
关键词 magnetic fields -- white dwarfs -- equation of state
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Quantum Instability of Magnetized Stellar Objects
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作者 R.González Felipe H.J.Mosquera Cuesta +1 位作者 A.Pérez Martínez H.Pérez Rojas 《Chinese Journal of Astronomy and Astrophysics》 CSCD 2005年第4期399-411,共13页
The equations of state for degenerate electron and neutron gases are studied in the presence of magnetic fields.After including quantum effects in the investigation of the structural properties of these systems,it is ... The equations of state for degenerate electron and neutron gases are studied in the presence of magnetic fields.After including quantum effects in the investigation of the structural properties of these systems,it is found that some hypermagnetized stars can be unstable according to the criterion of stability of pressures.Highly magnetized white dwarfs should collapse producing a supernova type Ia,while superstrong magnetized neutron stars cannot stand their own magnetic field and must implode,too.A comparison of our results with a set of the available observational data of some compact stars is also presented,and the agreement between this theory and observations is verified. 展开更多
关键词 dense matter-equation of state-instabilities-stars:magnetic fields-stars:neutron white dwarfs
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Photoluminescence characteristics of soft PZT 53/47 ceramic doped at A and/or B sites 被引量:3
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作者 M.D.DURRUTHY-RODRíGUEZ J.J.GERVACIO-ARCINIEGA +1 位作者 M.HERNáNDEZ-GARCíA J.M.YánEZ-LIMóN 《Journal of Advanced Ceramics》 SCIE CSCD 2018年第2期109-116,共8页
This study presents the photoluminescence characteristics of the PZT 53/47 system doped at A and/or B sites, with Nb(PZTN), La(PLZT), and Nb–La(PLZTN) in the concentration range from 0.2 to 1.0 molar fraction. The in... This study presents the photoluminescence characteristics of the PZT 53/47 system doped at A and/or B sites, with Nb(PZTN), La(PLZT), and Nb–La(PLZTN) in the concentration range from 0.2 to 1.0 molar fraction. The intensity of the emission bands of the system PZTN is two orders higher than the intensity of the emission bands of the systems PLZT and PLZTN, and these emission bands are located at 1.73 eV(718 nm), 2.56 eV(485 nm), and 2.93 eV(424 nm). The origin of the luminescence in these systems is associated with lead and oxygen vacancies produced during the sintering process. The results from X-ray diffraction(XRD) show a mixture of rhombohedral and tetragonal phases. The system PZTN shows a higher tetragonal phase concentration, while PLZT and PLZTN systems show a higher rhombohedral phase concentration. The cell volume shows an increase with dopant concentration only in the case of the PLZTN system. The band gap energy shows a small variation in the PZTN and PLZTN cases around 3.0 eV, a close value to the band gap energy of the pure PZT 53/47 sample. The system PLZT shows an increasing behavior until 4.41 eV for the higher dopant concentration. 展开更多
关键词 PHOTOLUMINESCENCE PZT ceramics band structure X-ray diffraction(XRD)
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