Prof. Ali A . Taani
Al-Balqa Applied University, Physics, Faculty Member
- Al-Balqa Applied University, Dept. of Applied Sciences, Faculty Memberadd
- Astrophysicistedit
We have collected the parameter of 38 neutron stars (NSs) in binary systems with spin periods and measured masses. By adopting the Boot-strap method, we reproduced the procedure of mass calculated for each system separately, to determine... more
We have collected the parameter of 38 neutron stars (NSs) in binary systems with spin periods and measured masses. By adopting the Boot-strap method, we reproduced the procedure of mass calculated for each system separately, to determine the truly mass distribution of the NS that obtained from observation. We also applied the Monte-Carlo simulation and introduce the characteristic spin period 20 ms, in order to distinguish between millisecond pulsars (MSPs) and less recycled pulsars. The mass distributions of MSPs and the less recycled pulsars could be fitted by a Gaussian function as 1.45±0.42 M⊙ and 1.31±0.17 M⊙ (with 1σ) respectively. As such, the MSP masses are heavier than those in less recycled systems by factor of ~ 0.13M⊙, since the accretion effect during the recycling process.
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The dynamical interaction between binary systems is crucial in understanding the nature of orbital motion under the influence of gravitational potential. In our study, we focused on investigating the effects of dynamical forces on the... more
The dynamical interaction between binary systems is crucial in understanding the nature of orbital motion under the influence of gravitational potential. In our study, we focused on investigating the effects of dynamical forces on the regularity of binary pulsar orbits, which represent a pure two-body system. To incorporate the necessary time dependence and have a regular 3-D axisymmetric potential, we utilized the Rebound package as a numerical integrator. This package integrates the motion of particles under the influence of gravity, allowing for changing orbital parameters at a given instant, and providing a variety of integrators to be used. By analyzing the regularity properties of binaries and their sensitivity to initial conditions, we gained insight into the importance of considering even small perturbations to the system, as they can lead to significant changes in its dynamics.
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We have studied several neutron star high-mass X-ray binaries (HMXBs) with super-giant (SG) companions using a wind-fed binary model associated with the magnetic field. By using the concept of torque balance, the magnetic field parameter... more
We have studied several neutron star high-mass X-ray binaries (HMXBs) with super-giant (SG) companions using a wind-fed binary model associated with the magnetic field. By using the concept of torque balance, the magnetic field parameter determines the mass accretion rate. This would help us to consider the relationship between wind velocity and mass-loss rate. These parameters significantly improve our understanding of the accretion mechanism. The wind velocity is critical in determining the X-ray features. This can be used to identify the ejection process and the stochastic variations in their accretion regimes. However, even in systems with a long orbital period, an accretion disk can be created when the wind velocity is slow. This will allow the HMXB of both types, SG and Be, to be better characterised by deriving accurate properties from these binaries. In addition, we have performed segmentation in the parameter space of donors intended for several SG-HMXB listed in our sample...
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It has been proposed multiple times to use the neutron star (NS) in high-mass X-ray binaries (HMXBs) as an orbiting X-ray probe embedded in the wind-fed of its supergiant (SG) companion in order to constrain the stellar line-driven wind... more
It has been proposed multiple times to use the neutron star (NS) in high-mass X-ray binaries (HMXBs) as an orbiting X-ray probe embedded in the wind-fed of its supergiant (SG) companion in order to constrain the stellar line-driven wind from the SG. We demonstrate how to combine various observables of HMXBs from the X-ray accretion luminosity produced by the wind-fed NS, in order to estimate and constrain the age of the donors. This would help us to study the stellar evolution track for each donor model. Since the evolution of massive stars is essentially determined by mass loss, and that direct measures of mass-loss rates suffer from important uncertainties due to the unknown micro-structure of the wind.
We examine the binding energy due to the dynamical process in close binary systems and investigate the possible companion sufficient to induce their orbital parameters. The deterministic of this interaction has a strong sensitivity to the... more
We examine the binding energy due to the dynamical process in close binary systems and investigate the possible companion sufficient to induce their orbital parameters. The deterministic of this interaction has a strong sensitivity to the equation of state associated with their initial conditions. This behavior will mimic the usually considered amount of accreted matter (delat M~ 0.2M) and indicates the<br> increasing the gravitational mass contribution for the MSP.
Research Interests: Physics and Astrophysics
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In this work, the orbital elements are improved and the total masses of the three close visual binary systems CVBSs: HIP 11352, HIP 70973, and HIP 72479 are precisely calculated. The calculations were performed based on an assessment of... more
In this work, the orbital elements are improved and the total masses of the three close visual binary systems CVBSs: HIP 11352, HIP 70973, and HIP 72479 are precisely calculated. The calculations were performed based on an assessment of the latest Gaia DR2 and Hipparcos trigonometric parallax measurements. The morphology and kinematics of orbits are fitted to the observational data available in the Fourth Catalogue of Interferometric Measurements of Binary Stars, and compared with the earlier orbits published in the Sixth Catalog of Orbits of Visual Binary Stars. The computation of orbital elements allows the determination and estimation of the mass sums for the three systems as: 1.81 ± 0.17 M ⊙ , 1.83 ± 0.07 M ⊙ , and 1.61 ± 0.26 M ⊙ for HIP 11352, HIP 70973, and HIP 72479 respectively. This suggests that these systems belong to the main sequence stars for both components. This will provide valuable insights into the evolution paths of these systems.
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The aspect of formation and evolution of the recycled pulsar (PSR J0737-3039 A/B) is investigated, taking into account the contributions of accretion rate, radius and spin-evolution diagram (í µí°µ–í µí± diagram) in the double pulsar... more
The aspect of formation and evolution of the recycled pulsar (PSR J0737-3039 A/B) is investigated, taking into account the contributions of accretion rate, radius and spin-evolution diagram (í µí°µ–í µí± diagram) in the double pulsar system. Accepting the spin-down age as a rough estimate (or often an upper limit) of the true age of the neutron star, we also impose the restrictions on the radius of this system. We calculate the radius of the recycled pulsar PSR J0737-3039 A ranges approximately from 8.14 to 25.74 km, and the composition of its neutron star nuclear matters is discussed in the mass-radius diagram.
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ABSTRACT We give a brief review on the neutron star spin frequency and its relation to the kHz QPOs. A simple power law relation can be applicable for the Atoll and Z sources with the slightly different power index, e.g. ν1 ~... more
ABSTRACT We give a brief review on the neutron star spin frequency and its relation to the kHz QPOs. A simple power law relation can be applicable for the Atoll and Z sources with the slightly different power index, e.g. ν1 ~ 700(Hz)(ν2/1000)1.8; However, for the two accretion induced millisecond X-ray pulsars, Sax J 1808.4-3658 and XTE 1807-294, their low values of twin kHz QPO separations make them different from the other QPO sources. In addition, there are not found the clear relation between a spin frequency and the twin kHz QPO separation, which seems to hint that the beat model for kHz QPOs confronts the difficulty. The kHz QPO separations are not constant, varied up and down with accretion rate, so the models that follow this tendency are the relativistic precession model by Stella &amp; Vietri and the Alfvën wave oscillation model by Zhang. Averagely, the ratio of upper kHz QPO frequency to the lower one is very close to 1.5, then for Cir X-1 this ratio (~ 3) is unusual higher than those of the other sources.
Research Interests: Physics and Neutron Stars
We present a study of the observational properties of Millisecond Pulsars (MSPs) by way of their magnetic fields, spin periods and masses. These measurements are derived through the scenario of Accretion Induced Collapse (AIC) of white... more
We present a study of the observational properties of Millisecond Pulsars (MSPs) by way of their magnetic fields, spin periods and masses. These measurements are derived through the scenario of Accretion Induced Collapse (AIC) of white dwarfs (WDs) in stellar binary systems, in order to provide a greater understanding of the characteristics of MSP populations. In addition, we demonstrate a strong evolutionary connection between neutron stars and WDs with binary companions from a stellar binary evolution perspective via the AIC process.
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Neutron star parameters, e.g. mass, radius and magnetic field, can be constrained by the observations of kHz quasi-periodic oscillations (QPOs), which show the information close to the surface of neutron stars (NSs) in the accreting... more
Neutron star parameters, e.g. mass, radius and magnetic field, can be constrained by the observations of kHz quasi-periodic oscillations (QPOs), which show the information close to the surface of neutron stars (NSs) in the accreting binary systems. The high QPO frequency will leak out the physics around the inner disk boundary, where the physics in a strong gravity regime will effect. By means of the twin kHz QPO detections, which are interpreted as the Keplerian orbital motions near NSs, the methods of determining NS mass and radius are introduced.
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The various types of pulsars are classified in the magnetic and spin period (B-P) diagram, by which one can recognize their properties there. We also investigate the relation of radio pulsars and X-ray neutron stars, and their... more
The various types of pulsars are classified in the magnetic and spin period (B-P) diagram, by which one can recognize their properties there. We also investigate the relation of radio pulsars and X-ray neutron stars, and their distribution characteristics, implying their evolution links. B-P diagram is divided by the special lines, e.g. spin-up line and "death line", which indicate the evolution information of pulsars. Like Hertzsprung-Russell (H-R) diagram of showing the stellar evolution or "lives of stars", we try to develop B-P diagram as a function of representing the evolution track of neutron star.
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We presented a method useful for estimating parallaxes of visually close binary stars (VCBS). The method depends on atmospheric modeling of the components of the VCBS. We construct model atmospheres by using a grid of Kurucz solar... more
We presented a method useful for estimating parallaxes of visually close binary stars (VCBS). The method depends on atmospheric modeling of the components of the VCBS. We construct model atmospheres by using a grid of Kurucz solar metalicity blanketed models1, which can be applied to calculate the synthetic spectral energy distribution for each component of the binary separately. In addition to study the entire system. However, the entire observational spectral energy distribution of the system was used as a reference for the comparison with the synthetic ones. We choose Hip4809 system to investigate the method, and we also study its physical and geometrical parameters. The new parallax of the system was estimated as π = 40.32 ± 5.00 mas, which disagrees with the Hipparcos parallax measurement (13.94 ± 0.90 mas). Furthermore the model atmosphere parameters of the components of the system were derived as: [Formula: see text], [Formula: see text], log ga = 4.50 ± 0.13, log gb = 4.50 ±...
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ABSTRACT We examine the theory of generation order parameters. Three kinds of generation order parameters are introduced, which describe the production of high-energy γ photons in a cascade process scenario. We find a correlation between... more
ABSTRACT We examine the theory of generation order parameters. Three kinds of generation order parameters are introduced, which describe the production of high-energy γ photons in a cascade process scenario. We find a correlation between the average power-law photon index Γ and spin-down rate in 38 common FERMI γ-ray pulsars, and find that the third generation order parameter, which implies that the magnetic field may have the most significant effect on the high-energy γ photon absorption in the cascade processes, is the best one. The statistical work shows that the theory of generation order parameters can be applied to describe the the γ-ray pulsar radiation mechanisms in the cascade processes.
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The study of variation of measured cyclotron lines is of fundamental importance to understand the physics of the accretion process in magnetized neutron star systems. We investigate the magnetic field formation, evolution and distribution... more
The study of variation of measured cyclotron lines is of fundamental importance to understand the physics of the accretion process in magnetized neutron star systems. We investigate the magnetic field formation, evolution and distribution for several High- Mass X-ray Binaries (HMXBs). We focus our attention on the cyclotron lines that have been detected in HMXB classes in their X-ray spectra. As has been correctly pointed out, several sources show variation in cyclotron lines, this can result due to the effect of accretion dynamics, and hence that would reflect the magnetic field characteristics. Besides, the difference in time scales of variation of accretion rate and different type of companion can be used to distinguish between magnetized neutron stars.
This study presents a comprehensive chemo-dynamical analysis of LAMOST J1109+0754, a bright (V = 12.8), extremely metal-poor (FeH = -3.17) star, with a strong r-process enhancement (EuFe = +0.94 ± 0.12). Our results are based on the 7-D... more
This study presents a comprehensive chemo-dynamical analysis of LAMOST J1109+0754, a bright (V = 12.8), extremely metal-poor (FeH = -3.17) star, with a strong r-process enhancement (EuFe = +0.94 ± 0.12). Our results are based on the 7-D measurements supplied by Gaia and the chemical composition derived from a high-resolution (R∼ 110,000), high signal-to-noise ratio (S/N ∼ 60) optical spectrum obtained by the 2.4 m Automated Planet Finder Telescope at Lick Observatory. We obtain chemical abundances of 31 elements (from lithium to thorium). The abundance ratios (XFe) of the light-elements (Z ⩽ 30) suggest a massive Population III progenitor in the 13.4-29.5 M_⊙ mass range. The heavy-element (30 < Z ⩽ 90) abundance pattern of J1109+075 agrees extremely well with the scaled-Solar r-process signature. We have developed a novel approach to trace the kinematic history and orbital evolution of J1109+0754 with a cOsmologically deRIved timE-varyiNg Galactic poTential (the ORIENT) construct...
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The measured characteristics of binary pulsars provide valuable insights into the evolution of these systems. We study the aspects of binary evolution particularly relevant to binary Millisecond Pulsars (MSPs), and the formation of close... more
The measured characteristics of binary pulsars provide valuable insights into the evolution of these systems. We study the aspects of binary evolution particularly relevant to binary Millisecond Pulsars (MSPs), and the formation of close binaries involving degenerate stars through a spin-evolution diagram (spin-up line). For this task, we use a wide variety of binaries, including those with compact components that observed in different energy bands, which we analyze them according to the spin-up line. Their formation and evolution over timescales of binary evolution models are investigated in order to grab any constraint on their evolution, and to estimate the masses of neutron stars with different mass-transfer histories.
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With the advent of large astronomical surveys, the need of identification of the most interesting astrophysical object is required. In this work we focus on extracting red giant metal-poor stars from the LAMOST DR5. We then query the 5-D... more
With the advent of large astronomical surveys, the need of identification of the most interesting astrophysical object is required. In this work we focus on extracting red giant metal-poor stars from the LAMOST DR5. We then query the 5-D space coordinates from the Gaia DR2 to investigate their energy-action space. This sample will be used for studying the chemical and dynamical evolution of the early galactic phase. Also, identifying stars with kinematical similarities would enable us to trace the galactic assembly.
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We report a comprehensive Chemo-dynamical analysis of LAMOST J1109+0754, a relatively bright (V = 12.8), extremely metal-poor ([Fe/H] = $-3.17$), and prograde ($J_\phi$ and $V_\phi$ $> 0$) star, with a strong \textit{r}-process... more
We report a comprehensive Chemo-dynamical analysis of LAMOST J1109+0754, a relatively bright (V = 12.8), extremely metal-poor ([Fe/H] = $-3.17$), and prograde ($J_\phi$ and $V_\phi$ $> 0$) star, with a strong \textit{r}-process enhancement ([Eu/Fe] = $+$0.94 $\pm$ 0.12, [Ba/Fe] = $-$0.52 $\pm$ 0.15). 31 chemical abundances (from Lithium to Thorium) were derived. We suggest a possible progenitor with stellar mass of 13.4-29.5 M$_\odot$. We argue that J1109+0754 is representative of the main \textit{r}-process component due to the well agreement with the scaled-solar \textit{r}-process component. We analyze the orbital history of this star in a {\it time-varying Galactic potential}, based on a Milky-Way analogue model extracted from \texttt{Illustris-TNG} simulations. Using this model, we carry out a statistical estimation of the phase-space coordinates of J1109+0754 at a young cosmic age. Collectively, the calculated motions, the derived chemistry, and the results from the cosmolo...
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Recent X-ray observations have revealed the complexity and diversity of high-mass X-ray binaries (HMXBs). This diversity challenges a classical understanding of the accretion process onto the compact objects. In this study, we reinforce... more
Recent X-ray observations have revealed the complexity and diversity of high-mass X-ray binaries (HMXBs). This diversity challenges a classical understanding of the accretion process onto the compact objects. In this study, we reinforce the conventional concept of the nature of wind-fed accretion onto a neutron star considering the geometrical effect of radiatively accelerated wind, and re-evaluate the transported angular momentum by using a simple wind model. Our results suggest that even in an OB-type HMXB fed by stellar wind, a large amount of angular momentum could be transported to form an accretion disk due to the wind-inhomogeneity, if the binary separation is tight enough and/or stellar wind is slow. We apply our model into actual systems such as LMC X-4 and OAO 1657-415, and discuss the possibility of disk formations in these systems.
Article history: The measured characteristics of binary pulsars provide valuable insights into the evolution of these systems. We study the aspects of binary evolution particularly relevant to binary Millisecond Pulsars (MSPs), and the... more
Article history: The measured characteristics of binary pulsars provide valuable insights into the evolution of these systems. We study the aspects of binary evolution particularly relevant to binary Millisecond Pulsars (MSPs), and the formation of close binaries involving degenerate stars through a spin-evolution diagram (spin-up line). For this task, we use a wide variety of binaries, including those with compact components that observed in different energy bands, which we analyze them according to the spin-up line. Their formation and evolution over timescales of binary evolution models are investigated in order to grab any constraint on their evolution, and to estimate the masses of neutron stars with different mass-transfer histories.
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Data release 2 (DR2) from the Gaia mission was of great help in precise determination of fundamental parameters of Close Visual Binary and Multiple Systems (CVBMSs), especially masses of their components, which are crucial parameters in... more
Data release 2 (DR2) from the Gaia mission was of great help in precise determination of fundamental parameters of Close Visual Binary and Multiple Systems (CVBMSs), especially masses of their components, which are crucial parameters in understanding formation and evolution of stars and galaxies. This article presents the complete set of fundamental parameters for two nearby close visual binary systems (CVBSs), which are HIP 19206 and HIP 84425. We utilised a combination of two methods; the first one is Tokovinin’s dynamical method to solve the orbit of the system and to estimate orbital elements and the dynamical mass sum, and the second one is Al-Wardat’s method for analysing CVBMSs to estimate the physical parameters of the individual components. The latest method employs grids of Kurucz line-blanketed plane parallel model atmospheres to build synthetic Spectral Energy Distributions (SEDs) of the individual components. Trigonometric parallax measurements given by Gaia DR2 and Hip...
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A White Dwarf (WD) star and a main-sequence companion may interact through their different stellar evolution stages. This sort of binary population has historically helped us improve our understanding of binary formation and evolution... more
A White Dwarf (WD) star and a main-sequence companion may interact through their different stellar evolution stages. This sort of binary population has historically helped us improve our understanding of binary formation and evolution scenarios. The data set used for the analysis consists of 115 well-measured WD masses obtained by the Sloan Digital Sky Survey (SDSS). A substantial fraction of these systems could potentially evolve and reach the Chandrasekhar limit, and then undergo an Accretion-Induced Collapse (AIC) to produce millisecond pulsars (MSPs). I focus my attention mainly on the massive WDs (M_WD > 1M_sun), that are able to grow further by mass-transfer phase in stellar binary systems to reach the Chandrasekhar mass. A mean value of M ~ 1.15 +/- 0.2M_sun is being derived. In the framework of the AIC process, such systems are considered to be good candidates for the production of MSPs. The implications of the results presented here to our understanding of binary MSPs ev...
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We have derived new physical quantities for several High-Mass X-ray Binaries (HMXBs) with supergiant (SG) companions through their cyclotron lines. The parameters are: the terminal velocity of the wind, the mass loss rate of the donor,... more
We have derived new physical quantities for several High-Mass X-ray Binaries (HMXBs) with supergiant (SG) companions through their cyclotron lines. The parameters are: the terminal velocity of the wind, the mass loss rate of the donor, the effective temperature and the magnetic fields. These parameters influence significantly the improvement of the model of accretion. In spite of the variety of their observational properties, the corresponding magnetic field is around B ~ 10^12 G. This result can be constrained by the effects on stellar evolution. In addition, we have performed a segmentation in the parameter space of donors intended for several SG-HMXB listed in our sample set. The parameter space can be categorized into five regimes depending on the possibility of disk formation associated with accretion from the stellar wind. This can give a quantitative clarification of the observed variability and the properties of these objects. We show that, when these systems come into the d...
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We have derived new physical quantities for several High-Mass X-ray Binaries(HMXBs) with supergiant (SG) companions through their cyclotron lines. The parameters are: the terminal velocity of the wind, the mass loss rate of the donor, the... more
We have derived new physical quantities for several High-Mass X-ray Binaries(HMXBs) with supergiant (SG) companions through their cyclotron lines. The parameters are: the terminal velocity of the wind, the mass loss rate of the donor, the effective temperature and the magnetic fields. These parameters influence significantly the improvement of the model of accretion. In spite of the variety of their observational properties, the corresponding magnetic field is around B∼1012G. This result can be constrained by the effects on stellar evolution. In addition, we have performed a segmentation in the parameter space of donors intended for several SG-HMXB listed in our sample set. The parameter space can be categorized into five regimes depending on the possibility of disk formation associated with accretion from the stellar wind.This can give a quantitative clarification of the observed variability and the properties of these objects. We show that, when these systems come into the direct accretion region, systems with corresponding parameters can emit X-rays
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We have derived new physical quantities for several High-Mass X-ray Binaries(HMXBs) with supergiant (SG) companions through their cyclotron lines. The parameters are: the terminal velocity of the wind, the mass loss rate of the donor, the... more
We have derived new physical quantities for several High-Mass X-ray Binaries(HMXBs) with supergiant (SG) companions through their cyclotron lines. The parameters are: the terminal velocity of the wind, the mass loss rate of the donor, the effective temperature and the magnetic fields. These parameters influence significantly the improvement of the model of accretion. In spite of the variety of their observational properties, the corresponding magnetic field is around B∼1012G. This result can be constrained by the effects on stellar evolution. In addition, we have performed a segmentation in the parameter space of donors intended for several SG-HMXB listed in our sample set. The parameter space can be categorized into five regimes depending on the possibility of disk formation associated with accretion from the stellar wind.This can give a quantitative clarification of the observed variability and the properties of these objects. We show that, when these systems come into the direct accretion region, systems with corresponding parameters can emit X-rays