International Journal of Astronomy and Astrophysics

Journal Information
ISSN / EISSN : 21614717 / 21614725
Current Publisher: Scientific Research Publishing, Inc, (10.4236)
Total articles ≅ 342
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Latest articles in this journal

Nagat Abd El Rahman Hussein, Abd El-Rahim Hassan Ahmed, Esraa Gamal Sayed
International Journal of Astronomy and Astrophysics, Volume 9, pp 115-132; doi:10.4236/ijaa.2019.92009

Abstract:This study aims to estimate the quantum Bogoliubov-Born-Green-Kirkwood-Yvon (BBGKY) hierarchy in curvilinear coordinates. We used the results to calculate the quantum binary and triplet distribution functions in curvilinear coordinates. The analytical form of the quantum distribution functions was obtained for dusty plasma in Saturn’s rings model. We use particles-in-cell (PIC) simulations to find a visualization of dusty three-component plasma phase space in curvilinear coordinates. Our results were compared with others.
Bruce Hoeneisen, Hoeneisen Bruce
International Journal of Astronomy and Astrophysics, Volume 9, pp 133-141; doi:10.4236/ijaa.2019.92010

Abstract:In Part II of this study of spiral galaxy rotation curves we apply corrections and estimate all identified systematic uncertainties. We arrive at a detailed, precise, and self-consistent picture of dark matter.
Shaheera A. Altalhi, Magdy Ibrahim El Saftawy
International Journal of Astronomy and Astrophysics, Volume 9, pp 217-230; doi:10.4236/ijaa.2019.93016

Abstract:The relative motion between multiple satellites is a developed technique with many applications. Formation-flying missions use the relative motion dynamics in their design. In this work, the motion in invariant relative orbits is considered under the effects of second-order zonal harmonics in an equatorial orbit. The Hamiltonian framework is used to formulate the problem. All the possible conditions of the invariant relative motion are obtained with different inclinations of the follower satellite orbits. These second-order conditions warrantee the drift rates keeping two, or more, neighboring orbits from drifting apart. The conditions have been modeled. All the possibilities of choosing mean elements of the leader satellite orbit and differences in momenta between leader and follower satellites’ orbits are presented.
Cynthia Sharon Lawrence​, Ram Krishan Sharma
International Journal of Astronomy and Astrophysics, Volume 9, pp 200-216; doi:10.4236/ijaa.2019.93015

Abstract:This paper deals with the re-entry predictions of the space objects from the low eccentric orbit. Any re-entering object re-enters the Earth’s atmosphere with a high orbital velocity. Due to the aerodynamic heating the object tends to break into multiple fragments which later pose a great risk hazard to the population. Here a satellite is considered as the space object for which the re-entry prediction is made. This prediction is made with a package where the trajectory path, the time of re-entry and the survival rate of the fragments is done. The prediction is done using DRAMA 2.0—ESA’s Debris Risk Assessment and Mitigation Analysis Tool suite, MATLAB and Numerical Prediction of Orbital Events software. The predicted re-entry time of OSIRIS 3U was found to be on 7th March 2019, 7:25 (UTC), whereas the actual re-entry time was on 7th March 2019, 7:03 (UTC). The trajectory path found was 51.5699 deg. (Lat), −86.5738 deg. (Long.) with an altitude of 168.643 km. But the actual trajectory was 51.76 deg. (Lat), −89.01deg. (Long.) with an altitude of 143.5 km.
Chuan Liu, Ya-Qiu Jin
International Journal of Astronomy and Astrophysics, Volume 9, pp 335-353; doi:10.4236/ijaa.2019.93024

Abstract:HF (high frequency) radar sounder technology has been developed for several missions of Mars surface/subsurface exploration. This paper presents a model of rough surface and stratified sub-surfaces to describe the multi-layer structure of Mars polar deposits. Based on numerical simulation of radar echoes from rough surface/stratified interfaces, an inversion approach is developed to obtain the parameters of Polar Layered Deposits, i.e. layers thickness and dielectric constants. As a validation example, the SHARAD radar sounder data of the Promethei Lingula of Mars South Polar region is adopted for parameters inversion. The result of stratification is also analyzed and compared with the optical photo of the deep cliff of Chasma Australe canyon. Dielectric inversions show that the deposit media are not uniform, and the dielectric constants of the Promethei Lingula surfaces are large, and become reduced around the depth of 20 m - 30 m, below where most of the deposits are nearly pure ice, except a few thin layers with a lot of dust.
Feyiso Sado
International Journal of Astronomy and Astrophysics, Volume 9, pp 247-264; doi:10.4236/ijaa.2019.93018

Abstract:The observed properties of Gamma-Ray Bursts such as rapid variability of X-ray light curve and large energies strongly signature the compact binary, disk accreting system. Our work particularly highlights the extremely rotating, disk accreting black holes as physical source of the flares variability and X-ray afterglow plateaus of GRBs. We investigate the compact binary mergers (neutron star - neutron star and neutron star onto black hole) and gravitational core collapse of super massive star, where in both cases hyper-accreting Kerr hole is formed. The core collapse in a powerful gravitational wave explained as a potential source for the radiated flux of hard X-rays spectrum. We described the evolution of rapidly rotating, accreting BH in general relativity and the relativistic accretion flow in resistive MHD for viscous radiation. We compute the structure of accretion disk, the accretion luminosity of the dynamical evolution of inner accretion disk and precisely determine their radiation spectra, and compare to observational data of X-ray satellites. Finally, we obtained the resulting disk radiation basically explained as the X-ray luminosity of the central source, such as LMC X-1 and GRO J1655-40. These results are interestingly consistent with observational data of galactic X-ray source binary systems such as X-ray luminosities of Cygnus X-1 and Seyfert galaxies (NGC 3783, NGC 4151, NGC 4486 (Messier 87)) which are powerful emitters in X-ray and gamma-ray wavebands of the observed X-ray variability with typical luminosity.
Lorenzo Zaninetti
International Journal of Astronomy and Astrophysics, Volume 9, pp 302-320; doi:10.4236/ijaa.2019.93022

Abstract:The conservation of the energy flux in turbulent jets that propagate in the interstellar medium (ISM) allows us to deduce the law of motion when an inverse power law decrease of density is considered. The back-reaction that is caused by the radiative losses for the trajectory is evaluated. The velocity dependence of the jet with time/space is applied to the jet of HH34, for which the astronomical data of velocity versus time/space are available. The introduction of precession and constant velocity for the central star allows us to build a curved trajectory for the superjet connected with HH34. The bow shock that is visible in the superjet is explained in the framework of the theory of the image in the case of an optically thin layer.
Lorenzo Zaninetti
International Journal of Astronomy and Astrophysics, Volume 9, pp 393-410; doi:10.4236/ijaa.2019.94027

Abstract:The gamma function is a good approximation to the luminosity function of astrophysical objects, and a truncated gamma distribution would permit a more rigorous analysis. This paper examines the generalized gamma distribution (GG) and then introduces the scale and the new double truncation. The magnitude version of the truncated GG distribution with scale is adopted in order to fit the luminosity function (LF) for galaxies or quasars. The new truncated GG LF is applied to the five bands of SDSS galaxies, to the 2dF QSO Redshift Survey in the range of redshifts between 0.3 and 0.5, and to the COSMOS QSOs in the range of redshifts between 3.7 and 4.7. The average absolute magnitude versus redshifts for SDSS galaxies and QSOs of 2dF was modeled adopting a redshift dependence for the lower and upper absolute magnitude of the new truncated GG LF.
Shirsh Lata Soni, Prithvi Raj Singh, Bharti Nigam, Radhe Syam Gupta, Pankaj Kumar Shrivastava
International Journal of Astronomy and Astrophysics, Volume 9, pp 191-199; doi:10.4236/ijaa.2019.93014

Abstract:A Coronal Mass Ejection (CME) is an ejection of energetic plasma with magnetic field from the Sun. In traversing the Sun-Earth distance, the kinematics of the CME is immensely important for the prediction of space weather. The objective of the present work is to study the propagation properties of six major geo-effective CMEs and their associated interplanetary shocks which were observed during solar cycle 24. These reported CME events produced intense geo-magnetic storms (Dst > 140 nT). The six CME events have a broad range of initial linear speeds ~600 - 2700 km/sec in the LASCO/SOHO field of view, comparing two slow CMEs (speed ~579 km/sec and 719 km/sec), three moderate speed CMEs (speed ~1366, 1571, 1008 km/sec), and one fast CME (speed ~2684 km/sec). The actual arrival time of the reported events is compared with the arrival time calculated using the Empirical Shock Arrival model (ESA model). For acceleration estimation, we utilize three different acceleration-speed equations reported in the previous literatures for different acceleration cessation distance (ACD). In addition, we compared the transit time estimated using the second-order speed of CMEs with observed transit time. We also compared the observed transit time with transit time obtained from various shock arrival model. From our present study, we found the importance of acceleration cessation distance for CME propagation in interplanetary space and better acceleration speed for transit time calculation than other equations for CME forecasting.
Hinako Akimoto, Yoichi Itoh
International Journal of Astronomy and Astrophysics, Volume 9, pp 321-334; doi:10.4236/ijaa.2019.93023

Abstract:We report the results of optical spectroscopic monitoring observations of a T Tauri star, V409 Tau. A previous photometric study indicated that this star experienced dimming events due to the obscuration of light from the central star with a distorted circumstellar disk. We conducted medium-resolution (R ~10,000) spectroscopic observations with 2-m Nayuta telescope at Nishi-Harima Astronomical Observatory. Spectra were obtained in 18 nights between November 2015 and March 2016. Several absorption lines such as Ca I and Li, and the Hα emission line were confirmed in the spectra. The Ic-band magnitudes of V409 Tau changed by approximately 1 magnitude during the observation epoch. The equivalent widths of the five absorption lines are roughly constant despite changes in the Ic-band magnitudes. We conclude that the light variation of the star is caused by the obscuration of light from the central star with a distorted circumstellar disk, based on the relationship between the equivalent widths of the absorption lines and the Ic-band magnitudes. The blue component of the Hα emission line was dominant during the observation epoch, and an inverse P Cygni profile was observed in eight of the spectra. The time-variable inverse P Cygni profile of the Hα emission line indicates unsteady mass accretion from the circumstellar disk to the central star.