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  • Electromagnetic-launch-based method for cost-efficient space debris removal
    Open Astron. (IF 0.831) Pub Date : 2020-09-18
    Chongyuan Hou; Yuan Yang; Yikang Yang; Kaizhong Yang; Xiao Zhang; Junyong Lu

    The increase in space debris orbiting Earth is a critical problem for future space missions. Space debris removal has thus become an area of interest, and significant research progress is being made in this field. However, the exorbitant cost of space debris removal missions is a major concern for commercial space companies. We therefore propose the debris removal using electromagnetic launcher (DREL)

    更新日期:2020-09-21
  • Bianchi type–I Model with Time Varying Λ and G: The Generalized Solution
    Open Astron. (IF 0.831) Pub Date : 2020-09-11
    Alnadhief H. A. Alfedeel

    In this paper, we have investigated the homogeneous and anisotropic Bianchi type–I cosmological model with a time-varying Newtonian and cosmological constant. We have analytically solved Einstein’s field equations (EFEs) in the presence of a stiff-perfect fluid. We show that the analytical solution for the average scale factor for the generalized Friedman equation involves the hyper-geometric function

    更新日期:2020-09-15
  • Some kinematics of halo coronal mass ejections
    Open Astron. (IF 0.831) Pub Date : 2020-08-28
    Virendra Kumar Verma; Nishant Mittal; Ramesh Chandra

    We present an investigation of halo coronal mass ejections (HCMEs) kinematics and other facts about the HCMEs. The study of HCMEs is very important because HCMEs are regarded as the main causes of heliospheric and geomagnetic disturbances. In this study, we have investigated 313 HCMEs observed during 1996-2012 by LASCO, coronal holes, and solar flares. We find that HCMEs are of two types: accelerated

    更新日期:2020-08-31
  • New Data on the Eclipsing Binary V1848 Ori and Improved Orbital and Light Curve Solutions
    Open Astron. (IF 0.831) Pub Date : 2020-08-03
    Fatemeh Davoudi; Atila Poro; Fahri Alicavus; Afshin Halavati; Saeed Doostmohammadi; AmirAbbas Shahdadi; Sareh Vahedi; Arman Pishahang; Maryam Zare; Milad Jamali; AmirMohammad Salajeghe; Faezeh Jahediparizi; Hassan Ashta; Seyed Mohsen Shojaatalhosseini

    New observations of the eclipsing binary system V1848 Ori were carried out using the V filter resulting in a determination of new times of minima and new ephemeris were obtained. We presented the first complete analysis of the system’s orbital period behavior and analysis of O-C diagram done by the GA and MCMC approaches in OCFit code. The O-C diagram demonstrates a sinusoidal trend in the data; this

    更新日期:2020-08-06
  • The dynamical environment of the primary in the triple asteroid (45) Eugenia
    Open Astron. (IF 0.831) Pub Date : 2020-07-22
    Min Jiang; Qingtian Ma

    We investigated the dynamical behavior in the potential of the primary in the triple asteroid (45) Eugenia with the calculation of the full gravitational potential caused by its 3D irregular shape. We presented the whole structure of the gravitational potential and the effective potential of (45) Eugenia in the coordinate planes, and showed the surface height, surface gravitational force accelerations

    更新日期:2020-07-27
  • Two-dimensional correlation analysis of periodicity in active galactic nuclei time series
    Open Astron. (IF 0.831) Pub Date : 2020-07-22
    Andjelka B. Kovačević; Luka Č. Popović; Dragana Ilić

    The active galactic nuclei (AGN) are among the most powerful sources with an inherent, pronounced and random variation of brightness. The randomness of their time series is so subtle as to blur the border between aperiodic fluctuations and noisy oscillations. This poses challenges to analysing of such time series because neither visual inspection nor pre-exisitng methods can identify well oscillatory

    更新日期:2020-07-27
  • Does Hawking predict the correct temperature of a black-hole?
    Open Astron. (IF 0.831) Pub Date : 2020-07-13
    Kapil Chandra

    In our study of the validity of Hawking’s predicted radiation temperature of a black-hole, we found that the calculated temperature is another form of Zeldovich’s expression for the cosmological constant. We reasoned that as Zeldovich predicted the extreme value of cosmological constant thus Hawking might have also predicted an extreme temperature. However, the actual temperature might be something

    更新日期:2020-07-14
  • On the role of collisions with meteoroids in splitting and acceleration of heliocentric velocity of comets
    Open Astron. (IF 0.831) Pub Date : 2020-06-27
    Ayyub Guliyev; Rustam Guliyev

    The hypothesis on the role of the meteoroid impacts in the comet nuclei splitting as well as acceleration of their heliocentric velocity are considered. Inclinations of the orbits of split comets relative to the movement planes of 100 known meteoroid streams are calculated. The analysis is carried out for the cases: when the cometary nodes are located from the meteoroids orbit < 0.1 AU; MOID-values

    更新日期:2020-06-29
  • Planck Neutrinos as Ultra High Energy Cosmic Rays
    Open Astron. (IF 0.831) Pub Date : 2020-06-24
    Dmitri L. Khokhlov

    The studied conjecture is that ultra high energy cosmic rays (UHECRs) are hypothetical Planck neutrinos arising in the decay of the protons falling onto the gravastar. The proton is assumed to decay at the Planck scale into positron and four Planck neutrinos. The supermassive black holes inside active galactic nuclei, while interpreted as gravastars, are considered as UHECR sources. The scattering

    更新日期:2020-06-24
  • The temperature model of the thermal re-radiation model in multilayer insulation systems
    Open Astron. (IF 0.831) Pub Date : 2020-06-05
    Wenhui Cui; Zhenyu Sun; Jian Yang

    In this manuscript, the temperature model of multilayer insulation (MLI) on a spacecraft solar panel in thermal radiation is considered. The thermal insulation performance of MLI and the stress of the spacecraft are also considered. The thermal equilibrium equation of the surface temperature of MLI spacecraft in the presence of current transfer, and the iterative temperature acquisition algorithm of

    更新日期:2020-06-05
  • New evidence of the Suess/de Vries cycle existing in historical naked-eye observations of sunspots
    Open Astron. (IF 0.831) Pub Date : 2020-05-20
    Lihua Ma; José M. Vaquero

    Solar activity affects geophysical and heliophysical processes. Long-term changes in solar activity are closely related to climate change. Solar physicists and earth science researchers need longer observations of solar activity. Current continuous observations of solar activity are only about 400 years. Some scholars have compiled naked-eye observations of sunspots from 200 BC to 1918 AD from historical

    更新日期:2020-05-20
  • Asymmetry between galaxies with different spin patterns: A comparison between COSMOS, SDSS, and Pan-STARRS
    Open Astron. (IF 0.831) Pub Date : 2020-05-13
    Lior Shamir

    Previous observations of a large number of galaxies show differences between the photometry of spiral galaxies with clockwise spin patterns and spiral galaxies with counterclockwise spin patterns. In this study the mean magnitude of a large number of clockwise galaxies is compared to the mean magnitude of a large number of counterclockwise galaxies. The observed difference between clockwise and counterclockwise

    更新日期:2020-05-13
  • Broad spectral lines in AGNs and supermassive black hole mass measurements
    Open Astron. (IF 0.831) Pub Date : 2020-05-13
    Luka Č. Popović

    The mass measurement of supermassive black holes (SMBHs) is a very complex task. Between several methods for SMBH mass measurements, some of them use the spectral lines, which indicate the motion of the emitting/absorbing material around an SMBH. Mostly, there is an assumption of virialization of line emitting gas in the region which is close to the central SMBH. In this paper we will give an overview

    更新日期:2020-05-13
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