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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 120 journals)
Showing 1 - 30 of 30 Journals sorted by number of followers
AIAA Journal     Hybrid Journal   (Followers: 1194)
SpaceNews     Free   (Followers: 826)
Journal of Spacecraft and Rockets     Hybrid Journal   (Followers: 773)
Journal of Propulsion and Power     Hybrid Journal   (Followers: 615)
Acta Astronautica     Hybrid Journal   (Followers: 495)
Advances in Space Research     Full-text available via subscription   (Followers: 458)
Aviation Week     Full-text available via subscription   (Followers: 437)
Aerospace Science and Technology     Hybrid Journal   (Followers: 428)
IEEE Transactions on Aerospace and Electronic Systems     Hybrid Journal   (Followers: 387)
Journal of Aircraft     Hybrid Journal   (Followers: 337)
Control Systems     Hybrid Journal   (Followers: 315)
Journal of Navigation     Hybrid Journal   (Followers: 281)
IEEE Aerospace and Electronic Systems Magazine     Full-text available via subscription   (Followers: 280)
Aircraft Engineering and Aerospace Technology     Hybrid Journal   (Followers: 264)
Gyroscopy and Navigation     Hybrid Journal   (Followers: 260)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 204)
Space Science International     Open Access   (Followers: 202)
Space Science Reviews     Hybrid Journal   (Followers: 97)
International Journal of Aerospace Engineering     Open Access   (Followers: 82)
Progress in Aerospace Sciences     Full-text available via subscription   (Followers: 81)
Advances in Aerospace Engineering     Open Access   (Followers: 70)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 69)
Propulsion and Power Research     Open Access   (Followers: 68)
Aerospace     Open Access   (Followers: 60)
Space Safety Magazine     Free   (Followers: 51)
Space Research Today     Full-text available via subscription   (Followers: 48)
Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering     Hybrid Journal   (Followers: 46)
International Journal of Aeroacoustics     Hybrid Journal   (Followers: 41)
IEEE Transactions on Circuits and Systems I: Regular Papers     Hybrid Journal   (Followers: 39)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 37)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 34)
Canadian Aeronautics and Space Journal     Full-text available via subscription   (Followers: 34)
International Journal of Aerospace Sciences     Open Access   (Followers: 32)
Journal of Aeronautics & Aerospace Engineering     Open Access   (Followers: 31)
CEAS Aeronautical Journal     Hybrid Journal   (Followers: 30)
Space Policy     Hybrid Journal   (Followers: 29)
Journal of Space Weather and Space Climate     Open Access   (Followers: 27)
Aviation Psychology and Applied Human Factors     Hybrid Journal   (Followers: 27)
Russian Aeronautics (Iz VUZ)     Hybrid Journal   (Followers: 24)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 24)
International Journal of Aerospace Psychology     Hybrid Journal   (Followers: 23)
Artificial Satellites     Open Access   (Followers: 23)
Annual of Navigation     Open Access   (Followers: 22)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 22)
Chinese Journal of Aeronautics     Open Access   (Followers: 21)
Nonlinear Dynamics     Hybrid Journal   (Followers: 20)
Aerospace Medicine and Human Performance     Full-text available via subscription   (Followers: 19)
Journal of Aerodynamics     Open Access   (Followers: 18)
Journal of Aerospace Engineering & Technology     Full-text available via subscription   (Followers: 18)
Aerospace Scientific Journal     Open Access   (Followers: 18)
Journal of Wind Engineering and Industrial Aerodynamics     Hybrid Journal   (Followers: 17)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 17)
International Journal of Space Structures     Full-text available via subscription   (Followers: 17)
Aviation     Open Access   (Followers: 17)
Proceedings of the Human Factors and Ergonomics Society Annual Meeting     Hybrid Journal   (Followers: 16)
Fatigue of Aircraft Structures     Open Access   (Followers: 15)
Aeronautical Journal, The     Hybrid Journal   (Followers: 13)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 13)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 12)
Journal of Airline and Airport Management     Open Access   (Followers: 12)
Elsevier Astrodynamics Series     Full-text available via subscription   (Followers: 12)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 12)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 11)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 11)
Journal of Aviation Technology and Engineering     Open Access   (Followers: 11)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 11)
Air Force Magazine     Full-text available via subscription   (Followers: 10)
International Journal of Space Technology Management and Innovation     Full-text available via subscription   (Followers: 10)
Aviation in Focus - Journal of Aeronautical Sciences     Open Access   (Followers: 10)
Journal of Aeronautical Materials     Open Access   (Followers: 9)
International Journal of Aviation Management     Hybrid Journal   (Followers: 9)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 9)
Journal of the Astronautical Sciences     Hybrid Journal   (Followers: 9)
Journal of Aircraft and Spacecraft Technology     Open Access   (Followers: 9)
Population Space and Place     Hybrid Journal   (Followers: 9)
Advances in Aerospace Science and Technology     Open Access   (Followers: 8)
Air Medical Journal     Hybrid Journal   (Followers: 8)
Journal of Space Safety Engineering     Hybrid Journal   (Followers: 8)
Journal of the American Helicopter Society     Full-text available via subscription   (Followers: 8)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 7)
Journal of Aerospace Technology and Management     Open Access   (Followers: 7)
International Journal of Aviation Technology, Engineering and Management     Full-text available via subscription   (Followers: 7)
Aerospace Systems     Hybrid Journal   (Followers: 6)
RocketSTEM     Free   (Followers: 6)
New Space     Hybrid Journal   (Followers: 6)
International Journal of Turbo and Jet-Engines     Hybrid Journal   (Followers: 6)
International Journal of Aviation, Aeronautics, and Aerospace     Open Access   (Followers: 5)
Civil Aviation High Technologies     Open Access   (Followers: 5)
Aviation Advances & Maintenance     Open Access   (Followers: 5)
REACH - Reviews in Human Space Exploration     Full-text available via subscription   (Followers: 5)
Cosmic Research     Hybrid Journal   (Followers: 5)
Unmanned Systems     Hybrid Journal   (Followers: 5)
International Journal of Sustainable Aviation     Hybrid Journal   (Followers: 5)
Aerotecnica Missili & Spazio : Journal of Aerospace Science, Technologies & Systems     Hybrid Journal   (Followers: 4)
Life Sciences in Space Research     Hybrid Journal   (Followers: 4)
Astrodynamics     Hybrid Journal   (Followers: 4)
Space and Polity     Hybrid Journal   (Followers: 4)
Investigación Pecuaria     Open Access   (Followers: 3)
Aerospace technic and technology     Open Access   (Followers: 3)
Journal of Astrobiology & Outreach     Open Access   (Followers: 3)
Journal of KONBiN     Open Access   (Followers: 3)
ASTRA Proceedings     Open Access   (Followers: 3)
Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering     Open Access   (Followers: 3)
npj Microgravity     Open Access   (Followers: 3)
Journal of Spatial Science     Hybrid Journal   (Followers: 3)
Вісник Національного Авіаційного Університету     Open Access   (Followers: 2)
Journal of Aviation/Aerospace Education & Research     Open Access   (Followers: 2)
Microgravity Science and Technology     Hybrid Journal   (Followers: 2)
MAD - Magazine of Aviation Development     Open Access   (Followers: 2)
Ciencia y Poder Aéreo     Open Access   (Followers: 2)
IEEE Journal on Miniaturization for Air and Space Systems     Hybrid Journal   (Followers: 2)
International Journal of Aeronautical and Space Sciences     Hybrid Journal   (Followers: 2)
Mekanika : Jurnal Teknik Mesin i     Open Access   (Followers: 1)
Technical Soaring     Full-text available via subscription   (Followers: 1)
Journal of the Australasian Society of Aerospace Medicine     Open Access   (Followers: 1)
Advances in Astronautics Science and Technology     Hybrid Journal   (Followers: 1)
Journal of Engineering and Technological Sciences     Open Access   (Followers: 1)
Transport and Aerospace Engineering     Open Access   (Followers: 1)
Open Aerospace Engineering Journal     Open Access   (Followers: 1)
Spatial Information Research     Hybrid Journal   (Followers: 1)
Science and Education : Scientific Publication of BMSTU     Open Access   (Followers: 1)
Gravitational and Space Research     Open Access  
Perspectives of Earth and Space Scientists i     Open Access  

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Journal Cover
Frontiers in Astronomy and Space Sciences
Number of Followers: 12  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2296-987X
Published by Frontiers Media Homepage  [86 journals]
  • Ionosphere Influenced From Lower-Lying Atmospheric Regions

    • Authors: Petra Koucká Knížová, Jan Laštovička, Daniel Kouba, Zbyšek Mošna, Katerina Podolská, Katerina Potužníková, Tereza Šindelářová, Jaroslav Chum, Jan Rusz
      Abstract: The ionosphere represents part of the upper atmosphere. Its variability is observed on a wide-scale temporal range from minutes, or even shorter, up to scales of the solar cycle and secular variations of solar energy input. Ionosphere behavior is predominantly determined by solar and geomagnetic forcing. However, the lower-lying atmospheric regions can contribute significantly to the resulting energy budget. The energy transfer between distant atmospheric parts happens due to atmospheric waves that propagate from their source region up to ionospheric heights. Experimental observations show the importance of the involvement of the lower atmosphere in ionospheric variability studies in order to accurately capture small-scale features of the upper atmosphere. In the Part I Coupling, we provide a brief overview of the influence of the lower atmosphere on the ionosphere and summarize the current knowledge. In the Part II Coupling Evidences Within Ionospheric Plasma—Experiments in Midlatitudes, we demonstrate experimental evidence from mid-latitudes, particularly those based on observations by instruments operated by the Institute of Atmospheric Physics, Czech Academy of Sciences. The focus will mainly be on coupling by atmospheric waves.
      PubDate: 2021-05-07T00:00:00Z
  • A Constrained Analysis of the 40Ca(18O,18F)40K Direct Charge Exchange
           Reaction Mechanism at 275 MeV

    • Authors: Manuela Cavallaro, Jessica I. Bellone, Salvatore Calabrese, Clementina Agodi, Stefano Burrello, Francesco Cappuzzello, Diana Carbone, Maria Colonna, N. Deshmukh, H. Lenske, A. Spatafora, L. Acosta, P. Amador-Valenzuela, T. Borello-Lewin, G. A. Brischetto, D. Calvo, V. Capirossi, E. Chávez, I. Ciraldo, M. Cutuli, F. Delaunay, H. Djapo, C. Eke, P. Finocchiaro, S. Firat, M. Fisichella, A. Foti, M. A. Guazzelli, A. Hacisalihoglu, F. Iazzi, L. La Fauci, R. Linares, J. Lubian, N. H. Medina, M. Moralles, J. R. B. Oliveira, A. Pakou, Luciano Pandola, H. Petrascu, F. Pinna, G. Russo, O. Sgouros, S. O. Solakci, V. Soukeras, G. Souliotis, D. Torresi, Salvatore Tudisco, A. Yildirin, V. A. B. Zagatto
      Abstract: The 40Ca(18O,18F)40K single charge exchange (SCE) reaction is explored at an incident energy of 275 MeV and analyzed consistently by collecting the elastic scattering and inelastic scattering data under the same experimental conditions. Full quantum-mechanical SCE calculations of the direct mechanism are performed by including microscopic nuclear structure inputs and adopting either a bare optical potential or a coupled channel equivalent polarization potential (CCEP) constrained by the elastic and inelastic data. The direct SCE mechanism describes the magnitude and shape of the angular distributions rather well, thus suggesting the suppression of sequential multi-nucleon transfer processes.
      PubDate: 2021-05-07T00:00:00Z
  • Catalytic Role of Refractory Interstellar Grain Analogs on H2 Formation

    • Authors: Tushar Suhasaria, Vito Mennella
      Abstract: Refractory dust grains have an important role to play in the chemistry of star and planet-forming regions. Their surfaces interact with interstellar gas and act as a catalyst for the formation of simple and complex molecules in space. Several mechanisms have been invoked to explain how molecular hydrogen is formed in reactions on dust grain surfaces in different regions of space. In this article, we give an overview of our understanding of the laboratory experiments, conducted over the last 20 years, that deal with H2 formation on interstellar grain analogs in space simulated conditions.
      PubDate: 2021-05-07T00:00:00Z
  • The Vertical and Adiabatic Ionization Energies of Silicon Carbide
           Clusters, (SiC)n, With n = 1–12

    • Authors: David Gobrecht
      PubDate: 2021-05-07T00:00:00Z
  • Improving Predictions of the 3D Dynamic Model of the Plasmasphere

    • Authors: Viviane Pierrard, Edith Botek, Fabien Darrouzet
      Abstract: In this perspective paper, we review and discuss different ways that can be used to improve the predictions of the models of the plasmaspheric region. The density of the background cold plasma and the plasmapause position are very important to determine the formation and propagation of waves and interactions with the other regions of the magnetosphere. Improvement of predictions includes refinement of the forecast of the geomagnetic indices that influence the density and the temperature of the particles in some models. Progress is also necessary for the understanding of the physical processes that affect the position of the plasmapause and its thickness since this boundary is not always very sharp, especially during low geomagnetic activity. These processes include the refilling after geomagnetic storms and substorms, the links with the ionosphere, and the expanding plasmaspheric wind during prolonged quiet periods. Using observations from in situ satellites like Van Allen Probes (EMFISIS and HOPE instruments), empirical relations can be determined to improve the dependence of the density and the temperature as a function of the radial distance, the latitude, and the magnetic local time, inside and outside the plasmasphere. This will be the first step for the improvement of our 3D dynamic SWIFF plasmaspheric model (SPM).
      PubDate: 2021-05-07T00:00:00Z
  • Plasma Dynamics in Low-Electron-Beta Environments

    • Authors: Stanislav Boldyrev, Nuno F. Loureiro, Vadim Roytershteyn
      Abstract: Recent in situ measurements by the MMS and Parker Solar Probe missions bring interest to small-scale plasma dynamics (waves, turbulence, magnetic reconnection) in regions where the electron thermal energy is smaller than the magnetic one. Examples of such regions are the Earth’s magnetosheath and the vicinity of the solar corona, and they are also encountered in other astrophysical systems. In this brief review, we consider simple physical models describing plasma dynamics in such low-electron-beta regimes, discuss their conservation laws and their limits of applicability.
      PubDate: 2021-05-05T00:00:00Z
  • Thionitroxyl Radical (H2NS) Isomers: Structures, Vibrational Spectroscopy,
           Electronic States and Photochemistry

    • Authors: Mahmoud Jarraya, Saida Ben Yaghlane, Raimund Feifel, Roberto Linguerri, Majdi Hochlaf
      Abstract: The thionitroxyl radical (H2NS) isomers are characterized using advanced ab initio methodologies. Computations are done using standard and explicitly correlated coupled cluster, CASSCF and MRCI approaches in conjunction with large basis sets, extrapolated to the complete basis set (CBS) limit. The lowest electronic states of different isomers are mapped along the stretching coordinates, thereby confirming the existence of the four already known ground state structures, namely H2NS, H2SN, cis-HNSH and trans-HNSH. Also, it is shown that only the lowest electronic excited states are stable, whereas the upper electronic states may undergo unimolecular decomposition processes forming H + HNS/HSN or the HN + SH or N + H2S or S + NH2 fragments. These data allow an assignment of the deep blue glow observed after reactions between “active nitrogen” and H2S at the beginning of the XXth century. For stable species, a set of accurate structural and spectroscopic parameters are provided. Since small nitrogen-sulfur molecular species are of astrophysical relevance, this work may help for identifying the thionitroxyl radical isomers in astrophysical media and in the laboratory.
      PubDate: 2021-05-04T00:00:00Z
  • The Distribution of Open Clusters in the Galaxy

    • Authors: Hektor Monteiro, Douglas A. Barros, Wilton S. Dias, Jacques R. D. Lépine
      Abstract: In this work we explore the new catalog of galactic open clusters that became available recently, containing 1,750 clusters that have been re-analyzed using the Gaia DR2 catalog to determine the stellar memberships. We used the young open clusters as tracers of spiral arms and determined the spiral pattern rotation speed of the Galaxy and the corotation radius, the strongest Galactic resonance. The sample of open clusters used here is increased by dozens of objects with respect to our previous works. In addition, the distances and ages values are better determined, using improvements to isochrone fitting and including an updated extinction polynomial for the Gaia DR2 photometric band-passes, and the Galactic abundance gradient as a prior for metallicity. In addition to the better age determinations, the catalog contains better positions in the Galactic plane and better proper motions. This allow us to discuss not only the present space distribution of the clusters, but also the space distribution of the clusters's birthplaces, obtained by integration of the orbits for a time equal to their age. The value of the rotation velocity of the arms (28.5 ± 1.0 km s−1 kpc−1) implies that the corotation radius (Rc) is close to the solar Galactic orbit (Rc/R0 = 1.01±0.08), which is supported by other observational evidence discussed in this text. A simulation is presented, illustrating the motion of the clusters in the reference frame of corotation. We also present general statistics of the catalog of clusters, like spatial distribution, distribution relative to height from the Galactic plane, and distribution of ages and metallicity. An important feature of the space distribution, the corotation gap in the gas distribution and its consequences for the young clusters, is discussed.
      PubDate: 2021-05-04T00:00:00Z
  • Spectra Recognition Model for O-type Stars Based on Data Augmentation

    • Authors: Wen-Yu Yang, Ke-Fei Wu, A-Li Luo, Zhi-Qiang Zou
      Abstract: It is an ongoing issue in astronomy to recognize and classify O-type spectra comprehensively. The neural network is a popular recognition model based on data. The number of O-stars collected in LAMOST is
      PubDate: 2021-05-03T00:00:00Z
  • Editorial: Gravitational Waves: A New Window to the Universe

    • Authors: Rosalba Perna, Bruno Giacomazzo
      PubDate: 2021-04-30T00:00:00Z
  • KORTES Mission for Solar Activity Monitoring Onboard International Space

    • Authors: Alexey Kirichenko, Sergey Kuzin, Sergey Shestov, Artem Ulyanov, Andrey Pertsov, Sergey Bogachev, Anton Reva, Ivan Loboda, Eugene Vishnyakov, Sergey Dyatkov, Nataliya Erkhova, Marek Stȩślicki, Janusz Sylwester, Stefan Płocieniak, Piotr Podgórski, Mirosław Kowaliński, Jarosław Bakała, Żaneta Szaforz, Marek Siarkowski, Daniel Ścisłowski, Tomasz Mrozek, Barbara Sylwester, Ilya Malyshev, Alexey Pestov, Vladimir Polkovnikov, Mikhail Toropov, Nikolay Salashchenko, Nikolay Tsybin, Nikolay Chkhalo
      Abstract: We present a description of the recent advances in the development of the KORTES assembly—the first solar oriented mission designed for the Russian segment of the International Space Station. KORTES consists of several imaging and spectroscopic instruments collectively covering a wide spectral range extending from extreme ultraviolet (EUV) wavelengths to X-rays. The EUV telescopes inside KORTES will trace the origin and dynamics of various solar phenomena, e.g., flares, CMEs, eruptions etc. EUV spectra provided by grazing-incidence spectroheliographs will enable precise DEM-diagnostics during these events. The monochromatic X-ray imager will observe the formation of hot plasma in active regions and outside them. The SolpeX module inside KORTES will offer an opportunity to measure fluxes, Doppler shifts and polarization of soft X-ray emission both in lines and continuum. SolpeX observations will contribute to studies of particle beams and chromospheric evaporation. The instrumentation of KORTES will employ a variety of novel multilayer and crystal optics. The deployment of KORTES is planned for 2024.
      PubDate: 2021-04-30T00:00:00Z
  • Interaction of HCO+ Cations With Interstellar Negative Grains. Quantum
           Chemical Investigation and Astrophysical Implications

    • Authors: Albert Rimola, Cecilia Ceccarelli, Nadia Balucani, Piero Ugliengo
      Abstract: In cold galactic molecular clouds, dust grains are coated by icy mantles and are prevalently charged negatively, because of the capture of the electrons in the gas. The interaction of the charged grains with gaseous cations is known to neutralize them. In this work, we focus on the chemical consequences of the neutralization process of HCO+, often the most abundant cation in molecular clouds. More specifically, by means of electronic structure calculations, we have characterized the energy and the structure of all possible product species once the HCO+ ion adsorbs on water clusters holding an extra electron. Two processes are possible: (i) electron transfer from the negative water cluster to the HCO+ ion or (ii) a proton transfer from HCO+ to the negative water cluster. Energetic considerations favor electron transfer. Assuming this scenario, two limiting cases have been considered in astrochemical models: (a) all the neutralized HCO+ is retained as neutral HCO adsorbed on the ice and (b) all the neutralized HCO+ gets desorbed to the gas phase as HCO. None of the two limiting cases appreciably contribute to the HCO abundance on the grain surfaces or in the gas.
      PubDate: 2021-04-29T00:00:00Z
  • Asteroseismic Observations of Hot Subdwarfs

    • Authors: A. E. Lynas-Gray
      Abstract: There are a number of reasons for studying hot subdwarf pulsation; the most obvious being that these stars remain a poorly understood late-stage of stellar evolution and knowledge of their interior structure, which pulsation studies reveal, constrains evolution models. Of particular interest are the red giant progenitors as in looking at a hot subdwarf we are seeing a stripped-down red giant as it would have been just before the Helium Flash. Moreover, hot subdwarfs may have formed through the merger of two helium white dwarfs and their study gives insight into how such a merger may have happened. A less obvious reason for studying pulsation in hot subdwarfs is that they provide a critical test of stellar envelope opacities and the atomic physics upon which they depend.
      PubDate: 2021-04-22T00:00:00Z
  • Shock Propagation and Associated Particle Acceleration in the Presence of
           Ambient Solar-Wind Turbulence

    • Authors: Fan Guo, Joe Giacalone, Lulu Zhao
      Abstract: The topic of this review paper is on the influence of solar wind turbulence on shock propagation and its consequence on the acceleration and transport of energetic particles at shocks. As the interplanetary shocks sweep through the turbulent solar wind, the shock surfaces fluctuate and ripple in a range of different scales. We discuss particle acceleration at rippled shocks in the presence of ambient solar-wind turbulence. This strongly affects particle acceleration and transport of energetic particles (both ions and electrons) at shock fronts. In particular, we point out that the effects of upstream turbulence is critical for understanding the variability of energetic particles at shocks. Moreover, the presence of pre-existing upstream turbulence significantly enhances the trapping near the shock of low-energy charged particles, including those near the thermal energy of the incident plasma, even when the shock propagates normal to the average magnetic field. Pre-existing turbulence, always present in space plasmas, provides a means for the efficient acceleration of low-energy particles and overcoming the well known injection problem at shocks.
      PubDate: 2021-04-22T00:00:00Z
  • A Multifluid Perspective on Multimessenger Modeling

    • Authors: Nils Andersson
      Abstract: This brief review introduces the notion of a relativistic multifluid system—a multi-component system with identifiable relative flows—and outlines a set of models for scenarios relevant for different astronomical observation channels. The specific problems used to illustrate the key principles include superfluid hydrodynamics (with relevance for radio and x-ray pulsar timing and gravitational-wave searches), heat flow (connecting to the problem of neutron star cooling and associated x-ray observations) and the coupling between matter and electromagnetism (linking to explosive phenomena like gamma-ray bursts and more subtle issues like the long-term evolution of a neutron star's magnetic field). We also comment on the coupling between matter and radiation, for which the multifluid approach would seem less appropriate. The main motivation of the survey is to illustrate less familiar aspects that come into play in multifluid problems, establish the relevant “language” and provide a platform for more detailed work on these issues.
      PubDate: 2021-04-22T00:00:00Z
  • Global Magnetohydrodynamic Simulations: Performance Quantification of
           Magnetopause Distances and Convection Potential Predictions

    • Authors: Agnit Mukhopadhyay, Xianzhe Jia, Daniel T. Welling, Michael W. Liemohn
      Abstract: The performance of three global magnetohydrodynamic (MHD) models in estimating the Earth's magnetopause location and ionospheric cross polar cap potential (CPCP) have been presented. Using the Community Coordinated Modeling Center's Run-on-Request system and extensive database on results of various magnetospheric scenarios simulated for a variety of solar weather patterns, the aforementioned model predictions have been compared with magnetopause standoff distance estimations obtained from six empirical models, and with cross polar cap potential estimations obtained from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) Model and the Super Dual Auroral Radar Network (SuperDARN) observations. We have considered a range of events spanning different space weather activity to analyze the performance of these models. Using a fit performance metric analysis for each event, the models' reproducibility of magnetopause standoff distances and CPCP against empirically-predicted observations were quantified, and salient features that govern the performance characteristics of the modeled magnetospheric and ionospheric quantities were identified. Results indicate mixed outcomes for different models during different events, with almost all models underperforming during the extreme-most events. The quantification also indicates a tendency to underpredict magnetopause distances in the absence of an inner magnetospheric model, and an inclination toward over predicting CPCP values under general conditions.
      PubDate: 2021-04-21T00:00:00Z
  • Formation of Interstellar Silicate Dust via Nanocluster Aggregation:
           Insights From Quantum Chemistry Simulations

    • Authors: Albert Rimola, Stefan T. Bromley
      Abstract: The issue of formation of dust grains in the interstellar medium is still a matter of debate. One of the most developed proposals suggests that atomic and heteromolecular seeds bind together to initiate a nucleation process leading to the formation of nanostructures resembling very small grain components. In the case of silicates, nucleated systems can result in molecular nanoclusters with diameters ≤ 2 nm. A reasonable path to further increase the size of these proto-silicate nanoclusters is by mutual aggregation. The present work deals with modeling this proto-silicate nanocluster aggregation process by means of quantum chemical density functional theory calculations. We simulate nanocluster aggregation by progressively reducing the size of a periodic array of initially well-separated nanoclusters. The resulting aggregation leads to a set of silicate bulk structures with gradually increasing density which we analyze with respect to structure, energetics and spectroscopic properties. Our results indicate that aggregation is a highly energetically favorable process, in which the infrared spectra of the finally formed amorphous silicates match well with astronomical observations.
      PubDate: 2021-04-21T00:00:00Z
  • Massive Star Modeling and Nucleosynthesis

    • Authors: Sylvia Ekström
      Abstract: After a brief introduction to stellar modeling, the main lines of massive star evolution are reviewed, with a focus on the nuclear reactions from which the star gets the needed energy to counterbalance its gravity. The different burning phases are described, as well as the structural impact they have on the star. Some general effects on stellar evolution of uncertainties in the reaction rates are presented, with more precise examples taken from the uncertainties of the 12C(α, γ)16O reaction and the sensitivity of the s-process on many rates. The changes in the evolution of massive stars brought by low or zero metallicity are reviewed. The impact of convection, rotation, mass loss, and binarity on massive star evolution is reviewed, with a focus on the effect they have on the global nucleosynthetic products of the stars.
      PubDate: 2021-04-21T00:00:00Z
  • Binary Gravitational Perturbations and Their Influence on the Habitability
           of Circumstellar Planets

    • Authors: Elke Pilat-Lohinger, Ákos Bazsó
      Abstract: In order to assess the habitability of planets in binary star systems, not only astrophysical considerations regarding stellar and atmospheric conditions are needed, but orbital dynamics and the architecture of the system also play an important role. Due to the strong gravitational perturbations caused by the presence of the second star, the study of planetary orbits in double star systems requires special attention. In this context, we show the important role of the main gravitational perturbations (resonances) and review our recently developed methods which allow a quick determination of locations of secular resonances (SRs) in binary stars for circumstellar planetary motion where a giant planet has to move exterior to the habitable zone (HZ). These methods provide the basis for our online-tool ShaDoS which allows a quick check of circumstellar HZs regarding secular perturbations. It is important to know the locations of SRs since they can push a dynamically quiet HZ into a high-eccentricity state which will change the conditions for habitability significantly. Applications of SHaDoS to the wide binary star HD106515 AB and the tight system HD41004 AB reveal a quiet HZ for both systems. However, the study of these systems indicates only for the tight binary star a possible change of the HZ's dynamical state if the orbital parameters change due to new observational data.
      PubDate: 2021-04-20T00:00:00Z
  • Dynamics of the Spiral-Arm Corotation and Its Observable Footprints in the
           Solar Neighborhood

    • Authors: Douglas A. Barros, Angeles Pérez-Villegas, Tatiana A. Michtchenko, Jacques R. D. Lépine
      Abstract: This article discusses the effects of the spiral-arm corotation on the stellar dynamics in the Solar Neighborhood (SN). All our results presented here rely on: (1) observational evidence that the Sun lies near the corotation circle, where stars rotate with the same angular velocity as the spiral-arm pattern; the corotation circle establishes domains of the corotation resonance (CR) in the Galactic disk; (2) dynamical constraints that put the spiral-arm potential as the dominant perturbation in the SN, comparing with the effects of the central bar in the SN; (3) a long-lived nature of the spiral structure, promoting a state of dynamical relaxing and phase-mixing of the stellar orbits in response to the spiral perturbation. With an analytical model for the Galactic potential, composed of an axisymmetric background deduced from the observed rotation curve, and perturbed by a four-armed spiral pattern, numerical simulations of stellar orbits are performed to delineate the domains of regular and chaotic motions shaped by the resonances. Such studies show that stars can be trapped inside the stable zones of the spiral CR, and this orbital trapping mechanism could explain the dynamical origin of the Local arm of the Milky Way (MW). The spiral CR and the near high-order epicyclic resonances influence the velocity distribution in the SN, creating the observable structures such as moving groups and their radially extended counterpart known as diagonal ridges. The Sun and most of the SN stars evolve inside a stable zone of the spiral CR, never crossing the main spiral-arm structure, but oscillating in the region between the Sagittarius-Carina and Perseus arms. This orbital behavior of the Sun brings insights to our understanding of questions concerning the solar system evolution, the Earth environment changes, and the preservation of life on Earth.
      PubDate: 2021-04-20T00:00:00Z
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