Authors:Aylin Caliskan, Rana Muhammad Zulqarnain, Ertan Güdekli, Imran Siddique, Hijaz Ahmad, Sameh Askar Abstract: This paper explores new neutron star models based on spherically symmetric space–time. We take into account the gravitational effects of f(T,T) gravity, in which T is the torsion and T is the trace of the energy–momentum tensor. Field equations are evaluated by incorporating the off-diagonal tetrad. In this paper, we discuss the detailed properties of compact star candidates 4U1538–52, J0437–4,715, J0030 + 0451, and 4U1820–30, like energy density, pressure profiles, gradients, anisotropy, energy conditions, equation of state, speeds of sound, TOV equation, and compactification parameters. We discuss all these characteristics using the quadratic cosmological model of f(T,T) gravity. We use the well-famed junction equations to evaluate the unknown parameters. Our detailed and comprehensive graphical analysis ensures that the model containing the anisotropic nature of stellar structures is physically acceptable, regular, and stable. PubDate: 2023-09-27T00:00:00Z
Authors:M. Cécere, A. Costa, H. Cremades, G. Stenborg Abstract: It has been shown that the magnetic structures surrounding coronal mass ejection (CME) events play a crucial role in their development and evolution along the first few solar radii. In particular, active regions, coronal holes, pseudostreamers, and helmet streamers are among the main coronal structures involved in the deviation of the trajectory of CMEs from their radial direction. Therefore, comprehensive observational studies along with their theoretical interpretation, aided by numerical simulations of the early evolution of CMEs, are the key ingredients to help determine their 3D trajectory in the interplanetary medium to narrow down the error in the estimation of the time of arrival of geoeffective events. In this mini-review, we compile the last decade of theoretical, numerical, and observational research that has shed light on the causes influencing the early deflection of CMEs away from their otherwise radial trajectory. PubDate: 2023-09-27T00:00:00Z
Authors:Anthony A. Chan, Scot R. Elkington, William J. Longley, Suhail A. Aldhurais, Shah S. Alam, Jay M. Albert, Allison N. Jaynes, David M. Malaspina, Qianli Ma, Wen Li Abstract: In this paper we describe K2, a comprehensive simulation model of Earth’s radiation belts that includes a wide range of relevant physical processes. Global MHD simulations are combined with guiding-center test-particle methods to model interactions with ultra low-frequency (ULF) waves, substorm injections, convective transport, drift-shell splitting, drift-orbit bifurcations, and magnetopause shadowing, all in self-consistent MHD fields. Simulation of local acceleration and pitch-angle scattering due to cyclotron-scale interactions is incorporated by including stochastic differential equation (SDE) methods in the MHD-particle framework. The SDEs are driven by event-specific bounce-averaged energy and pitch-angle diffusion coefficients. We present simulations of electron phase-space densities during a simplified particle acceleration event based on the 17 March 2013 event observed by the Van Allen Probes, with a focus on demonstrating the capabilities of the K2 model. The relative wave-particle effects of global scale ULF waves and very-low frequency (VLF) whistler-mode chorus waves are compared, and we show that the primary acceleration appears to be from the latter. We also show that the enhancement with both ULF and VLF processes included exceeds that of VLF waves alone, indicating a synergistic combination of energization and transport processes may be important. PubDate: 2023-09-26T00:00:00Z
Authors:Hermine Landt Abstract: Recent models for the inner structure of active galactic nuclei (AGN) aim at connecting the outer region of the accretion disk with the broad-line region and dusty torus through a radiatively accelerated, dusty outflow. Such an outflow not only requires the outer disk to be dusty and thus predicts disk sizes beyond the self-gravity limit but requires the presence of nuclear dust with favorable properties. Here, we investigate a large sample of type 1 AGN by near-infrared (near-IR) cross-dispersed spectroscopy with the aim to constrain the astrochemistry, location, and geometry of the nuclear hot dust region. Assuming a thermal equilibrium for optically thin dust, we derive the luminosity-based dust radius for different grain properties using our measurement of the temperature. We combine our results with independent dust radius measurements from reverberation mapping and interferometry, and show that large dust grains that can provide the necessary opacity for the outflow are ubiquitous in AGN. Using our estimates of the dust covering factor, we investigate the dust geometry using the effects of the accretion disk anisotropy. A flared disk-like structure for the hot dust is favored. Finally, we discuss the implication of our results for the dust radius-luminosity plane. PubDate: 2023-09-25T00:00:00Z
Authors:Joel Doré, Sandra Ortega Ugalde Abstract: Humans are microbial, ecosystems and symbioses. The relationship that humans have with their microbiomes is an essential element to maintaining health and wellbeing. Recent changes in lifestyles may have fostered an alteration of this symbiosis, which is frequently associated with chronic disorders. Here, we will review the state of the art on the central role of human-microbes symbiosis in health and disease, highlighting the innovations expected from the emerging knowledge on host-microbes symbiosis, for diagnosis, preventive nutrition, and a medicine of the ‘microbial human’. Since microbiome science also impacts several sustainable development goals of the Planetary Boundaries Initiative, we will also explore how microbiome science could help to provide sustainability tools and strategies aligned with the life support systems sought by the Micro-Ecological Life Support Systems Alternative (MELiSSA) Project lead by the European Space Agency (ESA). PubDate: 2023-09-22T00:00:00Z
Authors:Vanessa Polito, Marianne Peterson, Lindsay Glesener, Paola Testa, Sijie Yu, Katharine K. Reeves, Xudong Sun, Jessie Duncan Abstract: In this work we analyze a small B-class flare that occurred on 29 April 2021 and was observed simultaneously by the Interface Region Imaging Spectrograph (IRIS) and the Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray instrument. The IRIS observations of the ribbon of the flare show peculiar spectral characteristics that are typical signatures of energy deposition by non-thermal electrons in the lower atmosphere. The presence of the non-thermal particles is also confirmed directly by fitting the NuSTAR spectral observations. We show that, by combining IRIS and NuSTAR multi-wavelength observations from the corona to the lower atmosphere with hydrodynamic simulations using the RADYN code, we can provide strict constraints on electron-beam heated flare models. This work presents the first NuSTAR, IRIS and RADYN joint analysis of a non-thermal microflare, and presents a self-consistent picture of the flare-accelerated electrons in the corona and the chromospheric response to those electrons. PubDate: 2023-09-21T00:00:00Z
Authors:Laurence Lemelle, Eléonore Mottin, Denis Le Tourneau, Sébastien Rouquette, Lucie Campagnolo, Cécile Thévenot, Alain Maillet, Sébastien Barde, Emmanuel Garre, Jérémie Teisseire, Caroline Fontelaye, Vincent Jousseaume, Catherine Pudda, Olivier Constantin, Pierre Marcoux, Guillaume Nonglaton, Christophe Place Abstract: Future long-duration human spaceflights require developments to limit biocontamination of surface habitats. The three MATISS (Microbial Aerosol Tethering on Innovative Surfaces in the International Space Station) campaigns exposed surface treatments over several months in the ISS. To this end, eight sample holders designed were mounted with lamella-bearing FDTS ((1H, 1H, 2H, 2H)-perfluorodecyltrichlorosilane), SiOCH, and parylene hydrophobic coatings, at two different locations, for several months, during three distinct periods from 2016 to 2020. Tile scanning optical microscopy (×3 and ×30 magnifications) detected several thousand particles, indicating a relatively clean environment (a few particles per mm2). In previous studies, exposure rates were analyzed for all the coarse and fine particles detected on the largest total area of the integrated FDTS area exposed in the ISS (several cm2). Here, the contamination rates observed for a smaller constant area unit (the 0.66-cm2 window area of the holder) were statistically analyzed. Therefore, a statistical difference in rate distributions between RGSH (Return Grid Sensor House) and EDR (European Drawer Rack) and between FDTS and either SiOCH or parylene was shown for the coarse particles but not for the fine particles. The contamination rates were found to be low, confirming the efficiency of the long-term air purification system. The rates tend to vary with the astronaut occupancy rates. Surfaces of spacecraft for long-duration exploration left unmanned during dormancy periods can be considered safe from biocontamination. PubDate: 2023-09-21T00:00:00Z
Authors:Thomas S. Sotirelis, Jesper W. Gjerloev, Marc Hairston Abstract: The protons and electrons on newly reconnected field lines exhibit time-of-flight effects that have been observed and modelled on both the dayside and nightside, at both high and low altitudes. These reconnection signatures feature proton energy distributions that are cutoff toward low energy. In LEO the cutoff energy exhibits a dispersion with latitude, typically seen in the cusp on the dayside, and referred to as velocity dispersed ion structures on the nightside. Here, an automated algorithm for detecting such low-energy cutoffs in the energy spectra of precipitating ions was developed, without regard for any possible dispersion with latitude. The occurrences of LEC ion spectra were mapped over a year of DMSP observations. There are four distinct components to this map, two of which are produced by reconnection. On the dayside LEC ion spectra are seen in cusp, mantle, and open-LLBL precipitation, predominantly at sub-keV energies, as the result of dayside reconnection. On the nightside LEC ion spectra are seen at the poleward edge of the oval at supra-keV energies (usually dispersed with latitude), that indicate magnetotail reconnection. There is another supra-keV population seen on the dusk side at the equatorward edge of the oval, possibly indicating the onset of isotropy. Finally, there is a sub-keV population seen throughout the auroral oval that is thought to consist of ions accelerated out of the opposing hemisphere. The presence of the nightside reconnection signature is modulated by magnetic activity level. Superposed epoch analyses of the ionospheric flow velocity reveal flow through the open–closed boundary when reconnection signatures are present, and enhanced upflow on the dayside when reconnection signatures are present. PubDate: 2023-09-20T00:00:00Z
Authors:Connor O’Brien, Brian M. Walsh, Ying Zou, Samira Tasnim, Huaming Zhang, David Gary Sibeck Abstract: Introduction: For the last several decades, continuous monitoring of the solar wind has been carried out by spacecraft at the first Earth-Sun Lagrange point (L1). Due to computational expense or model limitations, those data often must be propagated to some point closer to the Earth in order to be usable by those studying the interaction between Earth’s magnetosphere and the solar wind. The current most widely used tool to propagate measurements from L1 (roughly 235 RE upstream) to Earth is the planar propagation method, which includes a number of known limitations. Motivated by these limitations, this study introduces a new algorithm called the Probabilistic Regressor for Input to the Magnetosphere Estimation (PRIME).Methods: PRIME is based on a novel probabilistic recurrent neural network architecture, and is capable of incorporating solar wind time history from L1 monitors to generate predictions of near-Earth solar wind as well as estimate uncertainties for those predictions.Results: A statistical validation shows PRIME’s predictions better match MMS magnetic field and plasma measurements just upstream of the bow shock than measurements from Wind propagated to MMS with a minimum variance analysis-based planar propagation technique. PRIME’s continuous rank probability score (CRPS) is 0.214σ on average across all parameters, compared to the minimum variance algorithm’s CRPS of 0.350σ. PRIME’s performance improvement over minimum variance is dramatic in plasma parameters, with an improvement in CRPS from 2.155 cm−3 to 0.850 cm−3 in number density and 16.15 km/s to 9.226 km/s in flow velocity VX GSE.Discussion: Case studies of particularly difficult to predict or extreme conditions are presented to illustrate the benefits and limitations of PRIME. PRIME’s uncertainties are shown to provide reasonably reliable predictions of the probability of particular solar wind conditions occurring.Conclusion: PRIME offers a simple solution to common limitations of solar wind propagation algorithms by generating accurate predictions of the solar wind at Earth with physically meaningful uncertainties attached. PubDate: 2023-09-19T00:00:00Z
Authors:Yoshiaki Kitaya, Takashige Kawamoto, Ryosuke Endo, Toshio Shibuya Abstract: There is a need to develop production technology that effectively uses limited water and other resources to create a stable food supply in space. Aquaponics, which combine hydroponics and aquaculture, is expected to be an efficient system for producing crops and animal proteins. This system sustains the reuse of water and balances nutrient elements between both cultures using dissolved elements in fish excrement for plant growth. To evaluate the effect of fish density on biological production and nitrogen usage efficiency in aquaponics combining lettuce hydroponics and loach aquaculture, we investigated the growth performance of lettuce plants and loach fish. We focused on the balance of nutrient elements, especially nitrogen flow in the system. As a result, we found that lettuce grew in aquaponics with a half-strength standard solution with an optimal combination of the number of plants and fish as well as hydroponics with a standard solution. Increasing the density of loach fish and lettuce plants can increase the total biological production of fish and plants. However, it will be important to control both fish and plant densities to increase nitrogen recovery in aquaponics with a high fish density. PubDate: 2023-09-18T00:00:00Z
Authors:Federico Gasperini, Brian J. Harding, Geoffrey Crowley, Thomas J. Immel Abstract: Growing evidence indicates that a selected group of global-scale waves from the lower atmosphere constitute a significant source of ionosphere-thermosphere (IT, 100–600 km) variability. Due to the geometry of the magnetic field lines, this IT coupling occurs mainly at low latitudes ( PubDate: 2023-09-18T00:00:00Z
Authors:Purvi Udhwani, Arpit Kumar Shrivastav, Ritesh Patel Abstract: SiRGraF Integrated Tool for Coronal dynaMics (SITCoM) is based on the Simple Radial Gradient Filter used to filter the radial gradient in the white-light coronagraph images and bring out dynamic structures. SITCoM has been developed in Python and integrated with SunPy and can be installed by users with the command pip install sitcom. This enables the user to pass the white-light coronagraph data to the tool and generate radially filtered output with an option to save in various formats as required. We implemented the functionality of tracking the transients such as coronal mass ejections, outflows, and plasma blobs, using height–time plots and deriving their kinematics. In addition, SITCoM also supports oscillation and wave studies such as for streamer waves. This is performed by creating a distance–time plot at a user-defined location (artificial slice) and fitting a sinusoidal function to derive the properties of waves, such as time period, amplitude, and damping time (if any). We provide the option to manually or automatically select the data points to be used for fitting. SITCoM is a tool to analyze some properties of coronal dynamics quickly. We present an overview of the SITCoM with the applications for deriving coronal dynamics’ kinematics and oscillation properties. We discuss the limitations of this tool along with prospects for future improvement. PubDate: 2023-09-15T00:00:00Z
Authors:Martin Ferus, Antonín Knížek, Giuseppe Cassone, Paul B. Rimmer, Hitesh Changela, Elias Chatzitheodoridis, Inna Uwarova, Ján Žabka, Petr Kabáth, Franz Saija, Homa Saeidfirozeh, Libor Lenža, Miroslav Krůs, Lukáš Petera, Lukáš Nejdl, Petr Kubelík, Anna Křivková, David Černý, Martin Divoký, Michael Pisařík, Tomáš Kohout, Lakshika Palamakumbure, Barbora Drtinová, Klára Hlouchová, Nikola Schmidt, Zita Martins, Jorge Yáñez, Svatopoluk Civiš, Pavel Pořízka, Tomáš Mocek, Jona Petri, Sabine Klinkner Abstract: Meteor plasmas and impact events are complex, dynamic natural phenomena. Simulating these processes in the laboratory is, however, a challenge. The technique of laser induced dielectric breakdown was first used for this purpose almost 50 years ago. Since then, laser-based experiments have helped to simulate high energy processes in the Tunguska and Chicxulub impact events, heavy bombardment on the early Earth, prebiotic chemical evolution, space weathering of celestial bodies and meteor plasma. This review summarizes the current level of knowledge and outlines possible paths of future development. PubDate: 2023-09-15T00:00:00Z
Authors:Ivana Molina, Ludger Scherliess Abstract: Winds in the thermosphere play an important role in the transport of momentum and energy in the upper atmosphere and affect the composition, dynamics and morphology of the ionospheric plasma. Although the general morphology of the winds is well understood, we are only starting to understand its variability. During the last decade it has become inherently clear that in addition to solar forcing of the thermosphere, the lower atmosphere also is an important driver of thermospheric variability. Therefore, an understanding of thermospheric variability and its spatial and temporal correlations is critical for an improved understanding of the coupled ionosphere-thermosphere system and the coupling to the lower atmosphere. The Gravity Field and Steady-State Ocean Explorer (GOCE) provided zonal winds near dawn and dusk at an altitude of around 260 km from November 2009 to October 2013. We have used GOCE zonal wind observations from low- to mid-latitudes obtained during geomagnetically quiet times to investigate spatial and temporal correlations in the zonal winds near dawn and dusk. Latitudinal correlations were calculated for the GOCE zonal winds for December solstice separately for each year from 2009 to 2012 and their year-to-year variation was established. Correlations between hemispheric conjugate points were found at mid latitudes during the latter years. Latitudinal correlations for December solstice 2009 and June solstice 2010 were compared and the correlation length was found to be consistently larger in the winter hemisphere during dawn and in the summer hemisphere during dusk. Zonal wind longitudinal/temporal correlations were also determined for December 2009 and 2011 and for June 2010 and found to be periodic in longitude/time. The temporal evolution of the temporal/longitudinal correlations were found to gradually decrease over the course of several days. The maxima in the correlation coefficients were always located in the winter hemisphere during dawn and in the summer hemisphere during dusk. During dawn, the largest contributors to the temporal/longitudinal correlations were found to be nonmigrating tides, whereas during dusk, additional waves appear to play important roles. PubDate: 2023-09-14T00:00:00Z
Authors:L. A. Balona Abstract: High-precision photometry from TESS has revealed over 500 stars, located between the δ Scuti and β Cephei instability strips, which pulsate with high frequencies. Models do not predict high pulsation frequencies in these stars. These anomalous variables may be identified with the historical “Maia” variables. From the projected rotational velocities, it is shown that the rotation rates of Maia variables are no different from main sequence or SPB stars in the same effective temperature range. Some Maia stars pulsate at frequencies typical of roAp stars. It is shown that Maia stars should be considered an extension of δ Scuti variables to effective temperatures as high as 18,000 K, rather than as a separate class. The TESS data show a continuous sequence of low-frequency pulsating stars linking the γ Doradus and SPB variables, which is not predicted by the models. There are, in fact, no well-defined instability strips at all among upper main sequence stars, which means that arbitrary choices of effective temperature and frequency ranges need to be made in order to assign a particular variability class. It seems that a mixture of driving mechanisms is present in which convection may play a very important role. PubDate: 2023-09-14T00:00:00Z
Authors:T. M. Esman, J. R. Espley, J. R. Gruesbeck, A. Verbiscer, J. Giacalone, A. J. Halford Abstract: Schumann resonances are electromagnetic resonances generally associated with lightning. If they exist on Mars, Schumann resonances are expected to resonate within the ionospheric cavity at a fundamental frequency of 7–14 Hz. We conducted a search for 5–16 Hz signals below 400 km in magnetic field data from the Mars Global Surveyor (MGS) and Mars Atmosphere and Volatile Evolution (MAVEN) missions. Fast Fourier transforms and wavelet analysis were used to find these signals and investigate their characteristics further. We discuss our null results and the required steps forward to continue and improve this search. Future studies will require higher sensitivity instruments and would benefit from additional missions that reach into the lower ionosphere of Mars. PubDate: 2023-09-13T00:00:00Z
Authors:Tobias C. Hinse, Bertil F. Dorch, Lars V. T. Occhionero, Jakob P. Holck Abstract: The 450th anniversary of the discovery of the SN 1572 supernova event was celebrated in 2022. A closer look at the historical development of the field of supernova astronomy reveals the scientific importance of Tycho Brahe’s 1572 observations of this “new star.” In their quest to learn more about the new type of stellar explosion and subsequent evolution, the initial protagonists in this field (Baader and Zwicky among others) gradually turned their attention to the final remnant state of these supernova events. Since the remnant object thought to be associated with the extragalactic supernova event was found to be very dim, the focus quickly shifted toward nearby galactic events. It is at this point where Tycho Brahe’s observations played an important and often overlooked role in the context of the development of stellar evolution as a scientific field. Tycho Brahe’s meticulous and detailed recordings of the change in brightness of the new star not only allowed modern astronomers to classify SN 1572 as a supernova event but also helped them pinpoint the exact astrometric location of SN 1572. These findings helped to empirically link extragalactic supernova events to nearby past supernova remnants in the Milky Way. This enabled subsequent observations allowing further characterization. Transforming the historical recordings to a standardized photometric system also allowed the classification of SN 1572 as a type I supernova event. PubDate: 2023-09-12T00:00:00Z
Authors:Nitin Vashishtha, Satabdwa Majumdar, Ritesh Patel, Vaibhav Pant, Dipankar Banerjee Abstract: The kinematics of coronal mass ejections (CMEs) are crucial for understanding their initiation mechanism and predicting their impact on Earth and other planets. With most of the acceleration and deceleration occurring below 4 R⊙, capturing this phase is vital to better understand their initiation mechanism. Furthermore, the kinematics of CMEs in the inner corona ( PubDate: 2023-09-12T00:00:00Z
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