Celestial Bodies Research Articles

Theoretical Insights into Gas Migration Within Ice on Earth and Icy Celestial Bodies

Theoretical Insights into Gas Migration Within Ice on Earth and Icy Celestial Bodies

The Energy Dispersion of Magnetic Rossby Waves in the Quasi-geostrophic Shallow Water Magnetohydrodynamic Theory

Abstract This research firstly comprehensively investigates the energy dispersion of magnetic Rossby waves in zonally non-uniform basic state by applying the quasi-geostrophic (QG) shallow water magnetohydrodynamic (SWMHD) equations. The eddy momentum and heat flux transported by Magnetic Rossby waves, which can be described by the group velocity vector, have significant impacts on the large-scale dynamics of various celestial bodies. The findings suggest that the energy dispersion paths, also called rays, are curves and restricted in limited regions in the non-uniform basic states, in contrast with straight lines in the uniform basic states. Furthermore, the limited propagative regions are influenced by three important meridional locations, which are defined as the symmetric turning location, the asymmetric turning location, and the critical location. The first two reflect rays and the third one acts as an asymptote. The propagative region that is enclosed by a turning location and a critical location is more general. Besides, the occurrence of the asymmetric turning location, which is mainly depended on the distribution of the zonal basic flow, is a quite new feature of the energy dispersion for magnetic Rossby waves since there is no asymmetric turning location for Rossby waves on the Earth’s atmosphere and ocean. The results have important applications in illustrating interactions between magnetic Rossby waves and zonally basic states and in explaining the maintenance of the zonal flow and meridional circulation of various celestial bodies.

Radiation mechanism of twin kilohertz quasi-periodic oscillations in neutron star low-mass X-ray binaries

Context. The connection between quasi-periodic oscillations (QPOs) and magnetic fields has been investigated in various celestial bodies. Magnetohydrodynamic (MHD) waves have been employed to explain the simultaneous upper and lower kilohertz (kHz) QPOs. Nevertheless, the intricate and undefined formation pathways of twin kHz QPOs present a compelling avenue for exploration. This study area holds great interest as it provides an opportunity for deriving crucial parameters related to compact stars. Aims. We strive to develop a self-consistent model elucidating the radiation mechanism of twin kHz QPOs, which we then compare it with observations. Methods. A sample of 28 twin kHz QPOs detected from the X-ray binary 4U 1636–53 was used for a comparison with the results of the Markov chain Monte Carlo calculations based on our model of the radiation mechanism of twin kHz QPOs, which is related to twin MHD waves. Results. We obtained 28 groups of parameters of 4U 1636–53 and a tight exponential fit between the flux and the temperature of seed photons to Compton up-scattering and find that the electron temperature in the corona around the neutron star decreases with increasing seed photon temperature. Conclusions. The origin of twin kHz QPOs are dual disturbances that arise from twin MHD waves that are generated at the innermost radius of an accretion disc. The seed photons can be transported through a high temperature corona and are Compton up-scattered. The photons that vary the frequencies of twin MHD waves lead to the observed twin kHz QPOs.

CZ Aqr: An Oscillating Eclipsing Algol-type System Composed of a δ Sct Primary Star and a Subgiant Star in a Quadruple System

Eclipsing Algol-type systems containing a δ Scuti (hereafter δ Sct) star enable precise determination of physical parameters and the investigation of stellar internal structure and evolution. We present the absolute parameters of CZ Aquarius (hereafter CZ Aqr) based on TESS data. CZ Aqr has an orbital period of 0.86275209 day, a mass ratio of 0.489 (6), and the secondary component nearly fills its Roche lobe. O − C analysis reveals a downward parabolic trend and a cyclical variation with a period of 88.2 yr. The downward parabola suggests a long-term decrease in the orbital period with Ṗ = −3.09 × 10−8 days yr−1. The mass loss rate is estimated to be 4.54 × 10−9 M ⊙ yr−1, which is possibly due to magnetic stellar wind or a hot spot. The cyclical variation might be caused by the light travel time effect via the presence of a third body with a minimum mass of M3min = 0.312 (21) M ⊙. Additionally, there are two possible celestial bodies in a 2:7 resonance orbit around CZ Aqr. The asymmetric light curve is explained by adding a hot spot on the surface of the primary star. After removing the binary model, 26 frequencies were extracted from TESS data. Two radial modes were newly identified among three possible independent frequencies. Our results show that the eclipsing Algol-type system is composed of a δ Sct primary star and a subgiant star in a quadruple system.

Black holes - from relativity to Hawking radiation

Abstract. Black Hole (BH for short) is a kind of compact body in the universe predicted by the general theory of relativity. The gravitational pull of a black hole is extremely strong. A black hole is a celestial body whose curvature of space-time is so great that light cannot escape from its event horizon. There are four main ideas about how black holes form: collapsing stars, exploding supernovae, merging multiple black holes, and primordial black holes. In this article, we will start with Einstein's theory of relativity to analyze black holes, and focus on Schwarzschild black holes.

A Novel Ephemeris Model for Martian Moons Incorporating Their Free Rotation

High-precision ephemerides not only support space missions, but can also be used to study the origin and future of celestial bodies. In this paper, a coupled orbit-rotation dynamics model that fully takes into account the rotation of the Martian moons is developed. Phobos and Deimos’ rotations are first described by Eulerian rotational equations, and integrated simultaneously with the orbital motion equations. Orbital and orientational parameters of Mars satellites were simultaneously obtained by numerical integration for the first time. In order to compare the differences between our newly developed model and the one now used in the ephemerides, we first reproduced and simulated the current model using our own parameters, and then fit it to the Institut de Mécanique Céleste et de Calcul des Éphémérides ephemerides using least-square procedures. The adjustment test simulations show Phobos and Deimos’ orbital differences between the refined model and the current model are no more than 300 m and 125 m, respectively. The orientation parameters are confirmed and the results are in good agreement with the International Astronomical Union results. Moreover, we simulated two perturbations (main asteroids and mutual torques) which were not included in our refined model, and find that their effects on the orbits are completely negligible. As for the effect on rotation, we propose to take care of the role of mutual attraction in future models.

The ExoMars 2028 WISDOM antenna assembly: Description and characterization

While ground penetrating radars have been extensively researched on Earth, the high-resolution exploration and imaging of the shallow subsurface of celestial bodies in our solar system is still in its early stages, with only a handful of systems capable of the task.Designing high-resolution radar systems can be a complex task due to the large frequency bandwidth required by the antennas to achieve high vertical resolution. The WISDOM GPR, as part of the 2028 ExoMars mission, is a highly capable and challenging instrument in this context, given its fully-polarimetric setup and mission constraints on the operating environment, robustness, as well as mass and size budget.This paper outlines the development and characterization process of the WISDOM antenna assembly, which can serve as a model for future radar systems. Furthermore, it presents the results of the antenna characterization as the foundation for instrument calibration and optimal radar sounding outcomes.

Searching for Dark Matter Based on Gravitational Lensing

Gravitational lensing is a powerful astronomical tool in which scholars can accurately predict the distribution of dark matter in massive objects by observing the bending effects of light in the gravitational fields of huge objects (e.g., galaxies or galaxy clusters). Since dark matter does not emit directly, or is strongly interacts with ordinary matter, gravitational lensing gives us a unique view of observing and measuring dark matter. This study introduces some principles of gravitational lensing effect to provide favorable evidence in the study of dark matter and other celestial bodies (including an engineering study in the focal region of solar gravitational lensing (SGL) and other experiments). This research will see how the properties of the clear and focused gravitational lens are applied to celestial observations, and how they are captured by the detector. Strong gravitational lensing can better show distant galaxies (including high redshift) around the dark matter distribution, and through the several basic quantities in gravitational lens analytical and numerical calculation and analysis, to simulate the center of the supermassive black hole, and gravitational lensing image and model of dark matter mass can be detected and dark matter has the key evidences of the interaction. It reveals the intrinsic and distribution of dark matter, thus driving the understanding of the universe’s evolution and its fundamental components. Therefore, gravitational lensing has an irreplaceable value and a far-reaching influence in exploring the unsolved mystery of dark matter.

Review the formation and characteristics of black holes – examining the properties of Sgr A* centered at Milky Way

The black hole is one of the important celestial bodies in the universe, and understanding its properties is important to help us understand universe and our homeland Milky way. My aims are to explore the properties of center black hole on Milky Way, Sagittarius A (Sgr A*). I first review the properties of black hole in the literature, including the formation of black hole, classification, and observations of black holes. Then, I examine the properties of Sgr A*, exploring its mass-calculation based on observation and properties as supermassive black hole. Through this study, I find that Sgr A* can form from gravitational collapse of a massive cloud of gas and dust, properties and observations like accretion disk, gravitational influence, and gravitational waves it has as a supermassive black hole, and its mass can be calculated from star orbit. In summary, studying the properties of Sgr A* is crucial to understanding our galaxy, and the fundamental nature of the universe.

Analysis of the Current Status and Means of Studying Gravitational Lensing

Lens in physics is a kind of mirror that deflects light and results in a deflated and distorted image of the light-emitting object. Hence, the phenomenon of a massive celestial object deflecting light to form a distorted, magnified image of a luminous object is well known as gravitational lensing. In this paper, a brief summary of the concept and the status quo of the research and methodology related to it is rendered. This study offers a review of the overall founding history of the concept, and presents the current advances in relevant research. Later, the principles of generation and construction modeling of the concept, basic methodology are demonstrated. Subsequently, the applications of gravitational lensing in dark matter research, celestial body relationship research and validation of research results will be illustrated with examples of recent research. Then, the potential discrepancies in the use of gravitational lensing and future prospects are discussed in short. These results intended to help scholars who lack an understanding of the concept to have a primer on the field of gravitational lensing.

Sayyidāt al-Qamarسيدات القمر as Celestial Bodies: A Reading of Booth’s Award-Winning Translation

Sayyidāt al-Qamarسيدات القمر as Celestial Bodies: A Reading of Booth’s Award-Winning Translation

Comparison of On-Sky Wavelength Calibration Methods for Integral Field Spectrograph

With advancements in technology, scientists are delving deeper in their explorations of the universe. Integral field spectrograph (IFS) play a significant role in investigating the physical properties of supermassive black holes at the centers of galaxies, the nuclei of galaxies, and the star formation processes within galaxies, including under extreme conditions such as those present in galaxy mergers, ultra-low-metallicity galaxies, and star-forming galaxies with strong feedback. IFS transform the spatial field into a linear field using an image slicer and obtain the spectra of targets in each spatial resolution element through a grating. Through scientific processing, two-dimensional images for each target band can be obtained. IFS use concave gratings as dispersion systems to decompose the polychromatic light emitted by celestial bodies into monochromatic light, arranged linearly according to wavelength. In this experiment, the working environment of a star was simulated in the laboratory to facilitate the wavelength calibration of the space integral field spectrometer. Tools necessary for the calibration process were also explored. A mercury–argon lamp was employed as the light source to extract characteristic information from each pixel in the detector, facilitating the wavelength calibration of the spatial IFS. The optimal peak-finding method was selected by contrasting the center of weight, polynomial fitting, and Gaussian fitting methods. Ultimately, employing the 4FFT-LMG algorithm to fit Gaussian curves enabled the determination of the spectral peak positions, yielding wavelength calibration coefficients for a spatial IFS within the range of 360 nm to 600 nm. The correlation of the fitting results between the detector pixel positions and corresponding wavelengths was >99.99%. The calibration accuracy during wavelength calibration was 0.0067 nm, reaching a very high level.

Cross-Spectral Navigation with Sensor Handover for Enhanced Proximity Operations with Uncooperative Space Objects

Close-proximity operations play a crucial role in emerging mission concepts, such as Active Debris Removal or small celestial bodies exploration. When approaching a non-cooperative target, the increased risk of collisions and reduced reliance on ground intervention necessitate autonomous on-board relative pose (position and attitude) estimation. Although navigation strategies relying on monocular cameras which operate in the visible (VIS) spectrum have been extensively studied and tested in flight for navigation applications, their accuracy is heavily related to the target’s illumination conditions, thus limiting their applicability range. The novelty of the paper is the introduction of a thermal-infrared (TIR) camera to complement the VIS one to mitigate the aforementioned issues. The primary goal of this work is to evaluate the enhancement in navigation accuracy and robustness by performing VIS-TIR data fusion within an Extended Kalman Filter (EKF) and to assess the performance of such navigation strategy in challenging illumination scenarios. The proposed navigation architecture is tightly coupled, leveraging correspondences between a known uncooperative target and feature points extracted from multispectral images. Furthermore, handover from one camera to the other is introduced to enable seamlessly operations across both spectra while prioritizing the most significant measurement sources. The pipeline is tested on Tango spacecraft synthetically generated VIS and TIR images. A performance assessment is carried out through numerical simulations considering different illumination conditions. Our results demonstrate that a combined VIS-TIR navigation strategy effectively enhances operational robustness and flexibility compared to traditional VIS-only navigation chains.

СЕМАНТИЧЕСКАЯ БЛИЗОСТЬ АСТРОНОМИЧЕСКИХ ПОНЯТИЙ, ОБОЗНАЧАЮЩИХ НЕБЕСНЫЕ ТЕЛА

The problem of determining the semantic similarity of astronomical terms denoting celestial objects in a school astronomy course is considered. A distributive method is used, which consists in comparing the distributions of concepts in the astronomy textbook. With the help of special computer programs, punctuation marks and stop words are removed from the text, the number of mentions of various terms is deter-mined, the cosine measure of proximity and the semantic distance between concepts are calculated. This allows: 1) to reveal frequently used astronomical concepts denoting celestial bodies; 2) to obtain matrices of proximity and semantic distances between the concepts of "galaxy", "star", "Sun", "planet", "black hole", "white dwarf", etc.; 3) to create a mental map of the celestial bodies that make up the Solar system, taking into account the distances between the terms designating them 4) to build clouds of concepts "types of stars", "Earth – star – Universe". To model the semantic space of the textbook, the Graf.pas computer program is used, which randomly moves vertices in 2D or 3D space, each time calculating the potential energy W of the elastic rods connecting them and choosing such an arrangement of vertices that W is minimal. It is believed that the closely located vertices are connected by rigid rods, and the far removed ones are connected by elastic rubber threads.

Kepler’s problem of a two-body system perturbed by a third body

One of the most important problems in basic physics and astronomy is studying the motion of planets, satellites, and other celestial bodies. The solution to the two-body problem enables astronomers to predict the orbits of the Moon, satellites, and spaceships around the Earth. The general analytic solution for the three-body problem stands unsolved except in some special cases. This reduces the problem to a two-body problem. In this work, the authors present a closed-form approach to the three-body problem theoretically and numerically based on particle–particle vector analysis. The theoretical approach, which is based on the real Moon–Sun–Earth problem information, illustrates the perturbation of the Moon in the Sun–Earth problem and shows an expected orbital motion with a perturbation in the Sun–Earth orbit due to the revolution of the Moon. The numerical investigation uses the same information to study the same problem and calculate the angular momentums of each pair of objects. The two solutions show good agreement with the well-known Earth-Moon and Sun–Earth momentums. The Moon–Sun orbit is close to an elliptic shape with angular momentum of about 3.27 × 1038 J.s. This approach is the key to future studies for n-body problem solutions.

Contibutuins of Muslims to Fundamental Research

The period spanning from the eighth to the thirteenth centuries, often referred to as the Islamic Golden Age, was marked by significant advancements in human knowledge attributed to Muslim scholars. The influence of this era is still evident today through various aspects of our daily lives, including the numeral system we use, terms such as algebra, algorithm, and almanac, as well as the nomenclature of celestial bodies. Unfortunately, much of this historical significance remains overlooked, as contemporary views of the Islamic world have largely diminished appreciation for its rich intellectual heritage. In contrast, this article aims to present an alternative viewpoint that diverges from the narratives commonly portrayed in 24-hour news cycles and online platforms. It is crucial to acknowledge the enduring legacy of Muslim contributions to intellectual progress, which have been recognized within Western society.

From Newton's First Law to the Motion of Celestial Bodies

Newton's original work "Principles" was written in Latin. An English version translated two years after his death changed the first law from "in directum" to "in a right line." Later generations think that only static or uniform straight line motion is inertia, while excluding rotational motion. This article proposes that the gravitational potential energy of a planet's revolution is equal to its centrifugal kinetic energy (mυ2). The work done by an object is a process quantity, but kinetic energy is a state variable that can be divided into instantaneous kinetic energy and average kinetic energy. Uniform motion does not do work, and instantaneous kinetic energy in variable speed motion does not also do work, only the average kinetic energy of variable speed motion does work. Only the energy between work and the average kinetic energy of variable speed motion can be converted into each other. We have clarified the relationship between work and kinetic energy, completed the transition of the kinetic energy formula at low and high speeds, achieved the unification of the kinetic energy formula and the mass energy relationship formula, and explained the √2 factor in the escape velocity..

SETI at FAST in China

Abstract Since the commencement of the first SETI observation in 2019, China’s Search for Extraterrestrial Intelligence program has garnered momentum through domestic support and international collaborations. Several observations targeting exoplanets and nearby stars have been conducted with the Five-hundred-metre Aperture Spherical Telescope (FAST). In 2023 the introduction of the Far Neighbour Project (FNP) marked a substantial leap forward, driven by the remarkable sensitivity of the FAST telescope and some of the novel observational techniques. The FNP seeks to methodically detect technosignatures from celestial bodies, including nearby stars, exoplanetary systems, Milky Way globular clusters and more. This paper provides an overview of the progress achieved by SETI in China and offers insights into the distinct phases comprising the FNP. Additionally it underscores the significance of this project’s advancement and its potential contributions to the field.

Feasibility of a Fiber-Dispersive Raman Spectrometer for Biomarker Detection.

Raman spectroscopy is among the top analytical techniques for ultra-low-dense organic matter, crucial to the search for life and analysis of celestial body surfaces in space exploration missions. Achieving the ultimate sensitivity of in-situ Raman spectroscopy necessitates a breakthrough in detecting inelastically scattered light. Single-photon detectors (SPDs) operating in photon counting mode, which can differentiate between Raman and luminescence responses, are promising candidates for the challenging scientific requirements. Since large SPD arrays are not yet commercially available, a dispersive element can be adapted to a single-pixel detector. By exploiting chromatic dispersion in optical fibers and picosecond-pulsed excitation, we delay the arrivals of different spectral components onto a single-pixel SPD. This method also separates weak Raman signals from stronger luminescence through correlated time-domain measurements. We study the impact of fiber properties and the excitation wavelength of a pulsed laser on the spectral resolution of the fiber-dispersive Raman spectrometer (FDRS). Additionally, we demonstrate the FDRS's potential for studying biomarkers and discuss its feasibility for analyzing inclusions in ice matrices.

Intensity-sensitive Quality Assessment of Extended Sources in Astronomical Images

Radio astronomy studies the Universe by observing the radio emissions of celestial bodies. Different methods can be used to recover the sky brightness distribution (SBD), which describes the distribution of celestial sources from recorded data, with the output dependent on the method used. Image quality assessment (IQA) indexes can be used to compare the differences between restored SBDs produced by different image reconstruction techniques to evaluate their effectiveness. However, reconstructed images (for the same SBD) can appear to be very similar, especially when observed by the human visual system (HVS). Hence, current structural similarity methods, inspired by the HVS, are not effective. In the past, we have proposed two methods to assess point-source images, where low amounts of concentrated information are present in larger regions of noise-like data. But for images that include extended source(s), the increase in complexity of the structure makes the IQA methods for point sources oversensitive because the important objects cannot be described by isolated point sources. Therefore, in this article we propose the augmented low-information similarity index (augLISI), an improved version of LISI, to assess images including extended source(s). Experiments have been carried out to illustrate how this new IQA method can help with the development and study of astronomical imaging techniques. Note that although we focus on radio astronomical images herein, these IQA methods are also applicable to other astronomical images and imaging techniques.