Orbital Properties Research Articles

Experimental and theoretical investigations of Ethyltriphenylphosphonium bromide dihydrate crystal for optical applications

The organic Ethyltriphenylphosphonium bromide dihydrate (ETPBD) single crystal is grown by slow evaporation method at room temperature. The unit cell parameters and crystal system were obtained by the single crystal X-ray diffraction technique. The optical parameters and absorption wavelength assessment are made by UV–Visible spectroscopic technique. The second harmonic generated efficiency is evaluated by using the Kurtz-Perry technique. The polarizability value, charge distribution, HOMO-LUMO energy, natural bond orbital and thermodynamical properties of the ETPBD crystal are estimated from the quantum chemical calculation with the help of DFT. The intermolecular interaction of ETPBD crystal is also analyzed by Hirshfeld surface analysis. The various functional groups were analyzed by spectroscopic studies of FTIR and FTRAMAN by experimentally identified functional groups that were compared with theoretically computed values.

Orbital dynamics and histories of satellite galaxies around Milky Way – mass galaxies in the FIRE simulations

ABSTRACT The orbits of satellite galaxies encode rich information about their histories. We investigate the orbital dynamics and histories of satellite galaxies around Milky Way (MW)-mass host galaxies using the FIRE-2 cosmological simulations, which, as previous works have shown, produce satellite mass functions and spatial distributions that broadly agree with observations. We first examine trends in orbital dynamics at z = 0, including total velocity, specific angular momentum, and specific total energy: the time of infall into the MW-mass halo primarily determines these orbital properties. We then examine orbital histories, focusing on the lookback time of first infall into a host halo and pericentre distances, times, and counts. Roughly 37 per cent of galaxies with $M_{\rm star}\lesssim 10^7\, {\rm M}_{\odot }$ were ‘pre-processed’ as a satellite in a lower-mass group, typically $\approx 2.7\, {\rm Gyr}$ before falling into the MW-mass halo. Half of all satellites at z = 0 experienced multiple pericentres about their MW-mass host. Remarkably, for most (67 per cent) of these satellites, their most recent pericentre was not their minimum pericentre: the minimum typically was ∼40 per cent smaller and occurred $\sim 6\, {\rm Gyr}$ earlier. These satellites with growing pericentres appear to have multiple origins: for about half, their specific angular momentum gradually increased over time, while for the other half, most rapidly increased near their first apocentre, suggesting that a combination of a time-dependent MW-mass halo potential and dynamical perturbations in the outer halo caused these satellites’ pericentres to grow. Our results highlight the limitations of idealized, static orbit modelling, especially for pericentre histories.

Prediction of an Earth-sized Planet Formed in the Habitable Zone of the SPECULOOS-2 System

Transiting planets in the nearby TRAPPIST-1 system provide rare examples of habitable zone (HZ), Earth-sized planets that can be characterized via transmission spectroscopy. However, these present-day HZ planets likely formed interior to HZ and probably underwent an evolution very different from that of Earth. We present the integrative analysis of the planetary architecture of the recently discovered planetary system SPECULOOS-2. Our analysis answers the question: If there are additional exoplanets in the SPECULOOS-2 system, what are their orbital and physical properties? We predict an Earth-sized planet in the habitable zone (P ∼ 14.5–18.2 days). In contrast to TRAPPIST-1e, this predicted planet most likely completed its formation inside the habitable zone. If confirmed, this planet will offer an Earth-sized, habitable zone planet that is likely to have an evolutionary path more similar to Earth than those in the TRAPPIST-1 system.

Shedding light on low-mass subhalo survival and annihilation luminosity with numerical simulations

ABSTRACT In this work, we carry out a suite of specially designed numerical simulations to shed light on dark matter (DM) subhalo survival at mass scales relevant for gamma-ray DM searches, a topic subject to intense debate nowadays. We have employed an improved version of DASH, a GPU N-body code, to study the evolution of low-mass subhaloes inside a Milky-Way-like halo with unprecedented accuracy, reaching solar-mass and sub-parsec resolution. We simulate subhaloes with varying mass, concentration, and orbital properties, and consider the effect of baryons in the host. We analyse the evolution of the bound mass fraction and annihilation luminosity, finding that most subhaloes survive until present, yet losing in some cases more than 99 per cent of their initial mass. Baryons induce a much greater mass-loss, especially when the subhalo orbit is more parallel to the Galactic disc. Many of these subhaloes cross the solar Galactocentric radius, making it easier to detect their annihilation fluxes from Earth. We find subhaloes orbiting a DM-only halo with a pericentre in the solar vicinity to lose 70–90 per cent of their initial annihilation luminosity at present, which increases up to 99 per cent when including baryons. We find a strong relation between subhalo’s mass-loss and the effective tidal field at pericentre. Indeed, much of the dependence on all considered parameters can be explained through this single parameter. In addition to shedding light on the survival of low-mass Galactic subhaloes, our results can provide detailed predictions that will aid current and future quests for the nature of DM.

Orbital order and ferromagnetism in LaMn[formula omitted]Ga[formula omitted]O[formula omitted

We study from first principles the magnetic, electronic, orbital and structural properties of the LaMnO3 doped with gallium replacing the Mn-site. The gallium doping reduces the Jahn–Teller effect, and consequently the bandgap. Surprisingly, the system does not go towards a metallic phase because of the Mn-bandwidth reduction. The Ga-doping tends to reduce the orbital order typical of bulk antiferromagnetic LaMnO3 and consequently weakens the antiferromagnetic phase. The Ga-doping favors the G-type orbital order and layered-ordered ferromagnetic perovskite at x=0.50, both effects contribute to the formation of the insulating ferromagnetic phase in LaMn1−xGaxO3.

Momentum Enhancement during Kinetic Impacts in the Low-intermediate-strength Regime: Benchmarking and Validation of Impact Shock Physics Codes

In 2022 September, the DART spacecraft (NASA’s contribution to the Asteroid Impact & Deflection Assessment (AIDA) collaboration) will impact the asteroid Dimorphos, the secondary in the Didymos system. The crater formation and material ejection will affect the orbital period. In 2027, Hera (ESA’s contribution to AIDA) will investigate the system, observe the crater caused by DART, and characterize Dimorphos. Before Hera’s arrival, the target properties will not be well-constrained. The relationships between observed orbital change and specific target properties are not unique, but Hera’s observations will add additional constraints for the analysis of the impact event, which will narrow the range of feasible target properties. In this study, we use three different shock physics codes to simulate momentum transfer from impactor to target and investigate the agreement between the results from the codes for well-defined target materials. In contrast to previous studies, care is taken to use consistent crushing behavior (e.g., distension as a function of pressure) for a given porosity for all codes. First, we validate the codes against impact experiments into a regolith simulant. Second, we benchmark the codes at the DART impact scale for a range of target material parameters (10%–50% porosity, 1.4–100 kPa cohesion). Aligning the crushing behavior improves the consistency of the derived momentum enhancement between the three codes to within +/−5% for most materials used. Based on the derived mass–velocity distributions from all three codes, we derive scaling parameters that can be used for studies of the ejecta curtain.

Pushing least-squares deconvolution to the next level: Application to binary stars

Context. Eclipsing, spectroscopic double-lined (SB2) binaries remain the prime source of precise and accurate fundamental properties of stars. Furthermore, high-cadence spectroscopic observations of the eclipse phases allow us to resolve the Rossiter-McLaughlin (RM) effect, whose modelling offers the means to probe spin-orbit misalignment in binaries. Aims. We aim to develop a method that provides precise and accurate measurements of radial velocities (RVs) of both binary components, including the in-eclipse orbital phases where line profiles are subject to large distortions due to the RM effect. We also intend to separate spectral contributions of the primary and secondary components in the velocity space in order that a time series of the separated spectroscopic signals can be obtained throughout the binary orbit, preserving any line-profile variability (LPV) that might be present in either or both of those spectroscopic contributions. Methods. In this study, we provide a generalisation of the least-squares deconvolution (LSD) method to SB2 systems. Our LSD-Binary algorithm is capable of working with both in-eclipse and out-of-eclipse spectra as input, and delivers the LSD profiles, LSD-based model spectra, and precise RVs of both binary components as output. We offer an option to account for the RM effect in the calculation of the initial guess LSD profiles and components’ flux ratio, such that the effect can be modelled within the algorithm itself. In that case, the algorithm delivers both the LSD profiles and RVs, which are no longer distorted by the RM effect. Otherwise, when geometry of the RM effect is ignored in the calculation of the initial guess, the LSDBinary algorithm delivers an RV curve that contains contributions from both the orbital motion of the star and spectral line distortions due to the RM effect. Results. In this study, we provide an extensive test of the LSDBinary software package on simulated spectra of artificial binaries resembling Algol-type systems and detached binaries with similar components. We study the effects of signal-to-noise ratios (S/N) of input spectra, the resolving power of the instrument, uncertain atmospheric parameters of stars, and orbital properties of the binary system on the resulting LSD profiles and RVs measured from them. We find that atmospheric parameters have a negligible effect on the shape of the computed LSD profiles while affecting mostly their global scaling. High-resolution (R ≳ 60 000) spectroscopic observations are required in order to investigate the RM effect in detail, although a medium resolving power of R ≈ 25 000–30 000 might suffice when the amplitude of the effect is large. Our results are barely sensitive to the S/N of the input spectra provided they contain a sufficient number of spectral lines, such as in A-type and later stars. Finally, the orbital inclination angle and the components’ radii ratio are found to have the largest effect on the shapes of the LSD profiles and RV curves extracted from them. Conclusions. The LSDBinary algorithm is specifically developed to perform detailed spectroscopic studies of eclipsing SB2 systems whose orbital configuration and components’ atmospheric parameters are estimated by other means. The algorithm is well suited to study the RM effect, as well as to compute the separated LSD profiles of both binary components from the observed composite in-eclipse spectra of SB2 systems.

Study on the activation mechanism of protactinium and NH3 by density functional theory

The interaction of Protactinium with NH3 was analyzed by Density Functional Theory. We obtained the dehydrogenation paths with the lowest energy and plotted the potential energy surfaces (PESs). At the same time, the intersection of the PES is discussed by minimum energy crossing point (MECP). Combined with topological analysis, the bonding properties were systematically explored, and the 5f orbital properties and charge changes were explained by the nature bond orbital (NBO). The results shown that 5f electrons are not conducive to the reaction progress. Finally, the reaction rate of the transition state was discussed in detail by using the variational transition state theory (VTST).

Four-body cislunar quasi-periodic orbits and their application to ballistic lunar transfer design

Examining the properties of quasi-periodic orbits provides insight into the Sun-perturbed environment in cislunar space. In this investigation, quasi-periodic trajectories and their properties are explored in the Sun-Earth-Moon four-body problem. Computation and the stability characteristics of families of invariant tori are detailed. Furthermore, this investigation offers a framework for construction of ballistic lunar transfer trajectories in the four-body problem. The framework leverages manifold trajectories to supply a set of initial conditions for construction of periapsis Poincaré maps. Periapsis maps reduce the dimensionality of the space and illuminate solutions of interest as a basis to produce feasible families of transfers. Through a continuation process, families of ballistic transfers and families of transfers that include powered lunar flybys are constructed. Ultimately, these solutions supply an initial guess for transition to the Sun-Earth-Moon ephemeris model.

Spectral (FT-IR, FT-Raman, NMR, UV–vis), electronic structure (DFT, TD-DFT), and molecular docking investigations on 1-((1H-benzo[d]imidazol-1-yl)methyl)urea – A bioactive Mannich base system

A synthesized 1-((1H-benzo[d]imidazol-1-yl)methyl)urea (BFU) Mannich base has been extensively studied using experimental and theoretical techniques. Rotamerism, geometry, tautomerism and mechanistic aspects of tautomerism were investigated. Spectral studies were carried out which includes FT-IR, FT-Raman, NMR, and UV–vis spectral characterization. Electronic structure properties such as frontier molecular orbital analysis, molecular electrostatic potential, atomic charges, natural bond orbital characterization and NLO properties enhance insight into the chemical physics nature of BFU. Real space wave function analyses edify the nature of intramolecular interactions. Molecular docking analysis has been performed against a fungal species called C. glabrata whose protein ID is 5B6K with BFU.

NEOSSat observations of three transiting hot Jupiters

Abstract The Near Earth Object Surveillance Satellite (NEOSSat) is a Canadian-led 15 cm Earth-orbiting telescope originally designed to detect asteroids near the Sun. Its design is however also suitable for the observation of exoplanetary transits of bright stars. We used the NEOSSat platform to perform followup observations of several Transiting Exoplanets Survey Satellite (TESS) targets, both as a demonstration of NEOSSat capabilities for exoplanetary science and improve the orbital ephemerides and properties of these exoplanet systems. We are able to recover / confirm the orbital properties of such targets to within mutual error bars, demonstrating NEOSSat as a useful future contributor to exoplanetary science.

Cluster environment quenches the star formation of low-mass satellite galaxies from the inside-out

ABSTRACT Environment plays a critical role in the star formation history of galaxies. Tidal and hydrodynamical stripping, prominent in cluster environment, can remove the peripheral gas of galaxies and star formation may thus be environmentally suppressed from the outside-in. We revisit the environmental dependence of the radial gradient of specific star formation rate (sSFR) profile. We probe the radial gradient by using the archival spectral indices D4000n and HδA measured from SDSS fibre spectra, to indicate central sSFR and the total sSFR from fitting the spectral energy distribution. Despite the low spatial resolution, the wealth of SDSS data allows to disentangle the dependences on stellar mass, sSFR, and environment. We find that low-mass satellite galaxies in the mass range $9\lt \mathrm{log}\, \mathcal {M}_{\star }/\mathcal {M}_{\odot }\lt 9.8$ on average quench in more inside-out pattern compared to isolated galaxies matched in mass, sSFR, and fibre coverage. This environmental effect is particularly strong for galaxies below the star formation main sequence, and peaks for those in the core of massive clusters where the phase-space diagram reveals clear links between the inside-out quenching and orbital properties. Our results suggest that both tidal and hydrodynamical interactions in cluster environment suppress the star formation of satellites mainly from the inside-out. As accreted gas of low angular momentum from hot gas haloes is an important source for replenishing central gas reservoir, we discuss how gas stripping in clusters may lead to starvation and cause inside-out quenching when the outer star-forming discs are not significantly affected.

Gastro Library. I. The Simulated Chemodynamical Properties of Several Gaia–Sausage–Enceladus-like Stellar Halos

The Milky Way (MW) stellar halo contains relics of ancient mergers that tell the story of our galaxy’s formation. Some of them are identified due to their similarity in energy, actions, and chemistry, referred to as the “chemodynamical space,” and are often attributed to distinct merger events. It is also known that our galaxy went through a significant merger event that shaped the local stellar halo during its first billion years. Previous studies using N-body only and cosmological hydrodynamical simulations have shown that such a single massive merger can produce several “signatures” in the chemodynamical space, which can potentially be misinterpreted as distinct merger events. Motivated by these, in this work we use a subset of the GASTRO library, which consists of several smoothed particle hydrodynamics+N-body models of a single accretion event in a MW-like galaxy. Here, we study models with orbital properties similar to the main merger event of our galaxy and explore the implications to known stellar halo substructures. We find that (i) supernova feedback efficiency influences the satellite’s structure and orbital evolution, resulting in distinct chemodynamical features for models with the same initial conditions; (ii) very retrograde high-energy stars are the most metal-poor of the accreted dwarf galaxy and could be misinterpreted as a distinct merger; (iii) the most bound stars are more metal-rich in our models, the opposite of what is observed in the MW, suggesting a secondary massive merger; and, finally, (iv) our models can reconcile other known apparently distinct substructures to a unique progenitor.

4 Boyutlu Modelde Spinör Tipi İnstanton Çözümlerinin Dalgacık Entropisinin İncelenmesi

In recent years, many methods have been proposed in various fields to investigate the properties of orbits of nonlinear dynamical systems. In this study, the characteristics of the orbits of spinor-type instanton solutions in the four-dimensional Gursey model via Heisenberg ansatz is investigated. The orbits of spinor-type instanton solutions are analyzed by Shannon wavelet entropy (WE) method. In order to analyze the regular or irregular states of the orbits of spinor-type instanton solutions, WE spectrum and WE in phase space are studied. It is observed that spinor-type instanton solutions have regular orbits around the fixed point and irregular orbits for other points. According to this study, WE can be used to observe the entropy evolution of nonlinear dynamical systems in phase space.

Transit Light Curves for Exomoons: Analytical Formalism

The photometric transit method has been the most effective method to detect and characterize exoplanets as several ground based as well as space based survey missions have discovered thousands of exoplanets using this method. With the advent of the upcoming next generation large telescopes, the detection of exomoons in a few of these exoplanetary systems is very plausible. In this paper, we present a comprehensive analytical formalism in order to model the transit light curves for such moon-hosting exoplanets. In order to achieve analytical formalism, we have considered circular orbit of the exomoon around the host planet, which is indeed the case for tidally locked moons. The formalism uses the radius and orbital properties of both the host planet and its moon as model parameters. The coalignment or noncoalignment of the orbits of the planet and the moon are parameterized using two angular parameters and thus can be used to model all the possible orbital alignments for a star–planet–moon system. This formalism also provides unique and direct solutions to every possible star–planet–moon three circular body alignment. Using the formula derived, a few representative light curves are also presented.

Reduced Variations in Earth’s and Mars’ Orbital Inclination and Earth’s Obliquity from 58 to 48 Myr ago due to Solar System Chaos

The dynamical evolution of the solar system is chaotic with a Lyapunov time of only ∼5 Myr for the inner planets. Due to the chaos it is fundamentally impossible to accurately predict the solar system’s orbital evolution beyond ∼50 Myr based on present astronomical observations. We have recently developed a method to overcome the problem by using the geologic record to constrain astronomical solutions in the past. Our resulting optimal astronomical solution (called ZB18a) shows exceptional agreement with the geologic record to ∼58 Ma (Myr ago) and a characteristic resonance transition around 50 Ma. Here we show that ZB18a and integration of Earth’s and Mars’ spin vector based on ZB18a yield reduced variations in Earth’s and Mars’ orbital inclination and Earth’s obliquity (axial tilt) from ∼58 to ∼48 Ma—the latter being consistent with paleoclimate records. The changes in the obliquities have important implications for the climate histories of Earth and Mars. We provide a detailed analysis of solar system frequencies (g and s modes) and show that the shifts in the variation in Earth’s and Mars’ orbital inclination and obliquity around 48 Ma are associated with the resonance transition and caused by changes in the contributions to the superposition of s modes, plus g–s mode interactions in the inner solar system. The g–s mode interactions and the resonance transition (consistent with geologic data) are unequivocal manifestations of chaos. Dynamical chaos in the solar system hence not only affects its orbital properties but also the long-term evolution of planetary climate through eccentricity and the link between inclination and axial tilt.

Comparing thin accretion disk properties of naked singularities and black holes

In the present paper, we study the thermal properties of the geometrically thin accretion disks surrounding the null naked singularity (NNS) and the first type of Joshi-Malafarina-Narayan (JMN1) spacetimes and compare the results with the accretion disk around equally massive Schwarzschild black hole. First, we examine the properties of the circular orbits in these spacetimes. The emitted flux, radiation spectra, disk efficiency, and temperature distribution on the disk surface are then investigated. The efficiency of the conversion of the accreting matter into radiation is found to be substantially higher for naked singularities than that for black holes. We also verify that the flux radiated from the disk surface is greater for null and JMN1 naked singularities than black holes. Hence, the accretion disks around naked singularities are much more luminous than the black holes of the same mass and accretion rate. In the luminosity spectra of the NNS, we find that the significant contribution of the low-frequency is coming from the nearby regions of the NNS. Furthermore, the spectral luminosity distribution for the ``nonzero torque'' at the inner boundary is also analyzed by the inclusion of the nonzero torque value at the inner edge of the disk. The slopes of the luminosity distribution with respect to frequency for naked singularity spacetimes differ significantly from those of black holes. These unique features of the naked singularities serve as an effective tool to distinguish them from the equally massive black holes.

Unravelling the thermodynamics and binding interactions of bovine serum albumin (BSA) with thiazole based carbohydrazide: Multi-spectroscopic, DFT and molecular dynamics approach

In the present manuscript, a novel 2-((4-chlorophenyl)amino)-N'-(4-(diethylamino)-2-hydroxybenzylidene)thiazole-4-carbohydrazide (H1) has been synthesized and characterized using various spectroscopic techniques including 1D, 2D NMR, FT-IR and single-crystal XRD. Various electrostatic parameters such as frontier molecular orbital (FMO), natural bond orbital (NBO), Fukui functions and nonlinear optical (NLO) properties were explored by Density Functional Theory (DFT) using B3LYP/6-311+G(d,p) level of theory. The effect of solvent polarity on electronic absorption spectra was investigated using Time dependent-DFT. The thermodynamic parameters such as heat capacity, entropy and enthalpy were also investigated at different temperatures. Moreover, photophysical studies were performed to examine the effect of solvent polarity and viscosity. A positive solvatochromism and a 7 fold fluorescence enhancement were observed with the increase of solvent polarity and viscosity, respectively. The compound exhibit aggregation-induced emission in THF:H2O system. The binding interaction of H1 with BSA and its mechanism has been investigated using UV-visible absorption and fluorescence quenching techniques. The thermodynamics of binding suggest the presence of spontaneous hydrogen bonding interactions, as –ve values of ΔG, ΔS and ΔH were observed. The experimental results obtained from BSA binding studies were validated through in silico molecular docking and dynamics techniques. Molecular modelling studies perfectly corroborate the experimentally obtained results.

Analytical model of satellite motion in almost circular orbits under the influence of zonal harmonics of geopotential

The article deals with the movement of satellites in low near-circular orbits of the Earth. An analytical model is constructed, which consists of formulas describing the change of the osculating elements and averaged equations. An algorithm for constructing a second approximation of the influence of zonal harmonics of the geopotential on the movement of satellites in almost circular orbits is presented. For the second and third zonal harmonics, formulas are given for the osculating and average elements describing the motion of the satellite in the second approximation in small parameters. The introduction of special variables for almost circular orbits made it possible to significantly simplify the procedure for constructing the second approximation of the influence of zonal harmonics. The article provides a justification for the accuracy of the analytical model for the considered orbits. The constructed model of changes in the average elements of the orbit describes the basic principles of motion. With a sufficiently high accuracy, this model describes the changes in the average elements of the orbit with simple analytical formulas and is convenient for analyzing the properties of orbits and pre-selecting a reference orbit for a specific mission.

Systematic light-curve modelling of TDEs: statistical differences between the spectroscopic classes

ABSTRACT With the sample of observed tidal disruption events (TDEs) now reaching several tens, distinct spectroscopic classes have emerged: TDEs with only hydrogen lines (TDE-H), only helium lines (TDE-He), or hydrogen in combination with He ii and often N iii/O iii (TDE-H + He). Here, we model the light curves of 32 optically bright TDEs using the Modular Open Source Fitter for Transients (mosfit) to estimate physical and orbital properties, and look for statistical differences between the spectroscopic classes. For all types, we find a shallow distribution of star masses, compared to a typical initial mass function, in the range ∼0.1–1 M⊙, and no TDEs with very deep encounters. Our main result is that TDE-H events appear to come from less complete disruptions (and possibly lower SMBH masses) than TDE-H+He, with TDE-He events fully disrupted. We also find that TDE-H events have more extended photospheres, in agreement with recent literature, and argue that this could be a consequence of differences in the self-intersection radii of the debris streams. Finally, we identify an approximately linear correlation between black hole mass and radiative efficiency. We suggest that TDE-H may be powered by collision-induced outflows at relatively large radii, while TDE-H + He could result from prompt accretion discs, formed more efficiently in closer encounters around more massive SMBHs.