Moderate Eccentricity Research Articles

Origins of Super Jupiters: TOI-2145b has a Moderately Eccentric and Nearly Aligned Orbit

Super Jupiters are giant planets with several Jupiter masses. It remains an open question whether these planets originate with such high masses or grow through collisions. Previous work demonstrates that warm super Jupiters tend to have more eccentric orbits compared to regular-mass warm Jupiters. This correlation between mass and eccentricity may indicate that planet–planet interactions significantly influence the warm giant planet demographics. Here, we conducted a detailed characterization of a warm super Jupiter, TOI-2145b. This analysis utilized previous observations from Transiting Exoplanet Survey Satellite and Keck/High Resolution Echelle Spectrometer, enhanced by new Rossiter–McLaughlin effect data from the NEID spectrometer on the 3.5 m WIYN Telescope. TOI-2145b is a 5.68−0.34+0.37 M Jup planet on a moderate eccentricity (e = 0.214−0.014+0.014 ), 10.26 day orbit, orbiting an evolved A-star. We constrain the projected stellar obliquity to be λ = 6.8−3.8+2.9 ° from two NEID observations. Our N-body simulations suggest that the formation of super Jupiter TOI-2145b could involve either of two scenarios: a high initial mass or growth via collisions. On a population level, however, the collision scenario can better describe the mass–eccentricity distribution of observed warm Jupiters.

A Testbed for Tidal Migration: The 3D Architecture of an Eccentric Hot Jupiter HD 118203 b Accompanied by a Possibly Aligned Outer Giant Planet

Characterizing outer companions to hot Jupiters plays a crucial role in deciphering their origins. We present the discovery of a long-period giant planet, HD 118203 c ( mc=11.79−0.63+0.69MJ , ac=6.28−0.11+0.10 au) exterior to a close-in eccentric hot Jupiter HD 118203 b (P b = 6.135 days, m b = 2.14 ± 0.12 M J, r b = 1.14 ± 0.029 R J, e b = 0.31 ± 0.007) based on 20 yr radial velocities (RVs). Using Rossiter–McLaughlin (RM) observations from the Keck Planet Finder, we measured a low sky-projected spin–orbit angle λb=−11°7−10.0+7.6 for HD 118203 b and detected stellar oscillations in the host star, confirming its evolved status. Combining the RM observation with the stellar inclination measurement, we constrained the true spin–orbit angle of HD 118203 b as Ψ b < 33.°5 (2σ), indicating the orbit normal of the hot Jupiter nearly aligned with the stellar spin axis. Furthermore, by combining RVs and Hipparcos-Gaia astrometric acceleration, we constrained the line-of-sight mutual inclination between the hot Jupiter and the outer planet to be 9.°8−9.3+16.2 at the 2σ level. HD 118203 is one of first hot Jupiter systems where both the true spin–orbit angle of the hot Jupiter and the mutual inclination between inner and outer planets have been determined. Our results are consistent with a system-wide alignment, with low mutual inclinations between the outer giant planet, the inner hot Jupiter, and the host star. This alignment, along with the moderate eccentricity of HD 118203 c, implies that the system may have undergone coplanar high-eccentricity tidal migration. Under this framework, our dynamical analysis suggests an initial semimajor axis of 0.3–3.2 au for the proto–hot Jupiter.

Searching for compact hierarchical triple system candidates in astrometric binaries and accelerated solutions

Compact hierarchical triple (CHT) systems, where a tertiary component orbits an inner binary, provide critical insights into stellar formation and evolution. Despite their importance, the detection of such systems, especially compact ones, remains challenging due to the complexity of their orbital dynamics and the limitations of traditional observational methods. This study aims to identify new CHT star systems among \ astrometric binaries and accelerated solutions by analysing the radial velocity (RV) amplitude of these systems, thereby improving our understanding of stellar hierarchies. We selected a sample of bright astrometric binaries and accelerated solutions from the DR3 Non-Single Stars catalogue. The RV peak-to-peak amplitude was used as an estimator, and we applied a new method to detect potential triple systems by comparing the RV-based semi-amplitude with the astrometric semi-amplitude. We used available binary and triple star catalogues to identify and validate candidates, with a subset confirmed through further examination of the RV and astrometric data. Our analysis resulted in the discovery of $956$ CHT candidates among the orbital sources as well as another $3,115$ probable close binary sources in stars with accelerated solutions. Exploring the inclination, orbital period, and eccentricity of the outer companion in these CHT systems provides strong evidence of mutual orbit alignment, as well as a preference towards moderate outer eccentricities. Our novel approach has proven effective in identifying potential triple systems, thereby increasing their number in the catalogues. Our findings emphasise the importance of combined astrometric and RV data analysis in the study of multiple star systems.

Very metal-poor stars I: a catalogue derived from LAMOST DR9

ABSTRACT In this paper, a semisupervised machining learning technique had been utilized to analyse low-resolution stellar spectra from Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) Data Release 9 (DR9). We identified approximately 111 000 potential very metal-poor stars. Estimation of their stellar parameters ($T_{\rm eff}$, ${\rm log}\, \rm {g}$, [Fe/H]) indicate that over 99 per cent are metal-poor ([Fe/H] &amp;lt; −1.0), comprising 32 631 very metal-poor ([Fe/H] &amp;lt; −2.0), 702 extremely metal-poor ([Fe/H] &amp;lt; −3.0) and 30 ultra metal-poor ([Fe/H] &amp;lt; −4.0) stars. Based on kinematic characteristics, stars were categorized into thick disc-like, thin disc-like, and halo-like groups. We analysed their metallicity distributions (MDs) with respect to vertical height ($|Z|$) and orbital eccentricity (e). Thick disc-like stars in current sample show a clear trend of decreasing metallicty with increasing $|Z|$ or e for the ranges −3.0 $\lt $ [Fe/H] $\lt $ −1.2 and $|Z|$$\lt $ 3 kpc. Conversely, thin disc-like stars in current sample exhibit a slight increase in the fraction of more metal-poor stars with $|Z|$ for the ranges −3.0 $\lt $ [Fe/H] $\lt $ −1.2 and $|Z|$$\lt$ 1 kpc, but no obvious correlation with e. Additionally, we confirmed the presence of two prominent substructures among halo-like stars. One exhibits a high eccentricity ($e\ \gt\ 0.8$) orbit and higher metallicity, while the other follows a retrograde orbit with moderate eccentricity ($e\sim 0.6$) and lower metallicity. We believe they are related to the merger events known as Gaia Sausage and Sequoia, respectively. Furthermore, our observations indicate that the Sequoia has lower eccentricity and metallicity compared to the Gaia Sausage.

NGTS-30 b/TOI-4862 b: An ~1 Gyr old 98-day transiting warm Jupiter

Long-period transiting exoplanets bridge the gap between the bulk of transit- and Doppler-based exoplanet discoveries, providing key insights into the formation and evolution of planetary systems. The wider separation between these planets and their host stars results in the exoplanets typically experiencing less radiation from their host stars; hence, they should maintain more of their original atmospheres, which can be probed during transit via transmission spectroscopy. Although the known population of long-period transiting exoplanets is relatively sparse, surveys performed by the Transiting Exoplanet Survey Satellite (TESS) and the Next Generation Transit Survey (NGTS) are now discovering new exoplanets to fill in this crucial region of the exoplanetary parameter space. This study aims to characterise a new long-period transiting exoplanet by following up on a single-transit candidate found in the TESS mission. The TOI-4862 system was monitored using a combination of photometric instruments (TESS, NGTS, and EulerCam) and spectroscopic instruments (CORALIE, FEROS, HARPS, and PFS) in order to determine the period, radius, and mass of the long-period transiting exoplanet NGTS-30\,b/TOI-4862\,b. These observations were then fitted simultaneously to determine precise values for the properties and orbital parameters of the exoplanet, as well as the refined stellar parameters of the host star. We present the discovery of a long-period (P = 98.29838pm 0.00010 day) Jupiter-sized (0.928pm 0.032 R$_ J $; 0.960pm 0.056 M$_ J $) planet transiting a 1.1 Gyr old G-type star, one of the youngest warm Jupiters discovered to date. NGTS-30\,b/TOI-4862\,b has a moderate eccentricity $), meaning that its equilibrium temperature can be expected to vary from 274$^ $ K to 500$^ $ K over the course of its orbit. Through interior modelling, NGTS-30\,b/TOI-4862\,b was found to have a heavy element mass fraction of $ $ and a heavy element enrichment ($ p / Z_ star $) of $20^ $, making it metal-enriched compared to its host star. NGTS-30\,b/TOI-4862\,b is one of the youngest well-characterised long-period exoplanets found to date and will therefore be important in the quest to understanding the formation and evolution of exoplanets across the full range of orbital separations and ages.

The orbit of HD 142527 B is too compact to explain many of the disc features

Context. HD 142527 A is a young and massive Herbig Ae/Be star surrounded by a highly structured disc. The disc shows numerous morphological structures, such as spiral arms, a horseshoe region of dust emission, a set of shadows cast by an inner disc on the outer disc, and a large cavity extending from ≃30 au to ≃130 au. HD 142527 A also has a lower mass companion, HD 142527 B (M = 0.13 ± 0.03 M⊙), which is thought to be responsible for most of the structures observed in the surrounding disc. Aims. We aim to fully constrain the orbit of HD 142527 B and determine whether the binary alone is truly responsible for the observed morphology of the HD 142527 disc. Methods. We gathered VLTI/GRAVITY observations of HD 142527, either from our own programmes or from the ESO archive. We used this inhomogeneous set of data to extract a total of seven high-precision measurements of the relative astrometry between HD 142527 A and B, spread from mid-2017 to early 2021. Combined with what is available in the literature, these new measurements offer a total of 9 yr of astrometric monitoring on HD 142527. We used orbit fitting tools to determine the orbital parameters of HD 142527 B, and used them as inputs for a 3D hydrodynamical model of the disc to determine whether or not the binary is able to create the structures observed in the disc. Results. Our VLTI/GRAVITY astrometry gives excellent constraints on the orbit of HD 142527 B. We show that the secondary is following an orbit of semi-major axis a = 10.80 ± 0.22 au, with moderate eccentricity (e = 0.47 ± 0.01), and has recently passed its periapsis (τ = 2020.42). With such a compact orbit, we show that HD 142527 B can only generate a gap and spiral arms of ~30 au in the disc, which is much smaller than what is revealed by observations. Conclusions. Even from a theoretical standpoint, the observed cavity size of ~ 100 au far exceeds even the most generous predictions for a companion like HD 142527 B on such a compact orbit. Thus, we conclude that the low-mass companion cannot be solely responsible for the observed morphology of the disc surrounding the system.

Two Long-period Giant Planets around Two Giant Stars: HD 112570 and HD 154391

We present the discoveries of two giant plants orbiting the red-giant-branch star HD 112570 and the red-clump star HD 154391, based on the radial-velocity (RV) measurements from the Xinglong station and Okayama Astrophysical Observatory. Spectroscopic and asteroseismic analyses suggest that HD 112570 has a mass of 1.15 ± 0.12 M ☉, a radius of 9.85 ± 0.23 R ☉, a metallicity [Fe/H] of −0.46 ± 0.1, and logg of 2.47 ± 0.1. With the joint analysis of RV and Hipparcos-Gaia astrometry, we obtain a dynamical mass of Mp=3.42−0.84+1.4MJup , a period of P=2615−77+85 days, and a moderate eccentricity of e=0.20−0.14+0.16 for the Jovian planet HD 112570 b. For HD 154391, it has a mass of 2.07 ± 0.03 M ☉, a radius of 8.56 ± 0.05 R ☉, a metallicity [Fe/H] of 0.07 ± 0.1, and logg of 2.86 ± 0.1. The super-Jupiter HD 154391 b has a mass of Mp=9.1−1.9+2.8MJup , a period of P=5163−57+60 days, and an eccentricity of e=0.20−0.04+0.04 . We found that HD 154391 b has one of the longest orbital periods among those ever discovered orbiting evolved stars, which may provide a valuable case in our understanding of planetary formation at wider orbits. Moreover, while a mass gap at 4 M Jup seems to be present in the population of giant stars, there appear to be no significant differences in the distribution of metallicity among giant planets with masses above or below this threshold. Finally, the origin of the abnormal accumulation near 2 au for planets around large evolved stars (R ⋆ > 21 R ☉), remains unclear.

A NOVEL EXPERIMENTAL APPROACH TO STUDY DROP-PARTICLE COLLISIONS

Free drop-particle collisions occurring in air are experimentally produced by combining a stream of drops and a stream of particles, which results from the selective and ultra-fast hardening of another regular drop stream. The set-up offers the possibility to vary accurately the drop and particle diameter, the collision eccentricity, and the relative drop-particle velocity. First observations obtained with drop Weber numbers ranging from 30 to 300, drop Reynolds number between 390 and 4600, and with typical equilibrium contact angle of 70&amp;deg; evidence the existence of full deposition, separation, indicating possible bouncing events. For off-center separation, a liquid ligament forms between the particle and the outlying drop cap that fragments due to excessive stretching, a phenomenon similar to drop-drop collisions. In contrast, for head-on collisions and intermediate inertia, a lamella first forms, whose constrained recoil leads to liquid protuberance(s) that eventually pinch(es)-off. These outcomes can be distinguished using a bi-dimensional regime map built on the impact parameter and the drop Weber number. Despite remarkable similarities with binary drop collisions, important differences are observed especially for low and moderate eccentricities.

The California Legacy Survey. IV. Lonely, Poor, and Eccentric: A Comparison between Solitary and Neighborly Gas Giants

We compare systems with single giant planets to systems with multiple giant planets using a catalog of planets from a high-precision radial velocity survey of FGKM stars. Our comparison focuses on orbital properties, planet masses, and host-star properties. We use hierarchical methods to model the orbital eccentricity distributions of giant singles and giant multiples, and find that the distributions are distinct. The multiple giant planets typically have moderate eccentricities and their eccentricity distribution extends to e = 0.47 (90th percentile), while the single giant planets have a pileup of nearly circular orbits and a long tail that extends to e = 0.77. We determine that the stellar hosts of multiple giants are distinctly more metal rich than the hosts of solitary giants, with respective mean metallicities of 0.228 ± 0.027 versus 0.129 ± 0.019 dex. We measure the distinct occurrence distributions of single and multiple giants with respect to orbital separation, and find that single gas giants have a ∼2.3σ significant hot Jupiter (a < 0.06) pileup not seen among multigiant systems. We find that the median mass () of giants in multiples is nearly double that of single giants (1.71 M J versus 0.92 M J). We find that giant planets in the same system have correlated masses, analogous to the “peas in a pod” effect seen among less-massive planets.

Eccentric behaviour of GFRP-reinforced square columns with composite spiral ties

In this study, a new type of glass fiber reinforced polymer (GFRP) composite spiral ties was proposed to provide effective lateral restraint in square concrete columns. The GFRP-reinforced square columns with composite spiral ties were experimentally tested with both eccentric and concentric loadings. The effect of eccentricity-to-width ratio, tie spacing, and tie configuration was investigated. The test results indicated that the failure mode of the eccentric column showed more ductile failure characteristics than the concentric column. The compression-ductile failure observed at small and moderate eccentricity transformed to tension-controlled failure observed at high eccentricity with the increase of eccentricity. The ultimate load decreased significantly with increasing eccentricity, and a similar variation law also occurred for cracking loads. By applying GFRP composite spiral ties, a higher ultimate bearing capacity and cracking load could be attained, showing excellent lateral restraint performance. The eccentric behaviour of GFRP-reinforced square columns with composite spiral ties was evaluated by drawing experimental and theoretical normalized (Kn - Rn) diagrams.

3D global simulations of accretion onto gap-opening planets: implications for circumplanetary disc structures and accretion rates

ABSTRACT We perform a series of 3D simulations to study the accretion of giant planet embedded in protoplanetary discs (PPDs) over gap-opening time-scales. We find that the accretion mass flux mainly comes from the intermediate latitude above the disc mid-plane. The circumplanetary disc (CPD) for a super-thermal planet is rotation-supported up to ∼20–30 per cent of the planet Hill radius. While both mass inflow and outflow exists in the CPD mid-plane, the overall trend is an outflow that forms a meridional circulation with high-latitude inflows. We confirm the absence of accretion outburst from disc eccentricity excited by massive planets in our 3D simulations, contrary to the consensus of previous 2D simulations. This suggests the necessity of 3D simulations of accretion even for super-Jupiters. The accretion rates of planets measured in a steady state can be decomposed into the ‘geometric’ and ‘density depletion’ factors. Through an extensive parameter survey, we identify a power-law scaling for the geometric factor $\propto q_{\rm th}^{2/3}$ for super-thermal planets (qth being the thermal mass ratio), which transform to $\propto q_{\rm th}^{2}$ for less massive cases. The density depletion factor is limited by the disc accretion rate for mildly super-thermal planets and by gap-opening for highly super-thermal ones. Moderate planetary eccentricities can enhance the accretion rates by a factor of 2–3 by making the gap shallower, but it does not impact the flow geometry. We have applied our simulations results to accreting protoplanet system PDS 70 and can satisfactorily explain the accretion rate and CPD size in observations.

Chasing extreme planetary architectures

Context. Planet(s) in binaries are unique architectures for testing predictions of planetary formation and evolution theories in very hostile environments. Their presence in such a highly perturbed region poses a clear challenge from the early phase of planetesimals accretion to the dynamical evolution and stability through a very long period of time (several Gyrs in some case). Aims. The combination of radial velocity, speckle interferometry, high-contrast imaging and high-precision astrometry with interfer-ometry, offers a unique and unprecedented set of observable to push the exploration of the extreme planetary system HD 196885. By dissecting the physical and orbital properties of each component, we aim at shedding light on its global architecture and stability. Methods. We used the IRDIS dual-band imager of SPHERE at VLT, and the speckle interferometric camera HRCAM of SOAR, to acquire high-angular resolution images of HD 196885 AB between 2015 and 2020. Radial velocity observations started in 1983 with CORAVEL at OHP have been extended with a continuous monitoring with CORALIE at La Silla, and ELODIE and SOPHIE at OHP over almost 40 yr extending the radial velocity measurements HD 196885 A and resolving both the binary companion and the inner giant planet HD 196885 Ab. Finally, we took advantage of the exquisite astrometric precision of the dual-field mode of VLTI/GRAVITY (down to 30 µas) to monitor the relative position of HD 196885 A and B to search for the 3.6 yr astrometric wobble of the circumpri-mary planet Ab imprinted on the binary separation. Results. Our observations enable to accurately constrain the orbital properties of the binary HD 196885 AB, seen on an inclined and retrograde orbit (iAB = 120.43 deg) with a semi-major axis of 19.78 au, and an eccentricity of 0.417. The GRAVITY measurements confirm for the first time the nature of the inner planet HD 196885 Ab by rejecting all families of pole-on solutions in the stellar or brown dwarf masses. The most favored island of solutions is associated with a Jupiter-like planet (MAb = 3.39 MJup), with moderate eccentricity (eAaAb = 0.44), and inclination close to 143.04 deg. This results points toward a significant mutual inclination (Ф = 24.36 deg) between the orbital planes (relative to the star) of the binary companion B and the planet Ab. Our dynamical simulations indicate that the system is dynamically stable over time. Eccentricity and mutual inclination variations could be expected for moderate von Zipele Kozai Lidov cycles that may affect the inner planet.

Analytical Study of the Co-orbital Motion in the Circular Restricted Three-body Problem

In the restricted three-body problem (RTBP), if a small body and a planet stably orbit around a central star with almost exactly the same semimajor axis, and thus almost the same mean motion, this phenomenon is called the co-orbital motion, or equivalently, the 1:1 mean motion resonance. The classical expansion of the disturbing function is divergent when the semimajor axis ratio of the small body to the planet is close to unity. Thus, most of the previous studies on the co-orbital dynamics were carried out through numerical integrations or semi-analytical approaches. In this work, we construct an analytical averaged model for the co-orbital motion in the framework of the circular RTBP. This model is valid in the entire coorbital region except in the vicinity of the collision singularity. The results of the analytical averaged model are in good agreement with the numerical averaged model even for moderate eccentricities and inclinations. The analytical model can reproduce the tadpole, horseshoe and quasi-satellite orbits common in the planar problem. Furthermore, the asymmetry of 1:1 resonance and the compound orbits (Icarus 137:293–314) in the general spatial problem can also be obtained from the analytical model.

Analytical Solutions and a Clock for Orbital Progress Based on Symmetry of the Ellipse

Kepler’s discoveries were permitted by his remarkable insight to place the Sun at the focus of an elliptical planetary orbit. This coordinate system reduces a 2-dimensional orbit to a single spatial dimension. We consider an alternative coordinate system centered on the “image focus,” which is the symmetrical (mirror) counterpart of the “real focus” occupied by the Sun. Our analytical approach provides new purely geometric formulae and an exact relationship for the dynamic property of orbital time. In addition, considering the mirror symmetry of the ellipse leads to a simple approximation: the radial hand of an orbital clock rotates counterclockwise at a nearly steady angular velocity 2π/T about the “image focus,” where T is the orbital period. This approximation is a useful pedagogic tool and has good accuracy for orbits with low to moderate eccentricities, since the deviation from the exact result goes as eccentricity squared. Planetary comparisons are made. In particular, the angular speeds of Mercury and Jupiter are highly variable in the geocentric and heliocentric reference frames, but are nearly constant in the image focus reference frame. Our findings resolve whether the image focus is the location for observing uniform motion of an elliptical orbit, and pertain to their stability.

Planetary Orbit Eccentricity Trends (POET). I. The Eccentricity–Metallicity Trend for Small Planets Revealed by the LAMOST–Gaia–Kepler Sample

Orbital eccentricity is one of the basic planetary properties, whose distribution may shed light on the history of planet formation and evolution. Here, in a series of works on Planetary Orbit Eccentricity Trends (dubbed POET), we study the distribution of planetary eccentricities and their dependence on stellar/planetary properties. In this paper, the first work of the POET series, we investigate whether and how the eccentricities of small planets depend on stellar metallicities (e.g., [Fe/H]). Previous studies on giant planets have found a significant correlation between planetary eccentricities and their host metallicities. Nevertheless, whether such a correlation exists for small planets (e.g., super-Earths and sub-Neptunes) remains unclear. Here, benefiting from the large and homogeneous LAMOST–Gaia–Kepler sample, we characterize the eccentricity distributions of 244 (286) small planets in single (multiple) transiting systems with the TDR method. We confirm the eccentricity–metallicity trend whereby the eccentricities of single small planets increase with stellar metallicities. Interestingly, a similar trend between eccentricity and metallicity is also found in the radial velocity sample. We also found that the mutual inclination of multiple transiting systems increases with metallicity, which predicts a moderate eccentricity–metallicity rising trend. Our results of the correlation between eccentricity (inclination) and metallicity for small planets support the core accretion model for planet formation, and they could be footprints of self (and/or external) excitation processes during the history of planet formation and evolution.

Detecting accelerating eccentric binaries in the LISA band

Many gravitational wave (GW) sources in the LISA band are expected to have non-negligible eccentricity. Furthermore, many of them can undergo acceleration because they reside in the presence of a tertiary. Here we develop analytical and numerical methods to quantify how the compact binary's eccentricity enhances the detection of its peculiar acceleration. We show that the general relativistic precession pattern can disentangle the binary's acceleration-induced frequency shift from the chirp-mass-induced frequency shift in GW template fitting, thus relaxing the signal-to-noise ratio requirement for distinguishing the acceleration by a factor of $10\sim100$. Moreover, by adopting the GW templates of the accelerating eccentric compact binaries, we can enhance the acceleration measurement accuracy by a factor of $\sim100$, compared to the zero-eccentricity case, and detect the source's acceleration even if it does not change during the observational time. For example, a stellar-mass binary black hole (BBH) with moderate eccentricity in the LISA band yields an error of the acceleration measurement $\sim10^{-7}m\cdot s^{-2}$ for $\rm{SNR}=20$ and observational time of $4$ yrs. In this example, we can measure the BBHs' peculiar acceleration even when it is $\sim1\rm pc$ away from a $4\times 10^{6}\rm M_{\odot}$ SMBH. Our results highlight the importance of eccentricity to the LISA-band sources and show the necessity of developing GW templates for accelerating eccentric compact binaries.

Experimental investigation of GFRP‐reinforced concrete columns made with waste aggregates under concentric and eccentric loads

AbstractNowadays, reducing the waste and recycled material resources in nature and environmental protection, as well as reducing the use of natural resources, has gained the attention of engineers and researchers. One of the ways to reach this goal is to use waste and recycled materials in new concrete members' construction. Additionally, using glass fiber‐reinforced polymer (GFRP) rebars has gained high consideration owing to their advantages such as high tensile strength and corrosion resistance. Therefore, this study aims to measure the influence of recycled coarse aggregates (RCA) on the structural performance of reinforced concrete (RC) columns reinforced by GFRP rebars under concentric and eccentric loading conditions. A total of 24 RC columns were cast and subjected to concentric and eccentric loads with different eccentricity ratios (e/h):0 (no eccentricity), 0.25 (moderate eccentricity), and e/h = 0.5 (high eccentricity). A total of 18 columns were strengthened with longitudinal GFRP rebars, and six specimens were considered control samples reinforced by steel rebars. RCA was used at two contents of 0% and 100% in terms of weight as a substitute for natural coarse aggregates (NCA). In addition, to measure the influence of transverse reinforcement, three different spacings were considered: 60, 120, and 180 mm. Evaluation of axial behavior, the strain of rebars and concrete, and the ductility were the main aims of this study. Moreover, a comparison between the experimental results and existing standards was carried out. Findings revealed the adequate axial resistance of specimens when RCA was used. Therefore, RCA incorporation improved the axial resistance of GFRP‐RC columns by about 25% and 35% when the stirrup spacing declined by 60 and 120 mm, respectively in comparison with the same specimens made with NCA. However, the influence of RCA on the RC columns' axial behavior was declined by raising the eccentricity distance.

Apsidal alignment and anti-alignment of planets in mean-motion resonance: disc-driven migration and eccentricity driving

ABSTRACT Planets migrating in their natal discs can be captured into mean-motion resonance (MMR), in which the planets’ periods are related by integer ratios. Recent observations indicate that planets in MMR can be either apsidally aligned or anti-aligned. How these different configurations arise is unclear. In this paper, we study the MMR capture process of migrating planets, focusing on the property of the apsidal angles of the captured planets. We show that the standard picture of MMR capture, in which the planets undergo convergent migration and experience eccentricity damping due to planet–disc interactions, always leads to apsidal anti-alignment of the captured planets. However, when the planets experience eccentricity driving from the disc, apsidally aligned configuration in MMR can be produced. In this configuration, both planets’ resonance angles circulate, but a ‘mixed’ resonance angle librates and traps the planets near the nominal resonance location. The MMR capture process in the presence of disc eccentricity driving is generally complex and irregular, and can lead to various outcomes, including apsidal alignment and anti-alignment, as well as the disruption of the resonance. We suggest that the two resonant planets in the K2-19 system, with their moderate eccentricities and aligned apsides, have experienced eccentricity driving from their natal disc in the past.

Systematic bias on parametrized tests of general relativity due to neglect of orbital eccentricity

Gravitational-wave observations provide a unique opportunity to test general relativity (GR) in the strong-field and highly dynamical regime of the theory. Parametrized tests of GR are one well-known approach for quantifying violations of GR. This approach constrains deviations in the coefficients of the post-Newtonian phasing formula, which describes the gravitational-wave phase evolution of a compact binary as it inspirals. Current bounds from this test using LIGO/Virgo observations assume that binaries are circularized by the time they enter the detector frequency band. Here, we investigate the impact of residual binary eccentricity on the parametrized tests. We study the systematic biases in the parameter bounds when a phasing based on the circular orbit assumption is employed for a system that has some small residual eccentricity. We find that a systematic bias (for example, on the leading Newtonian deformation parameter) becomes comparable to the statistical errors for even moderate eccentricities of $\sim 0.04$ at $10$ Hz in LIGO/Virgo band for binary black holes, and $\sim 0.008$ for binary neutron stars. This happens at even lower values of orbital eccentricity in the frequency band of third-generation (3G) detectors like Cosmic Explorer ($\sim 0.005$ at $10$ Hz for binary black holes and $\sim 0.002$ for binary neutron stars). These results demonstrate that incorporating physical effects like eccentricity in waveform models is important for accurately extracting science results from future detectors.

The Traspena meteorite: heliocentric orbit, atmospheric trajectory, strewn field, and petrography of a new L5 ordinary chondrite

ABSTRACTThe Traspena meteorite fell on 2021 January 18 about 20 km south-east of the city of Lugo (Galiza, Spain), shortly after a huge and bright fireball crossed the sky for 4.84 s. Astrometric measurements obtained from the fireball cameras of the Universidade de Santiago de Compostela (USC) as well as from many casual videos were used to determine the atmospheric trajectory of this meteoroid which penetrated the atmosphere and generated sound waves that were detected at three seismic stations. The original meteoroid had a diameter of about 1.15 m and a mass around 2620 kg. It impacted the Earth’s atmosphere with a steep entry angle of about 76${_{.}^{\circ}}$7 from a height of 75.10 km until fading away at 15.75 km with a velocity of 2.38 km s−1. Before the impact, this small asteroid was orbiting the Sun with a semimajor axis of 1.125 au, a moderate eccentricity of 0.386, and a low inclination of 4${_{.}^{\circ}}$55. A weak evidence of dynamic link with the PHA (Potential Hazardous Asteroid) Minos was investigated. During the atmospheric entry, two major fragmentation events occurred between heights of 35 and 29 km at aerodynamic pressures between 1 and 5 MPa. The strewn field was computed after calculating the individual dark flights of the main body along with two smaller fragments. Fortunately, 2 month after the superbolide, a 527-g meteorite was found. It was examined using several geochemical and petrographic analyses which allowed us to classify it as a moderately shocked (S3) L5 ordinary chondrite with a bulk density of 3.25 g cm−3.