Inspiral Research Articles

Research on Messaging Applications as Mediators to Enhance Design Creativity in Industrial Design Students in China

Background and Aim: In globalization, creativity emerges as a pivotal factor in bolstering the competitiveness of nations and individuals. Therefore, fostering students' creativity becomes a crucial goal of education and a key driver for societal development and innovation. This study, with its potential to determine the factors that affect the design creativity of industrial design students through messaging applications, holds significant promise. The research framework includes variables such as design creativity (DC), knowledge sharing (KS), cooperative learning (CL), inspiration (IN), creative self-efficacy (CS), and the use of messaging applications (UMA). By exploring the influence of educational methods on creativity development through the analysis of students' creative generation process in messaging applications, we aim to provide new perspectives and tools that could profoundly impact creativity and educational research. Materials and Methods: In this research, we meticulously collected 467 valid questionnaires from colleges and universities in Sichuan Province, China, employing rigorous quantitative methods and questionnaire surveys. To ensure the utmost accuracy of the questionnaire data, we conducted a confirmatory factor analysis (CFA) to test the relationship between the observed variables and the potential variables. Subsequently, we employed the structural equation model (SEM) to test the research hypothesis comprehensively. Applying these two analytical techniques underscores the scientific rigor of our research methods and the robustness of our results. Result: The results of data analysis show that the use of message application, knowledge sharing, cooperative learning, inspiration, and creative self-efficacy significantly affect design creativity. Using message application as an intermediary variable improves industrial design students' knowledge-sharing and creative self-efficacy, thus enhancing their design creativity. However, the intermediary role of message application between inspiration, collaborative learning, and design creativity is not significant. This finding contrasts with the results of pilot tests, reflecting the differences in educational strategies implemented by different educators in influencing students' interaction and inspiration in collaborative learning. Conclusion: Studying the use of message applications to enhance creativity can promote educational equity and social interaction and stimulate interdisciplinary learning and collective wisdom. At the same time, cultivate students' innovative skills and lifelong learning and innovation ability. The research results provide educators with insights into how industrial design students can use new applications more effectively to improve their design creativity and confirm the effectiveness of students' creativity self-assessment. Therefore, in educational practice, the design creativity self-assessment scale can be used to evaluate students' design works. In addition, this study can be used as a reference for teaching and creativity research in other art disciplines.

How geomagnetic storms affect the loss of Starlink satellites in February 2022?

Abstract On February 8, 2022, approximately 40 of the 49 Starlink satellites were reported to have lost altitude, leading to atmospheric re-entry. SpaceX reported that the orbital decay on Starlink satellites was considered to be linked to a geomagnetic storm that was initiated on February 3, 2022. We attempted to analyze the cause of orbital decay by sampling all Starlink satellites registered in the SpaceTrack database and then tracing some space weather parameters and species density variations in the thermospheric layer. We employed the solar wind and IMF Bz to see their impact on geomagnetic activity. Moreover, we also analyzed the electric field Ey, Dst, AE, and Ap indices in addition to the solar EUV flux to see their impact on the Starlink satellite environment. We discovered three geomagnetic substorms during the analysis period: two successive substorms on February 4 and 5, and one additional substorm on February 10. We inferred that magnetic substroms significantly affected species densities, mainly O, O2, and N2, around some Starlink satellites, leading to an increase in atmospheric drag. There was a time delay between the substorms and orbital decay on Starlink satellites. However, some Starlink satellites were not affected by geomagnetic substorms due to insignificant changes in their environment. The reason for this is that, despite having lower altitudes, all decaying Starlinks were located in the midnight-dawn sector, in which the drift of ionospheric currents was predominantly driven by westward electrojets. On the other hand, all non-decaying Starlink satellites that had higher altitudes resided in the dusk–midnight sector of magnetic local time, where the impact of substorms insignificantly affected their altitudes. Graphical Abstract

New TESS Secondary Eclipses Confirm Orbital Decay of Kepler-1658b

Abstract I present new primary and secondary eclipse timing measurements for the hot Jupiter Kepler-1658b from TESS Sectors 74, 75, 81, and 82. Joint analysis of these measurements with historical Kepler data and radial velocity observations confirms orbital decay with rate P ˙ = ( − 3.423 ± 0.458 ) × 1 0 − 4 s day−1. The detection of secondary eclipses in TESS data provides independent confirmation of decay over precession models (BIC = − 364.3, χ ν 2 = 1.51 ), yielding a stellar tidal quality factor Q ⋆ ′ = ( − 2.27 ± 0.85 ) × 1 0 4 . These measurements strengthen the case for rapid tidal inspiral in this evolved system.

Planet-star interactions with precise transit timing

Context. Giant exoplanets on 1-3 day orbits, known as ultra-hot Jupiters, induce detectable tides in their host stars. The energy of those tides dissipates at a rate related to the properties of the stellar interior. At the same time, a planet loses its orbital angular momentum and spirals into the host star. The decrease in the orbital period is empirically accessible with precise transit timing and can be used to probe planet-star tidal interactions. Aims. Statistical studies show that stars of GK spectral types, with masses below 1.1 M⊙, are depleted in hot Jupiters. This finding is evidence of tidal orbital decay during the main-sequence lifetime. Theoretical considerations show that in some configurations the tidal energy dissipation can be boosted by non-linear effects in dynamical tides, which are wave-like responses to tidal forcing. To probe the regime of these dynamical tides in GK stars, we searched for orbital period shortening for six selected hot Jupiters in systems with 0.8–1 M⊙ host stars: HATS-18, HIP 65A, TrES-3, WASP-19, WASP-43, and WASP-173A. Methods. For the hot Jupiters in our sample, we analysed transit timing datasets based on mid-transit points homogeneously determined from observations performed with the Transiting Exoplanet Survey Satellite and high-quality data available in the literature. For the TrES-3 system, we also used new transit light curves we acquired with ground-based telescopes. We searched mid-transit times for shortening of orbital periods by statistically testing quadratic transit ephemerides. Theoretical predictions on the dissipation rate for dynamical tides were calculated under the regimes of internal gravity waves (IGWs) undergoing wave breaking (WB) in stellar centres and weak non-linear (WNL) wave-wave interactions in radiative layers. Stellar parameters of the host stars, such as mass and age, which were used in those computations, were homogeneously redetermined using evolutionary models with the Bayesian inference. Results. We found that transit times follow the refined linear ephemerides for all ultra-hot Jupiters of our sample. The non-detection of orbital decay allowed us to place lower constraints on the tidal dissipation rates in those planet-star systems. In three systems, HATS-18, WASP-19, and WASP-43, we reject a scenario with total dissipation of IGWs. We conclude that their giant planets are not massive enough to induce WB. Our observational constraints for HIP 65A, TrES-3, and WASP-173A are too weak to probe the WB regime. Calculations show that WB is not expected in the former two, leaving the WASP-173A system as a promising target for further transit timing observations. The WNL dissipation was tested in the WASP-19 and WASP-43 systems, showing that the theoretical dissipation rates are overestimated by at least one order of magnitude. For the remaining systems, decades or even centuries of transit timing measurements are needed to probe the WNL regime entirely. Among them, TrES-3 and WASP-173A have the predicted WNL dissipation rates that coincide with the values obtained from gyrochronology. Conclusions. Tidal dissipation in the GK stars of our sample is not boosted by WB in their radiative cores, preventing their giant planets from rapid orbital decay. Weakly non-linear tidal dissipation could drive orbital shrinkage and stellar spin-up on gigayear timescales. Although our first results suggest that theory might overestimate the dissipation rate and some fine-tuning would be needed for at least a fraction of planet-star configurations, some predictions coincide intriguingly with the gyrochronological estimates. We identify the WASP-173A system as a promising candidate for exploring this problem in the shortest possible time of the coming decades.

Optimal drag-based collision avoidance: Balancing miss distance and orbital decay

The increasing number of objects in Low Earth Orbit makes active collision avoidance imperative for satellites operating in this region. For satellites non equipped with propulsion systems, the collision risk can be mitigated by exploiting the active modulation of aerodynamic forces through the ballistic coefficient. This article proposes a novel and high-fidelity optimal control approach for collision avoidance via aerodynamic drag modulation for an unpropelled SmallSat. Central to this approach is a cost function that jointly maximizes the miss distance while minimizing orbital decay during the maneuver. Moreover, the proposed approach has been rigorously tested through its application to the real-world scenario of the SOURCE satellite, slated for launch in 2025. For the satellite under investigation and a maneuver altitude of 350km, an in-track separation distance of around 22km can be accomplished within a warning time of 24h, which is large enough to conclude that the collision was successfully avoided. As a downside, however, this results in an additional loss in the semi-major axis of 165m and thus a reduced lifetime of the satellite. This balance between separation distance and additional loss in altitude can be flexibly adjusted by the user, which is demonstrated extensively in the article by means of a parameter study. Compared to the widespread use of chemical propulsion systems, this strategy naturally demands longer warning times due to the significantly lower available forces, and also radial offsets to the potential collision object cannot be in this case. Nevertheless, it offers a very promising alternative for active collision avoidance, especially for low-altitude applications.

Structure formation with primordial black holes: collisional dynamics, binaries, and gravitational waves

Primordial black holes (PBHs) could compose the dark matter content of the Universe. We present the first simulations of cosmological structure formation with PBH dark matter that consistently include collisional few-body effects, post-Newtonian orbit corrections, orbital decay due to gravitational wave emission, and black-hole mergers. We carefully construct initial conditions by considering the evolution during radiation domination as well as early-forming binary systems. We identify numerous dynamical effects due to the collisional nature of PBH dark matter, including evolution of the internal structures of PBH halos and the formation of a hot component of PBHs. We also study the properties of the emergent population of PBH binary systems, distinguishing those that form at primordial times from those that form during the nonlinear structure formation process. These results will be crucial to sharpen constraints on the PBH scenario derived from observational constraints on the gravitational wave background. Even under conservative assumptions, the gravitational radiation emitted over the course of the simulation appears to exceed current limits from ground-based experiments, but this depends on the evolution of the gravitational wave spectrum and PBH merger rate toward lower redshifts.

Orbital Lifetime Estimation of Rocket Bodies in Eccentric Low Earth, Low Inclination Orbits

The dense population of Low Earth Orbit (LEO) due to frequent launches necessitates precise knowledge of the orbital lifetime of rocket bodies in this region. This study focuses on estimating the orbital lifetime of rocket bodies in eccentric, low-inclination LEO. Using the open-source software General Mission Analysis Tool (GMAT), the orbital lifetimes of rocket bodies with masses of 1000 kg, 1200 kg, and 1400 kg were calculated for altitudes ranging from 250 km to 500 km and inclinations of 0˚, 10˚, and 20˚. The orbital lifetimes of the defunct rocket bodies ranged from 3 to 832 days. GMAT-derived orbital lifetimes were compared with those obtained using Systems Tool Kit (STK). A subsequent 2D interpolation code was developed to interpolate the lifetime for a user-provided configuration of mass and orbital altitude. The Python code interpolated the orbital lifetimes for the given configurations with a maximum error of 5% compared to the GMAT-simulated lifetime values. This approach provides essential data for assessing post-mission disposal plans for rocket bodies and ensuring alignment with the Inter-Agency Space Debris Coordination Committee (IADC) 25-year guideline. Key findings reveal that the orbital lifetime of a rocket body increases with inclination. Additionally, it was observed that the orbital lifetime increases with mass due to slower orbital decay.

A low earth orbit satellite descent strategy

The object of the article is the method of descending a satellite from low Earth orbit (LEO) at the end of its service lifetime for its disposal. The main problem is to ensure a safe and cost-effective disposal of the satellite while minimizing risks to the environment and other objects in orbit. Based on the method, calculations were made for lowering the orbit and directing the satellite to a remote area of the Earth’s ocean. The calculations included braking pulses, fuel consumption, descent time to the burial orbit, and the time for natural descent before reaching the Earth's surface. The descent process is divided into three stages: active descent using low-thrust engines (LTE), passive descent due to natural braking in the out-of-atmosphere part, and fall through the dense atmosphere. Dependency graphs were provided to illustrate orbit altitude, satellite speed, reentry angle changes, and flight range over time. The findings revealed that combining active orbital maneuvers with passive orbital decay optimizes the deorbiting procedure by minimizing fuel requirements and operational complexity. The proposed strategy ensures the satellite-controlled re-entry and safe disposal, significantly reducing the risks of collisions and environmental impact. The results solved the problem by defining a staged satellite descent process. Duration were computed for active descent with braking impulses for uniform altitude reduction and passive descent due to atmospheric drag. The trajectory and duration of fall in atmosphere. The process ensures controlled re-entry and safe disposal. This method is suitable for satellite operators and space agencies handling LEO missions

Hints of a close outer companion to the ultra-hot Jupiter TOI-2109 b

Hot Jupiters (HJs) with close-by planetary companions are rare, with only a handful of them having been discovered so far. This could be due to their suggested dynamical histories, which lead to the possible ejection of other planets. TOI-2109\,b is special in this regard because it is the HJ with the closest relative separation from its host star, being separated by less than 2.3 stellar radii. Unexpectedly, transit timing measurements from recently obtained CHEOPS observations show low-amplitude transit-timing variations (TTVs). We aim to search for signs of orbital decay and to characterise the apparent TTVs in an attempt to gain information about a possible companion. We fitted the newly obtained CHEOPS light curves using TLCM and extracted the resulting mid-transit timings. Successively, we used these measurements in combination with TESS and archival photometric data and radial velocity (RV) data to estimate the rate of tidal orbital decay of TOI-2109\,b, and also to characterise the TTVs using the N-body code TRADES and the photo-dynamical approach of PyTTV We find tentative evidence at $3 for orbital decay in the TOI-2109 system when we correct the mid-transit timings using the best-fitting sinusoidal model of the TTVs. We do not detect additional transits in the available photometric data, but find evidence supporting the authenticity of the apparent TTVs indicating a close-by, outer companion with $P_ c > 1.125\,$d. Due to the fast rotation of the star, the new planetary candidate cannot be detected in the available RV measurements, and its parameters can only be loosely constrained by our joint TTV and RV modelling. TOI-2109 could join a small group of rare HJ systems that host close-by planetary companions, only one of which (WASP-47\,b) has an outer companion. More high-precision photometric measurements are necessary to confirm the existence of this planetary companion.

Eccentricity effects on the supermassive black hole gravitational wave background

We studied how eccentricity affects the gravitational wave (GW) spectrum from supermassive black hole (SMBH) binaries. We developed a fast and accurate semi-analytic method for computing the GW spectra, the distribution for the spectral fluctuations and the correlations between different frequencies. As GW emission circularizes binaries, the suppression of the signal strength due to eccentricity is relevant for signals from wider binaries emitting at lower frequencies. Such a feature is present in the signal observed at pulsar timing arrays. We found that when orbital decay of the SMBH binaries is driven by GWs only, the shape of the observed signal preferred highly eccentric binaries ⟨e⟩2nHz =0.830.04−0.05. However, when environmental effects were included, the initial eccentricity could be significantly lowered, yet the scenario with purely circular binaries was still mildly disfavored.

Estimates of Spherical Satellite Drag Coefficients in the Upper Thermosphere During Different Geomagnetic Conditions

AbstractSatellite drag coefficients are crucial for determining the neutral mass densities that affect spacecraft operations in the thermosphere. Many studies typically utilize a constant drag coefficient of 2.2 to calculate the neutral density. However, due to the variability of space environment, uncertainties in the drag coefficient can lead to significant systematic discrepancies in neutral density measurements. Satellite drag coefficient may fluctuate in the thermosphere under various geomagnetic activities and altitudes. For the first time, we calculate the spherical satellite drag coefficient using data from the “Orbital Atmospheric Density Detection Experimental Satellite,” referred to as the QX satellite. Our findings reveal that the drag coefficient can be estimated by thermospheric temperature and density, which are dependent on geomagnetic activity and altitude. At an altitude of ∼510 km, drag coefficients are adjusted to around 2.425, instead of the constant value of 2.2. Furthermore, the drag coefficient may decrease due to the significant influence of increasing geomagnetic activity, such as geomagnetic storms, on thermospheric density and temperature. These estimates of the drag coefficient can also be used to reduce discrepancies when deducing the ballistic coefficient. Consequently, using the estimated drag coefficient can accurately determine the QX‐derived neutral density, which agrees well with the density from Swarm‐B satellite.

Spin–Orbit Alignment of Early-type Astrometric Binaries and the Origin of Slow Rotators

The spin–orbit alignment of binary stars traces their formation and accretion history. Previous studies of spin–orbit alignment have been limited to small samples, slowly rotating solar-type stars, and/or wide visual binaries that not surprisingly manifest random spin–orbit orientations. We analyze 917 Gaia astrometric binaries across periods P = 100–3000 days (a = 0.5–5 au) that have B8-F1 IV/V primaries (M 1 = 1.5–3 M ⊙) and measured projected rotational velocities v sin i. The primary stars in face-on orbits exhibit substantially smaller v sin i compared to those in edge-on orbits at the 6σ level, demonstrating significant spin–orbit alignment. The primaries in our astrometric binaries are rotating more slowly than their single-star or wide-binary counterparts and therefore comprise the slow-rotator population in the observed bimodal rotational velocity distribution of early-type stars. We discuss formation models of close binaries where some of the disk angular momentum is transferred to the orbit and/or secondary spin, quenching angular momentum flow to the primary spin. The primaries in astrometric binaries with small mass ratios q = M 2/M 1 < 0.3 possess even smaller v sin i, consistent with model predictions. Meanwhile, astrometric binaries with large eccentricities e > 0.4 do not display spin–orbit alignment or spin reduction. Using a Monte Carlo technique, we measure a spin–orbit alignment fraction of F align = 75% ± 5% and an average spin reduction factor of 〈S align〉 = 0.43 ± 0.04. We conclude that 75% of close A-type binaries likely experienced circumbinary disk accretion and probably formed via disk fragmentation and inward disk migration. The remaining 25%, mostly those with e > 0.4, likely formed via core fragmentation and orbital decay via dynamical friction.

Ticking away: The long-term X-ray timing and spectral evolution of eRO-QPE2

Quasi-periodic eruptions (QPEs) are repeated X-ray flares from galactic nuclei that recur every few hours to days, depending on the source. Despite some diversity in the recurrence and amplitude of eruptions, their striking regularity has motivated theorists to associate QPEs with orbital systems. Among the known QPE sources, eRO-QPE2 has shown the most regular flare timing and luminosity since its discovery. We report here on its long-term evolution over 3.3 yr from discovery and find that: i) the average QPE recurrence time per epoch has decreased over time, albeit not at a uniform rate; ii) the distinct alternation between consecutive long and short recurrence times found at discovery has not been significant since; iii) the spectral properties, namely flux and temperature of both eruptions and quiescence components, have remained remarkably consistent within uncertainties. We attempted to interpret these results as orbital period and eccentricity decay coupled with orbital and disk precession. However, since gaps between observations are too long, we are not able to distinguish between an evolution dominated by just a decreasing trend, or by large modulations (e.g. due to the precession frequencies at play). In the former case, the observed period decrease is roughly consistent with that of a star losing orbital energy due to hydrodynamic gas drag from disk collisions, although the related eccentricity decay is too fast and additional modulations have to contribute too. In the latter case, no conclusive remarks are possible on the orbital evolution and the nature of the orbiter due to the many effects at play. However, these two cases come with distinctive predictions for future X-ray data: in the case of a decreasing trend, we expect all future observations to show a shorter recurrence time than the latest epoch, while in the case of large-amplitude modulations we expect some future observations to be found with a larger recurrence, hence an apparent temporary period increase.

Probing the Possible Causes of the Transit Timing Variation for TrES-2b in the TESS Era

Nowadays, transit timing variations (TTVs) are proving to be a very valuable tool in exoplanetary science to detect exoplanets by observing variations in transit times. To study the TTV of the hot Jupiter TrES-2b, we have combined 64 high-quality transit light curves from all seven sectors of NASA's Transiting Exoplanet Survey Satellite along with 60 best-quality light curves from the ground-based facility Exoplanet Transit Database and 106 midtransit times from the previous works. From the precise transit timing analysis, we have observed a significant improvement in the orbital ephemerides, but we did not detect any short-period TTVs that might result from an additional body. The inability to detect short-term TTVs further motivates us to investigate long-term TTVs, which might be caused by orbital decay, apsidal precession, the Applegate mechanism, and the Rømer effect, and the orbital decay appeared to be a better explanation for the observed TTV with ΔBIC = 4.32. The orbital period of the hot Jupiter TrES-2b appears to be shrinking at a rate of ∼–5.58 ± 1.81 ms yr−1. Assuming this decay is primarily caused by tidal dissipation within the host star, we have subsequently calculated the stellar tidal quality factor value to be ∼9.9 × 103, which is 2–3 orders of magnitude smaller than the theoretically predicted values for other hot-Jupiter systems, and its low value indicates more efficient tidal dissipation within the host star. Additional precise photometric and radial velocity observations are required to pinpoint the cause of the change in the orbital period.

Decay time estimate for LEO spacecraft

The growing concerns posed by orbital debris represent a serious threat to the future of space operations in low Earth orbit. With the goal of limiting the formation of new debris, space agencies are proposing international guidelines that satellites should be able to deorbiting within 25 years of the end of their operational life. Orbital decay is typically caused by atmospheric drag, so estimating the decay time of a satellite subject to drag is critical to assessing whether the guidelines are met. However, such estimate is a very challenging task because of the difficulty of accurately modeling atmospheric properties and because of the coupling of orbital dynamics with spacecraft attitude. In this paper, a simplified algorithm based on the King-Hele formulation is proposed to rapidly estimate the decay time of an orbiting satellite without imposing any assumptions on the spacecraft’s nominal size, mass, geometry or attitude. The algorithm accounts for the effect of solar activity level variations on atmospheric properties and drag coefficient through an iterative procedure and can be applied to any object in orbit. Numerical tests show that the predictions in terms of decay times are very accurate for satellites that are quite different in size and geometry, including the presence of an aerodynamic drag augmentation system such as a drag sail.

Drag sail attitude tracking via nonlinear control

A drag sail is a propellantless device suitable for passive deorbiting of satellites after their end-of-life. It exploits atmospheric drag to gradually reduce the kinetic energy of the decommissioned satellite and cause it to lose altitude over time. It is well known that the braking effect of the atmosphere is greater the surface exposed to the flow of the atmospheric particles relative to the satellite. For this reason, a drag sail is essentially a large and lightweight membrane, which is deployed by the satellite when it is to begin orbital decay. For given environmental/initial conditions and inertial characteristics of the deployed system, the braking effect of a drag sail is more intense if its perpendicular axis is constantly aligned with the direction of the relative particle flow. For this purpose, a sliding mode control strategy is adopted. The reference to follow is obtained by propagating the spacecraft orbital dynamics along with its attitude dynamics. Various orbital perturbations and the disturbance torque due to atmospheric drag are implemented in the numerical code to verify the robustness of the proposed control law. It is also assumed that the spacecraft control torque vector is bounded in magnitude and always belongs to the plane of the braking device. The results show that the proposed strategy is effective in accurately tracking the reference attitude and that it is robust, being able to track a reference that varies unpredictably due to both orbital and attitude perturbations.

Listening to dark sirens from gravitational waves : Combined effects of fifth force, ultralight particle radiation, and eccentricity

We analyse the orbital period decay in compact binary systems influenced by a fifth force and ultralight particle radiation, considering a general eccentric Keplerian orbit. The analysis provides constraints on the axion decay constant when orbital period decay involves axionic fifth force and axion radiation. The bound on axion coupling improves by an order of magnitude for high eccentricity binaries like the Hulse–Taylor binary. These bounds become stronger when considering both axion mediation and radiation. We also derive constraints on the strengths of the fifth force and radiation from GW170817 by measuring the Chirp mass, which depends on initial eccentricity. The coalescence time increases with higher initial eccentricity compared to the gravity-only scenario, highlighting the importance of accurately selecting initial eccentricity for setting bounds on fifth force searches in precision gravitational wave detection. Additionally, we provide model-independent estimates for dark matter capture by a binary system. The derived constraints can be further strengthened with the use of second and third generation gravitational wave detectors.

New Transit Timing Observations of WASP-12b from TESS Sectors 71 and 72

I present new transit and occultation timing measurements for the hot Jupiter WASP-12b using data from TESS Sectors 71 and 72, observed in 2023. Using full-phase curve fitting for the first time, I precisely locate both transits and occultations. I report 34 new transit times and sector-specific occultation times, updating the orbital decay rate to −26.310 ± 0.901 ms yr−1. My analysis strongly favors the orbital decay model over constant period and apsidal precession models.

Revisiting WASP-19b’s Orbital Evolution: New TESS Data and Apsidal Precession Analysis

Due to the ongoing debate of whether WASP19b is experiencing orbital decay or apsidal precession, I reexamine the orbital evolution of the hot Jupiter WASP-19b using new TESS data from sectors 09, 36, 62, and 63. My comprehensive analysis of transit and occultation timing variations compares models of constant period, orbital decay, and apsidal precession. Results show no significant preference between orbital decay and apsidal precession models. I find a period change rate of −1.40 ± 0.54 ms yr−1, slower than some previous studies but consistent with others. My apsidal precession analysis yields an eccentricity of 0.00178 and a precession rate of 0.036 deg day−1, differing from recent literature. These findings underscore the complexity of WASP-19b’s orbital dynamics and the need for continued long-term monitoring.

Searching for tidal orbital decay in hot Jupiters

ABSTRACT We study transits of several ‘hot Jupiter’ systems, including WASP-12 b, WASP-43 b, WASP-103 b, HAT-P-23 b, KELT-16 b, WD 1856+534 b, and WTS-2 b, with the goal of detecting tidal orbital decay and extending the baselines of transit times. We find no evidence of orbital decay in any of the observed systems except for that of the extensively studied WASP-12 b. Although the orbit of WASP-12 b is unequivocally decaying, we find no evidence for acceleration of said orbital decay, with measured $\ddot{P} = (-7 \pm 8) \times 10^{-14} \, \rm s^{-1}$, against the expected acceleration decay of $\ddot{P} \approx -10^{-23} \, \rm s^{-1}$. In the case of WD 1856+534 b, there is a tentative detection of orbital growth with $\dot{P} = (5.0 \pm 1.5) \times 10^{-10}$. While statistically significant, we err on the side of caution and wait for longer follow-up observations to consider the measured $\dot{P}$ real. For most systems, we provide a 95 per cent confidence lower limit on the tidal quality factor, $Q_\star ^{\prime }$. The possibility of detecting orbital decay in hot Jupiters via long-term radial velocity (RV) measurements is also explored. We find that ${\sim} 1 \rm \, m \, s^{-1}$ precision in RVs will be required to detect orbital decay of WASP-12 b with only 3 yr of observations. Currently available RV measurements and precision are unable to detect orbital decay in any of the systems studied here.