Shape Model and Rotation Acceleration of (1685) Toro and (85989) 1999 JD6 from Optical Observations

Tian, Jun; Zhao, Haibin; Li, Bin

doi:10.1088/1674-4527/ac977d

Cited by 4 publications

(7 citation statements)

References 50 publications

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“…This is a tighter constraint than was found by Marshall (2017), but it does not yet prove the YORP signal. The reason for the difference between our results and that in Tian et al (2022) eludes us. The best we could have done is to double-check our solution, which is compatible for the YORP nondetection with that of Marshall (2017).…”

Section: (85989) 1999 Jd6contrasting

confidence: 94%

“…We continue this tradition. For brevity, we recall Table 3 of Tian et al (2022), who listed the relevant last YORP detections. Our work represents two modifications: (i) an extension by two new detections for (2100) Ra-Shalom and (138852) 2000 WN10, but (ii) also one retraction, at least as far as the situation stands now, namely a nondetection of YORP for (85989) 1999 JD6.…”

Section: Discussionmentioning

confidence: 99%

“…Finally, (2100) Ra-Shalom represents a difficult analysis in which the spin-axis precession is detected for the first time together with the YORP effect on a body with the lowest rotation frequency so far. Additionally, we analyzed available data for asteroid (85989) 1999 JD6, for which the YORP effect has previously been reported by Tian et al (2022). However, the addition of new observations to the data set of this object shows that the YORP effect has not yet been detected at a statistically significant level.…”

Section: Introductionmentioning

confidence: 94%

“…Recently, Tian et al (2022) analyzed a larger set of photometric observations taken between 2000 and 2020 and claimed to have detected the YORP effect with υ = (2.4 ± 0.3) × 10 −8 rad d −2 . However, the results we presented in Sect.…”

Section: (85989) 1999 Jd6mentioning

confidence: 99%

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Secular change in the spin states of asteroids due to radiation and gravitation torques

Ďurech,

Vokrouhlický,

Pravec

et al. 2024

A&A

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The rotation state of small asteroids is affected in the long term by perturbing torques of gravitational and radiative origin (the YORP effect). The former can be detected by a change in the spin-axis orientation in the inertial space; the latter manifests itself by a quadratic increase in the rotation phase. Direct observational evidence of the YORP effect is the primary goal of our work. This includes both the YORP detection for new objects and an improvement in the accuracy of previously known detections. We carried out photometric observations of five near-Earth asteroids: (1862) Apollo, (2100) Ra-Shalom, (85989) 1999 JD6, (138852) 2000 WN10, and (161989) Cacus. Then we applied the light-curve inversion method to all available data to determine the spin state and a convex shape model for each of the five studied asteroids. The YORP effect was modeled as a linear change of the rotation frequency $ In the case of (2100) Ra-Shalom, the analysis required that the spin-axis precession due to the solar gravitational torque also be included. We obtained two new detections of the YORP effect: (i) $ for (2100) Ra-Shalom, and (ii) $ for (138852) 2000 WN10. The analysis of Ra-Shalom also reveals a precession of the spin axis with a precession constant $ $. This is the first such detection from Earth-bound photometric data. For the other two asteroids, we improved the accuracy of the previously reported YORP detection: (i) $ for (1862) Apollo, and (ii) $ for (161989) Cacus. With this value, Apollo has the most precisely determined YORP effect so far. Despite the recent report of a detected YORP effect for (85989) 1999 JD6, we show that the model without YORP cannot be rejected statistically. Therefore, the detection of the YORP effect for this asteroid requires future observations. In several of our targets the currently available observations do not provide enough constraints on the shape model (even at large scales) to compute the theoretical YORP effect with sufficient precision. Nevertheless, the interpretation of the detected signal as the YORP effect is fairly plausible. The spin-axis precession constant of Ra-Shalom determined from observations matches the theoretically expected value. The total number of asteroids with a YORP detection has increased to 12. In all cases, the rotation frequency increases in time. The analysis of a rich photometric data set of irregularly shaped asteroids may require inclusion of spin-axis precession in future studies.

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Section: (85989) 1999 Jd6contrasting

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Section: (85989) 1999 Jd6mentioning

confidence: 99%

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Secular change in the spin states of asteroids due to radiation and gravitation torques

Ďurech,

Vokrouhlický,

Pravec

et al. 2024

A&A

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“…Muinonen et al (2022) provided error models for four classes of lightcurves and used linear or linear-exponential phase functions for phase angles below 50°. Tian et al (2022) measured the YORP effect of (1685) Toro and (85989) 1999 JD6 by inverting their lightcurves, providing new detections of this effect and insights into the evolution of small asteroids.…”

Section: Introductionmentioning

confidence: 99%

Accelerating Asteroidal Period and Pole Inversion from Multiple Lightcurves Using Parallel Differential Evolution and Cellinoid Shape Model

Zhang,

Guo,

et al. 2024

Res. Astron. Astrophys.

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Determining asteroid properties provides valuable physical insights but inverting them from photometric lightcurves remains computationally intensive. This paper presents a new approach that combines a simplified Cellinoid shape model with the Parallel Differential Evolution (PDE) algorithm to accelerate inversion. The PDE algorithm is more efficient than the Differential Evolution (DE) algorithm, achieving an extraordinary speedup of 37.983 with 64 workers on multicore CPUs. The PDE algorithm accurately derives period and pole values from simulated data. The analysis of real asteroid lightcurves validates the method's reliability: in comparison with results published elsewhere, the PDE algorithm accurately recovers the rotational periods and, given adequate viewing geometries, closely matches the pole orientations. The PDE approach converges to solutions within 20,000 iterations and under one hour, demonstrating its potential for large-scale data analysis. This work provides a promising new tool for unveiling asteroid physical properties by overcoming key computational bottlenecks.

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A semi-analytical thermal model for craters with application to the crater-induced YORP effect

Zhou,

Michel

2024

A&A

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The YORP effect is the thermal torque generated by radiation from the surface of an asteroid. The effect is sensitive to surface topology, including small-scale roughness, boulders, and craters. The aim of this paper is to develop a computationally efficient semi-analytical model for the crater-induced YORP (CYORP) effect that can be used to investigate the functional dependence of this effect. This study linearizes the thermal radiation term as a function of the temperature in the boundary condition of the heat conductivity, and obtains the temperature field in a crater over a rotational period in the form of a Fourier series, accounting for the effects of self-sheltering, self-radiation, and self-scattering. By comparison with a numerical model, we find that this semi-analytical model for the CYORP effect works well for $K>0.1 W/m/K$. This semi-analytical model is computationally three-orders-of-magnitude more efficient than the numerical approach. We obtain the temperature field of a crater, accounting for the thermal inertia, crater shape, and crater location. We then find that the CYORP effect is negligible when the depth-to-diameter ratio is smaller than 0.05. In this case, it is reasonable to assume a convex shape for YORP calculations. Varying the thermal conductivity yields a consistent value of approximately 0.01 for the spin component of the CYORP coefficient, while the obliquity component is inversely related to thermal inertia, declining from 0.004 in basalt to 0.001 in metal. The CYORP spin component peaks at an obliquity of $0^ or $180^ while the obliquity component peaks at an obliquity of around $45^ or $135^ For a z-axis symmetric shape, the CYORP spin component vanishes, while the obliquity component persists. Our model confirms that the total YORP torque is damped by a few tens of percent by uniformly distributed small-scale surface roughness. Furthermore, for the first time, we calculate the change in the YORP torque at each impact on the surface of an asteroid explicitly and compute the resulting stochastic spin evolution more precisely. This study shows that the CYORP effect due to small-scale surface roughness and impact craters is significant during the history of asteroids. The semi-analytical method that we developed, which benefits from fast computation, offers new perspectives for future investigations of the YORP modeling of real asteroids and for the complete rotational and orbital evolution of asteroids accounting for collisions. Future research employing our CYORP model may explore the implications of space-varying roughness distribution, roughness in binary systems, and the development of a comprehensive rotational evolution model for asteroid groups.

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Shape Model and Rotation Acceleration of (1685) Toro and (85989) 1999 JD6 from Optical Observations

Cited by 4 publications

References 50 publications

Secular change in the spin states of asteroids due to radiation and gravitation torques

Secular change in the spin states of asteroids due to radiation and gravitation torques

Accelerating Asteroidal Period and Pole Inversion from Multiple Lightcurves Using Parallel Differential Evolution and Cellinoid Shape Model

A semi-analytical thermal model for craters with application to the crater-induced YORP effect

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