YORP effect on real objects

Micheli, M.; Paolicchi, Paolo

doi:10.1051/0004-6361:20078918

Cited by 6 publications

(3 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…16a) has a much more complicated shape with zero YORP torque occurring at ~10° obliquity instead of near the usual critical angle. The smooth surface predictions match those produced by Vokrouhlický & Čapek (2002) and by Breiter, Bartczak & Czekaj (2010) using the same shape model, and the complicated shape of the obliquity dependence is consistent with objects having relatively weak YORP effects (Micheli & Paolicchi 2008). As demonstrated by the error bars in Fig.…”

Section: (1620) Geographos and (6489) Golevkasupporting

confidence: 72%

“…Each shape model consists of 1152 facets which represents a good compromise between shape accuracy and computation time required, and is also consistent with the number used in other works (e.g. Vokrouhlický & Čapek 2002;Micheli & Paolicchi 2008). Each artificial asteroid is scaled so that it has a volume equal to a 1 km diameter spherical asteroid, and each given a bulk density of 2500 kg m -3 .…”

Section: Gaussian-sphere Asteroidsmentioning

confidence: 94%

“…Rubincam 2000; Vokrouhlický & Čapek 2002; Micheli & Paolicchi 2008). As summarized by Micheli & Paolicchi (2008), Nesvorný & Vokrouhlický (2007) show analytically that it is caused by a complex coupling between insolation and longitudinal shape irregularities, and is also dependent on the spectrum of such irregularities.…”

Section: Parameter Sensitivitymentioning

confidence: 99%

See 2 more Smart Citations

The influence of rough surface thermal-infrared beaming on the Yarkovsky and YORP effects

Rozitis¹,

Green²

2012

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

It is now becoming widely accepted that photon recoil forces from the asymmetric reflection and thermal re-radiation of absorbed sunlight are, together with collisions and gravitational forces, primary mechanisms governing the dynamical and physical evolution of asteroids. The Yarkovsky effect causes orbital semimajor axis drift, and the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect causes changes in the rotation rate and pole orientation. We present an adaptation of the Advanced Thermophysical Model to simultaneously predict the Yarkovsky and YORP effects in the presence of thermal-infrared beaming caused by surface roughness, which has been neglected or dismissed in all previous models. Tests on Gaussian random sphere shaped asteroids, and on the real shapes of asteroids (1620) Geographos and (6489) Golevka, show that rough surface thermal-infrared beaming enhances the Yarkovsky orbital drift by typically tens of per cent but it can be as much as a factor of 2. The YORP rotational acceleration is on average dampened by up to a third typically but can be as much as one-half. We find that the Yarkovsky orbital drift is only sensitive to the average degree, and not to the spatial distribution, of roughness across an asteroid surface. However, the YORP rotational acceleration is sensitive to the surface roughness spatial distribution, and can add significant uncertainties to the predictions for asteroids with relatively weak YORP effects. To accurately predict either effect the degree and spatial distribution of roughness across an asteroid surface must be known.

show abstract

Section: (1620) Geographos and (6489) Golevkasupporting

confidence: 72%

Section: Gaussian-sphere Asteroidsmentioning

confidence: 94%

See 1 more Smart Citation

The influence of rough surface thermal-infrared beaming on the Yarkovsky and YORP effects

Rozitis¹,

Green²

2012

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

Extreme sensitivity of the YORP effect to small-scale topography

Statler

2009

Icarus

138

165

View full text Add to dashboard Cite

Radiation recoil (YORP) torques are shown to be extremely sensitive to small-scale surface topography, using numerical simulations. Starting from a set of "base objects" representative of the near-Earth object population, random realizations of three types of small-scale topography are added: Gaussian surface fluctuations, craters, and boulders. For each, the expected relative errors in the spin and obliquity components of the YORP torque caused by the observationally unresolved small-scale topography are computed. Gaussian power, at angular scales below an observational limit, produces expected errors of order 100% if observations constrain the surface to a spherical harmonic order l 10. For errors under 10%, the surface must be constrained to at least l = 20. A single crater with diameter roughly half the object's mean radius, placed at random locations, results in expected errors of several tens of percent. The errors scale with crater diameter D as D 2 for D > 0.3 and as D 3 for D < 0.3 mean radii. Objects that are identical except for the location of a single large crater can differ by factors of several in YORP torque, while being photometrically indistinguishable at the level of hundredths of a magnitude. Boulders placed randomly on identical base objects create torque errors roughly 3 times larger than do craters of the same diameter, with errors scaling as the square of the boulder diameter. A single boulder comparable to Yoshinodai on 25143 Itokawa, moved by as little as twice its own diameter, can alter the magnitude of the torque by factors of several, and change the sign of its spin component at all obliquities. Most of the total torque error produced by multiple unresolved craters is contributed by the handful of largest craters; but both large and small boulders contribute comparably to the total boulder-induced error. A YORP torque prediction derived from groundbased data can be expected to be in error by of order 100% due to unresolved topography. Small surface changes caused by slow spin-up or spin-down may have significant stochastic effects on the spin evolution of small bodies. For rotation periods between roughly 2 and 10 hours, these unpredictable changes may reverse the sign of the YORP torque. Objects in this spin regime may random-walk up and down in spin rate before the rubble-pile limit is exceeded and fissioning or loss of surface objects occurs. Similar behavior may be expected at rotation rates approaching the limiting values for tensile-strength dominated objects.

show abstract

Footprints of the YORP effect in asteroid families

Paolicchi

Knežević

2016

Icarus

View full text Add to dashboard Cite

The YORP effect affects not only the rotation rate, but also the spin orientation of asteroids. For this reason, due to Yarkovsky effect, it influences also the evolution of the semimajor axis with time. In asteroid dynamical families, the combined outcome can be a depletion of objects in the central part of the family, shown by the absolute magnitude vs. semimajor axis so-called V-plot. A reclassification of asteroid families, extended to a very large database of proper elements, has recently been performed by Milani et al. [2014] (Icarus, 239, 46-73). Only some of the related V-plots, used to estimate the age of several families, exhibit the depletion predicted above. In this paper we discuss the problem, introducing the concept of the YORP-eye and a general method of analysis. We show that the effect may sometimes be located in the low H tail, and thus difficult to detect. Moreover, it may be hindered by several anomalous physical properties of the family (asymmetry, cratering origin, multiple collisions history and so on). With a new method of analysis, we identify the footprints of the effect for most of the analysed families, obtaining also an independent estimate of the age of the family. In spite of the uncertainties, we obtain a very good agreement between these ages and those estimated on the basis of the slope of the V-plot: a result which supports both methods and the underlying physics

show abstract

YORP effect on real objects

Cited by 6 publications

References 15 publications

The influence of rough surface thermal-infrared beaming on the Yarkovsky and YORP effects

The influence of rough surface thermal-infrared beaming on the Yarkovsky and YORP effects

Extreme sensitivity of the YORP effect to small-scale topography

Footprints of the YORP effect in asteroid families

Contact Info

Product

Resources

About