THE YARKOVSKY AND YORP EFFECTS: Implications for Asteroid Dynamics

Bottke, W. F.; Vokrouhlický, David; Rubincam, David Parry; Nesvorný, David

doi:10.1146/annurev.earth.34.031405.125154

Cited by 683 publications

(640 citation statements)

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“…1950 DA might have had large boulders present on its surface in the past, but these would have been progressively lost in order of size as it was spun-up by the YORP effect (i.e. spin state changes caused by the anisotropic reflection and thermal re-emission of sunlight from an irregular shaped asteroid 10 ).…”

mentioning

confidence: 99%

Cohesive forces prevent the rotational breakup of rubble-pile asteroid (29075) 1950 DA

Rozitis

MacLennan

Emery

2014

Nature

180

137

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Space missions 1 and ground-based observations 2 have shown that some asteroids are loose collections of rubble rather than solid bodies. The physical behavior of such 'rubble pile' asteroids has been traditionally described using only gravitational and frictional forces within a granular material 3 . Cohesive forces in the form of small van der Waals forces between constituent grains have been recently predicted to be important for small rubble piles (10-kilometer-sized or smaller), and can potentially explain fast rotation rates in the small asteroid population 4-6 . Hitherto, the strongest evidence came from an analysis of the rotational breakup of main belt comet P/2013 R3 (ref. 7), although that was indirect and poorly constrained by present observations. Here we report that the kilometer-sized asteroid (29075) 1950 DA 8 is a rubble pile that is rotating faster than that allowed by gravity and friction. We find that cohesive forces are required to prevent surface mass shedding and structural failure, and that the strength of the forces are comparable to, though somewhat less than, that of lunar regolith.It is possible to infer the existence of cohesive forces within an asteroid by determining if it is a rubble pile with insufficient self-gravity to prevent rotational breakup by centrifugal forces. One of the largest known candidates is near-Earth asteroid 1950 DA (mean diameter of 1.3 km; ref.8), as it has a rotation period of 2.1216 hr that is just beyond the critical spin limit of ~2.2 hr estimated for a cohesionless asteroid 9 . A rubble pile structure and the degree of self-gravity can be determined by a bulk density measurement, which can be acquired through model-tomeasurement comparisons of Yarkovsky orbital drift 10 . This drift arises on a rotating asteroid with non-zero thermal inertia, and is caused by the delayed thermal emission of absorbed sunlight, which applies a small propulsion force to the asteroid's afternoon side. Thermalinfrared observations can constrain the thermal inertia value 11 , and precise astrometric position measurements conducted over several years can constrain the degree of Yarkovsky orbital drift 2 . Recently, the orbital semimajor axis of 1950 DA has been observed to be decreasing at a rate of 44.1 ± 8.5 m yr -1 because of the Yarkovsky effect 12 , which indicates that the asteroid's sense of rotation must be retrograde. Using the Advanced Thermophysical Model 13,14 , in combination with the retrograde radar shape model 8 , archival WISE thermal-infrared data 15 (Extended Data Table 1, and Extended Data Figs 1 and 2), and orbital state 12 , we determine the thermal inertia and bulk density of 1950 DA (Methods). The thermal inertia value is found to be remarkably low at 24 +20 / -14 J m -2 K -1 s -1/2 , which gives a corresponding bulk density of 1.7 ± 0.7 g cm -3 ( Fig. 1 and Extended Data Fig. 3). This bulk density is much lower than the minimum value of 3.5 g cm -3 required to prevent loss of surface material by centrifugal forces (Fig. 2).Spectral observations of 1950...

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mentioning

confidence: 99%

Cohesive forces prevent the rotational breakup of rubble-pile asteroid (29075) 1950 DA

Rozitis

MacLennan

Emery

2014

Nature

180

137

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“…We note that population of asteroids with size ≤30 km was found to be strongly affected by the Yarkovsky-O'KeefeRadzievsky-Paddack (YORP) effect (e.g., Bottke et al 2006;Vokrouhlický et al 2015). In particular, YORP is able to accelerate rotation rate of asteroids and make part of the population rotate very fast (e.g., Pravec et al 2008).…”

Section: Discussionmentioning

confidence: 92%

“…12. As to the last term, we note that sub-kilometer size observed Datura members may haveȧ prop 5 × 10 −4 au Myr −1 (e.g., Bottke et al 2006;Vokrouhlický et al 2015) or smaller, which implies the third term in Eq. (1) may be approximately 0.7 • , about an order of magnitude smaller than the second term, but already larger than the first term.…”

Section: Datura Membership Updatementioning

confidence: 94%

“…In the case of smaller objects, we must account for both negative and positive drift-rates in some maximum limits (da/dt) max . This value is 2 × 10 −4 au Myr −1 for a kilometer-size asteroid in the Datura heliocentric distance (e.g., Bottke et al 2006). For objects of a different sizes D, we use the standard scaling (da/dt) max ∝ 1/D.…”

Section: Past Convergence Of Datura Membersmentioning

confidence: 95%

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The young Datura asteroid family

Vokrouhlický

Pravec

Ďurech

et al. 2017

A&A

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Context. Asteroid families are the outcomes of disruption or cratering events on a size and energy scales that are not reproducible in laboratory experiments. Overall structure, as well as properties of individual members, in the old families could have been changed since their formation. Therefore young families preserve best the characteristics of the initial event. Aims. We study the most suitable known asteroid family with an age of less than 1 Myr, the Datura family. We aim (i) to obtain information about rotation state and shape of the largest members in the family; and (ii) to constrain its debiased population down to couple of hundreds of meters in size. Methods. We have analyzed the up-to-date catalog of orbital elements of main belt asteroids. We evaluated the detection efficiency of Catalina Sky Survey (CSS) in regard to detections of members in the Datura family, and we have used our photometric observations and lightcurve inversion methods to determine the rotation states and shapes of the largest members of the family. Results. We determined rotation periods of the seven largest members of the Datura family, and we also derived accurate mean absolute magnitudes for six of them. Except for the largest fragment (1270) Datura, the asteroids tend to have long rotation periods and large amplitude of the lightcurve, witnessing an elongated shape. For the four largest asteroids, our observations allow us to resolve rotation pole and a rough shape. All of them are prograde-rotating and have the latitude of the rotation pole >50 • . Our search in orbital catalogs resulted in the discovery of many small, sub-kilometer members of the Datura family. Using the CSS detection efficiency, we inverted this information into the debiased population of Datura family members. We show that the mass and angular momentum content in small fragments is negligible compared to the largest fragment (1270) Datura. These findings may help to constrain the formation mechanism of the family.

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“…The Classical Model for asteroids describes their evolution based on collisions and gravitational effects, but is unable to explain the origin of NEAs (Bottke, 2006). Non-gravitational forces, first discussed by Yarkovsky in the early 1900s, can help to reconcile this issue (Bottke, 2006).…”

Section: Reasons For Mass Lossmentioning

confidence: 99%

Rotational Properties of the Extraordinary Multi-tailed Asteroid P/2013 P5

Gustafsson¹

2015

OURJ

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Observations made with the Hubble Space Telescope in September 2013 revealed that the asteroid known as P/2013 P5 appeared to have six comet-like tails. Jewitt et al. (2013) concluded that this extraordinary structure and activity could not be explained by traditional near-surface ice sublimation or collision events ejecting particles from the asteroid's surface. Instead, the most likely explanation is that this unusual object has been spun-up by solar radiation forces to a critical limit which has resulted in the rotational disruption of the asteroid causing the unique six-tail structure. This interpretation predicts that the nucleus of this comet-like asteroid should be in rapid rotation. In November 2013, broadband photometry of P/2013 P5 was obtained with Lowell Observatory's 4.3-meter Discovery Channel Telescope using the Large Monolithic Imager to investigate the possibility of rapid rotation. While the variation in the rotational light curve from these data was too small to be justifiable, morphological changes in the nucleus-coma system were observed.

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THE YARKOVSKY AND YORP EFFECTS: Implications for Asteroid Dynamics

Cited by 683 publications

References 93 publications

Cohesive forces prevent the rotational breakup of rubble-pile asteroid (29075) 1950 DA

Cohesive forces prevent the rotational breakup of rubble-pile asteroid (29075) 1950 DA

The young Datura asteroid family

Rotational Properties of the Extraordinary Multi-tailed Asteroid P/2013 P5

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