Radar and Optical Observations of Asteroid 1998 KY26

Ostro, S. J.; Pravec, Petr; Benner, L. A. M.; Hudson, R. S.; Šarounová, L.; Hicks, Michael; Rabinowitz, D.; Scotti, J. V.; Tholen, David J.; Wolf, M.; Jurgens, R. F.; Michael, Thomas; Giorgini, Jon D.; Chodas, P. W.; Yeomans, Donald K.; Rose, Randall L.; Frye, R.C.; Rosema, K. D.; Winkler, R.; Slade, M. A.

doi:10.1126/science.285.5427.557

Cited by 67 publications

(44 citation statements)

References 22 publications

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“…This small, spheroidal, diameter D % 30 m object has an Earth-crossing orbit (semimajor axis a ¼ 1:23 AU, eccentricity e ¼ 0:20, and inclination i ¼ 1:5 ). Radar observations in 1998 revealed its precise surface shape, a composition analogous to carbonaceous chondritic meteorites, and very fast rotation, with the period only 10.7 minutes, suggesting a monolithic interior (Ostro et al 1999). In addition, it was inferred that 1998 KY 26 has visual albedo 0:2 AE 0:15 and %2.8 g cm À3 density.…”

Section: Application To Asteroid 1998 Ky 26mentioning

confidence: 99%

“…This can explain the present fast rotation rate of 1998 KY 26 (! % 9:8 ; 10 À3 s À1 ; Ostro et al 1999). With d!/dt $ 1Y 4 ð Þ; 10 À7 s À1 yr À1 (Fig.…”

Section: Application To Asteroid 1998 Ky 26mentioning

confidence: 99%

“…We used the shape model of 1998 KY 26 currently available on the Planetary Data System ( PDS) node (Ostro et al 1999). This shape model consists of 2048 vertices that define 4092 flatsurface triangles.…”

Section: Application To Asteroid 1998 Ky 26mentioning

confidence: 99%

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Analytic Theory of the YORP Effect for Near-Spherical Objects

Nesvorný¹,

Vokrouhlický²

2007

Astron J

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The YORP effect is produced when the surface of a small object in interplanetary space is heated by sunlight and reradiates the absorbed energy in thermal wavelengths. The absorbed, reflected, and emitted photons produce tiny torques on the small body that can change its spin rate and obliquity over planetary timescales. Previous theories of the YORP effect relied on numerical or seminumerical evaluation of the radiation torques. Here we develop an alternative approach and calculate the YORP torques analytically. Our theory is limited to near-spherical objects. While unsuitable for a precise determination of torques on elongated and /or highly irregular objects, the analytic theory helps to explain several general properties of the YORP torques that were identified in previous numerical works. For example, we demonstrate that the component of the YORP torque that affects the spin rate,¯s, can vanish for obliquity values % 55 (and % 125 ). As discussed by Vokrouhlický and coworkers, this property of¯s is important for establishing the so-called Slivan states, which arise as evolutionary end states of spin vectors of small solar system bodies such as asteroids. We show that¯s (averaged over spin and orbit periods) is a second-order quantity in the small parameter that describes the deviation of the shape from an ideal sphere. We calculate¯s explicitly as polynomials of cos . These expressions show that the YORP torque arises from coupled deformations of the body's shape in topographic longitude and latitude. Moreover, by introducing a small phase lag to mimic the delay between the absorption and reemission of photons we demonstrate that¯s is insensitive to the exact value of the surface thermal conductivity. These and other analytic results described here provide a baseline for understanding the YORP effect on bodies with more complicated surface shapes and properties other than the ones considered here. We discuss applications of the analytic theory on near-spherical asteroids like 1998 KY 26 and on more elongated and/or irregular objects like (1862) Apollo and (25143) Itokawa.

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Section: Application To Asteroid 1998 Ky 26mentioning

confidence: 99%

“…This can explain the present fast rotation rate of 1998 KY 26 (! % 9:8 ; 10 À3 s À1 ; Ostro et al 1999). With d!/dt $ 1Y 4 ð Þ; 10 À7 s À1 yr À1 (Fig.…”

Section: Application To Asteroid 1998 Ky 26mentioning

confidence: 99%

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Analytic Theory of the YORP Effect for Near-Spherical Objects

Nesvorný¹,

Vokrouhlický²

2007

Astron J

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“…The first asteroids with rotation periods shorter than 2.2 h were 1995 HM (P = 97 min, Steel et al 1997) and1998 KY 26 (P = 10.7 min, Ostro et al 1999). With a discovery of three new A&A 509, A94 (2010) such objects (1999TY 2 , 1999 and 1998 WB 2 , Pravec et al 2000) it became clear that there exists a population of very small (H > 21.5 mag), fast rotating asteroids.…”

Section: Introductionmentioning

confidence: 99%

“…With a discovery of three new A&A 509, A94 (2010) such objects (1999TY 2 , 1999 and 1998 WB 2 , Pravec et al 2000) it became clear that there exists a population of very small (H > 21.5 mag), fast rotating asteroids.…”

Section: Introductionmentioning

confidence: 99%

Photometric survey of the very small near-Earth asteroids with the SALT telescope

Kwiatkowski¹,

Buckley

O’Donoghue

et al. 2010

A&A

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Aims. We report first results from our extensive survey of the very small (H > 21.5 mag) near-Earth asteroids. Our aim was to obtain photometric lightcurves for these faint, fast moving objects and to measure their rotation periods and amplitudes of light variations. These parameters can be used to make statistical analysis of the still little known population of the smallest asteroids, test present theories of the YORP effect as well as to study their spin limits, which are connected with their internal structure. Methods. Due to the faintness of the targets and the expected short periods of rotation, observations were performed with the large, 10-m SALT telescope in SAAO (South Africa). For most asteroids, V filter images with exposure times of 5-60 s were obtained with the instrument's SALTICAM's CCD camera. Even though the non-sidereal tracking was not available, the SALTICAM's relatively large field-of-view of 8 × 8 helped to perform the relative photometry of the fast-moving targets. Results. The presented asteroids have synodic periods ranging from 77 s to 44 min, effective diameters from 21 to 94 m, and significantly elongated shapes.

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