Distribution of spin axes and senses of rotation for 20 large asteroids

Magnusson, P.

doi:10.1016/0019-1035(86)90072-2

Cited by 89 publications

(43 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Only eight objects (2,Pallas,7 Iris,8 Flora,16 Psyche,22 Kalliope,28 Bellona,433 Eros,and 704 Interamnia) are found in the range 80 • < ε < 100 • . This conforms the remark made by Michalowski (1993) and also agrees with Magnusson (1986Magnusson ( , 1990 who analyzes the spin vectors of 20 to 30 asteroids respectively. When quoting the apparent lack of poles with axes close to the ecliptic, this last author attributed this deficiency to an observational selection effect: an asteroid with a pole at a low ecliptic latitude is naturally less suitable to present a significant amplitude of the lightcurve variation.…”

Section: Results and Statisticssupporting

confidence: 92%

“…Thanks to our relatively large sample of 100 asteroids, we were able to analyze the asteroid data and to derive some statistical properties of the rotational characteristics. Concerning the distribution of obliquities, main features are revealed, which agree with previous authors (Drummond et al (1988(Drummond et al ( , 1991; Magnusson (1986Magnusson ( , 1990; Michalowski (1993); Pravec et al (2002)). However, the results in these studies are affected, because they aproximated the orbital plane by the ecliptic for the calculation of the obliquity, while we used the true orbital plane that enabled us to calculate the more accurate value of the obliquity.…”

Section: Resultssupporting

confidence: 91%

“…Drummond et al (1988Drummond et al ( , 1991 confirmed the bimodality of the observed pole distribution using results for 26 asteroids. If they used the same explanation as Magnusson (1986Magnusson ( , 1990 for this distribution, they did not exclude the possibility that the bimodality may be real and may reflect a primordial distribution of spin rates. Another confirmation of the non-uniform distribution of spin axes comes from Pravec et al (2002), who use a larger sample of asteroid-pole estimates than the authors above.…”

Section: Results and Statisticsmentioning

confidence: 99%

See 2 more Smart Citations

Obliquity, precession rate, and nutation coefficients for a set of 100 asteroids

Lhotka¹,

Souchay²,

Shahsavari³

2013

A&A

View full text Add to dashboard Cite

Context. Thanks to various space missions and the progress of ground-based observational techniques, the knowledge of asteroids has considerably increased in the recent years. Aims. Due to this increasing database that accompanies this evolution, we compute for a set of 100 asteroids their rotational parameters: the moments of inertia along the principal axes of the object, the obliquity of the axis of rotation with respect to the orbital plane, the precession rates, and the nutation coefficients. Methods. We select 100 asteroids for which the parameters for the study are well-known from observations or space missions. For each asteroid, we determine the moments of inertia, assuming an ellipsoidal shape. We calculate their obliquity from their orbit (instead of the ecliptic) and the orientation of the spin-pole. Finally, we calculate the precession rates and the largest nutation components. The number of asteroids concerned leads to some statistical studies of the output. Results. We provide a table of rotational parameters for our set of asteroids. The table includes the obliquity, their axes ratio, their dynamical ellipticity H d , and the scaling factor K. We compute the precession rateψ and the leading nutation coefficients Δψ and Δε. We observe similar characteristics, as observed by previous authors that is, a significantly larger number of asteroids rotates in the prograde mode (≈60%) than in the retrograde one with a bimodal distribution. In particular, there is a deficiency of objects with a polar axis close to the orbit. The precession rates have a mean absolute value of 18 /y, and the leading nutation coefficients have an average absolute amplitude of 5.7 for Δψ and 5.2 for Δε. At last, we identify and characterize some cases with large precession rates, as seen in 25143 Itokawa, with has a precession rate of about −475 /y.

show abstract

Section: Results and Statisticssupporting

confidence: 92%

Section: Resultssupporting

confidence: 91%

Section: Results and Statisticsmentioning

confidence: 99%

See 1 more Smart Citation

Obliquity, precession rate, and nutation coefficients for a set of 100 asteroids

Lhotka¹,

Souchay²,

Shahsavari³

2013

A&A

View full text Add to dashboard Cite

show abstract

“…A more recent analysis by the same authors (priv. communication) resulted in a rotation model with slightly different values: λ ecl = 327.3 • , β ecl = +34.7 • , P sid = 7.6273922 h. Both solutions were derived using the epoch and amplitude methods described by Magnusson (1986). These methods are reliable for irregularly shaped bodies and for sufficient lightcurve data covering various aspect angles.…”

Section: Possible Shape and Spin-vector Solutionsmentioning

confidence: 99%

Thermo-physical properties of 162173 (1999 JU3), a potential flyby and rendezvous target for interplanetary missions

Müller

Ďurech

Hasegawa

et al. 2010

A&A

View full text Add to dashboard Cite

Context. Near-Earth asteroid 162173 (1999 JU3) is a potential flyby and rendezvous target for interplanetary missions because of its easy-to-reach orbit. The physical and thermal properties of the asteroid are relevant for establishing the scientific mission goals and also important in the context of near-Earth object studies in general. Aims. Our goal was to derive key physical parameters such as shape, spin-vector, size, geometric albedo, and surface properties of 162173 (1999 JU3). Methods. With three sets of published thermal observations (ground-based N-band, Akari IRC, Spitzer IRS), we applied a thermophysical model to derive the radiometric properties of the asteroid. The calculations were performed for the full range of possible shape and spin-vector solutions derived from the available sample of visual lightcurve observations. Results. The near-Earth asteroid 162173 (1999 JU3) has an effective diameter of 0.87 ± 0.03 km and a geometric albedo of 0.070 ± 0.006. The χ 2 -test reveals a strong preference for a retrograde sense of rotation with a spin-axis orientation of λ ecl = 73 • , β ecl = −62 • and P sid = 7.63 ± 0.01 h. The most likely thermal inertia ranges between 200 and 600 J m −2 s −0.5 K −1 , about a factor of 2 lower than the value for 25143 Itokawa. This indicates that the surface lies somewhere between a thick-dust regolith and a rock/boulder/cm-sized, gravel-dominated surface like that of 25143 Itokawa. Our analysis represents the first time that shape and spin-vector information has been derived from a combined data set of visual lightcurves (reflected light) and mid-infrared photometry and spectroscopy (thermal emission).

show abstract

“…Poles and shapes for these asteroids have been determined using the Epoch/Amplitude method (see Taylor 1979;Magnusson 1986 andMagnusson et al 1989). Lightcurve data reported in the literature together with lightcurves obtained here for these asteroids have been used in the analysis.…”

Section: Poles and Shapesmentioning

confidence: 99%