Collisional Spin Up of Nonspherical Asteroids

Yanagisawa, Masahisa

doi:10.1006/icar.2002.6928

Cited by 7 publications

(7 citation statements)

References 12 publications

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“…Furthermore, the lunar Leonids allowed us to determine the luminous efficiency of such collision processes (Bellot Rubio, Ortiz, & Sada 2000a), and it became clear that optical flashes can be detected on a regular basis. Yanagisawa & Kisaichi (2002) have also reported impact flash observations during the 1999 Leonids, which were obtained while the meteoroid flux levels were presumably much lower than in the case of the observations reported in Dunham et al (2000) and Ortiz et al (2000). Yanagisawa & Kisaichi also reported that their impact flashes had protracted afterglows, in clear contrast to the storm observations.…”

Section: Introductionmentioning

confidence: 79%

“…Concerning the issue of the long duration of the brightest impact flash, it is yet unclear what the physical process acting to produce such a kind of afterglow might be. Yanagisawa & Kisaichi (2002) proposed that the thermal emission No. 1, 2002 from $100 lm droplets from the lunar soil vaporized and recondensed in flight may be responsible for the protracted afterglows they recorded.…”

Section: Discussionmentioning

confidence: 99%

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Observation and Interpretation of Leonid Impact Flashes on the Moon in 2001

Ortiz¹,

Quesada²,

Aceituno³

et al. 2002

ApJ

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We present observations of lunar Leonid impact flashes recorded in 2001 November from Spain. Four impact flashes were detected on November 18. Another flash was also recorded on the same night, which appears to be impact related, and two more on that night are possibly, but not unambiguously, of impact nature. On November 19 another flash was detected, which very likely resulted from an impact. The brightest impact flash reached a peak brightness of 5:2 AE 0:3 mag in V; it had a very dim precursor just 0.02 s prior to peak brightness and had a very long lasting afterglow that remained visible for more than 600 ms with oscillations in brightness; this unique and unexpected behavior challenges current models of impact flashes. The other flashes did not show such a behavior and remained visible for a few tens of milliseconds. Adopting the luminous efficiency derived for the 1999 lunar Leonids (2 Â 10 À3 ), our observations can be used to estimate meteoroid fluxes. The observations are compatible with a flux of 0.1 meteoroids of mass larger than 2 Â 10 À8 kg km À2 hr À1 on November 18 at 18:15 UT, provided that a mass index of 1.69 is used. Both the flux and the mass index agree with meteor observations carried out in 2001 from several locations on Earth.

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Section: Introductionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Observation and Interpretation of Leonid Impact Flashes on the Moon in 2001

Ortiz¹,

Quesada²,

Aceituno³

et al. 2002

ApJ

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“…In general, small impactors produce craters on the target's surface, and deliver certain amounts of linear and angular momentum. Several studies have been devoted to the analysis of the evolution of asteroid spin rates and re‐orientations of spin directions due to non‐destructive collisions with other objects, both on the basis of theoretical analysis and by means of laboratory experiments (Dobrovolskis & Burns 1984; Fujiwara 1987; Harris 1979, 1990; Yanagisawa, Hasegawa & Shirogane 1996; Yanagisawa & Hasegawa 2000; Yanagisawa 2002). On the other hand, very little has been done so far in order to investigate the consequences of linear momentum transfer to the orbit of the target, since this has been generally assumed to be a very minor effect.…”

Section: Introductionmentioning

confidence: 99%

The random walk of Main Belt asteroids: orbital mobility by non-destructive collisions

Dell’Oro

Cellino

2007

Monthly Notices of the Royal Astronomical Society

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Non‐destructive collisions among Main Belt asteroids have effects on their orbits due to the transmission of linear momentum. The efficiency of this mechanism depends on several parameters which are currently poorly known. The most critical aspects are (i) the inventory and size distribution of small Main Belt asteroids, with sizes well below a few kilometres; (ii) the energy threshold for collisional fragmentation and fragment dispersion and (iii) the efficiency of linear momentum transfer. In spite of these difficulties, a general statistical model of the dynamical effects of non‐destructive collisions can be developed, and is presented here. Based on this model, the consequences of different assumptions concerning the asteroid size distribution and collision physics are computed and discussed. Quantitative evaluations of the collisionally induced orbital mobility in different possible scenarios are presented.

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“…For basaltic targets they give η0 = 1.52 and ζ0 = 0.409. For sand target which could be similar to a regolith-covered asteroid, Yanagisawa (2002) gives ζ0 = 0.687. He did not obtain the η0 value and therefore he uses η0 = 0 (η = 1) for an asteroid large enough to 3 The efficiency can be larger than one because backfire ejecta carries away some momentum in the direction opposite to the projectile course.…”

Section: Angular Momentum Transfer Efficiencymentioning

confidence: 99%

“…There is also a relation between the efficiencies and the shape of the target body as described in Yanagisawa (2002). It is sufficient to consider the equations given above since the impact angle σ is different for a sphere and an ellipsoid for the same impact velocity and therefore we get different values of η and ζ for different target shapes.…”

Section: Angular Momentum Transfer Efficiencymentioning

confidence: 99%

Asteroid rotation excitation by subcatastrophic impacts

Henych¹,

Pravec²

2013

Monthly Notices of the Royal Astronomical Society

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Photometric observations of asteroids show that some of them are in non-principal axis rotation state (free precession), called tumbling. Collisions between asteroids have been proposed as a possible asteroid rotation excitation mechanism. We simulated subcatastrophic collisions between asteroids of various physical and material parameters to find out whether they could be responsible for the excited rotation. For every simulated target body after the collision, we computed its rotational lightcurve and we found that tumbling was photometrically detectable for the rotational axis misalignment angle β greater than about 15 • . We found that subcatastrophic collisions are a plausible cause of non-principal axis rotation for small slowly rotating asteroids. The determining parameter is the ratio of the projectile orbital angular momentum to the target rotational angular momentum and we derived an approximate relation between this ratio and the angle β. We also compared the limiting energy for the onset of tumbling with the shattering energy. Slowly rotating asteroids of diameter 100 m and larger can be rotationally excited by collisions with energies below the shattering limit.

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Collisional Spin Up of Nonspherical Asteroids

Cited by 7 publications

References 12 publications

Observation and Interpretation of Leonid Impact Flashes on the Moon in 2001

Observation and Interpretation of Leonid Impact Flashes on the Moon in 2001

The random walk of Main Belt asteroids: orbital mobility by non-destructive collisions

Asteroid rotation excitation by subcatastrophic impacts

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