Asteroid photometric and polarimetric phase curves: empirical interpretation

Kaasalainen, Sanna; Piironen, J.; Kaasalainen, M.; Harris, Alan W.; Muinonen, K.; Cellino, A.

doi:10.1016/s0019-1035(02)00020-9

Cited by 69 publications

(65 citation statements)

References 25 publications

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“…New observations were combined with the old data set and were analyzed using the lightcurve inversion method (Kaasalainen et al 2001(Kaasalainen et al , 2003b. The new physical model is very close to the previous one: λ = 48…”

Section: Modelmentioning

confidence: 96%

New photometric observations of asteroids (1862) Apollo and (25143) Itokawa – an analysis of YORP effect

Ďurech¹,

Vokrouhlický²,

Kaasalainen

et al. 2008

A&A

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Aims. Asteroid (1862) Apollo is one of two asteroids in which the YORP effect was detected. We carried out new photometric observations of Apollo in April 2007 to enlarge the time line and to derive a more precise shape and spin state model. We also observed another YORP-candidate, asteroid (25143) Itokawa, in December 2006 and January 2007 to obtain a longer time line. An estimation of the YORP strength on Itokawa based on its precise shape model from the Hayabusa mission predicted the deceleration to be already observable during the 2007 apparition. Methods. We used the lightcurve inversion method to model the shape and spin state of Apollo. For Itokawa, the shape and pole direction are known to a high degree of accuracy from the Hayabusa mission, so we used a modified version of lightcurve inversion with only two free parameters -the rotation period and its linear change in time.Results. The new model of Apollo confirms earlier results. The observed acceleration of Apollo's rotation rate is (5.5 ± 1.2) × 10 −8 rad d −2 , which is in agreement with the theoretically predicted value. For Itokawa, the theoretical YORP value is sensitive to the resolution of the shape model and lies in the range from −2 to −3 × 10 −7 rad d −2 . This is inconsistent with results of lightcurve inversion that place an upper limit to the change of Itokawa's rotation rate ∼1.5 × 10 −7 rad d −2 .

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Section: Modelmentioning

confidence: 96%

New photometric observations of asteroids (1862) Apollo and (25143) Itokawa – an analysis of YORP effect

Ďurech¹,

Vokrouhlický²,

Kaasalainen

et al. 2008

A&A

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“…4. The data were fitted with a linear-exponential function as described by Kaasalainen et al (2003). Similar curves were obtained by fitting the data with either a trigonometric fit (Lumme & Muinonen 1993) or parabolic fit.…”

Section: Polarimetrymentioning

confidence: 99%

Puzzling asteroid 21 Lutetia: our knowledge prior to the Rosetta fly-by

Belskaya

Fornasier

Krugly

et al. 2010

A&A

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Aims. A wide observational campaign was carried out in [2004][2005][2006][2007][2008][2009] that aimed to complete the ground-based investigation of Lutetia prior to the Rosetta fly-by in July 2010. Methods. We obtained BVRI photometric and V-band polarimetric measurements over a wide range of phase angles, and visible and infrared spectra in the 0.4-2.4 μm range. We analyze them with previously published data to retrieve information about Lutetia's surface properties.Results. Values of lightcurve amplitudes, absolute magnitude, opposition effect, phase coefficient, and BVRI colors of Lutetia surface seen at near pole-on aspect are determined. We define more precisely parameters of polarization phase curve and show their distinct deviation from any other moderate-albedo asteroid. An indication of possible variations in both polarization and spectral data across the asteroid surface are found. To explain features found by different techniques, we propose that (i) Lutetia has a non-convex shape, probably due to a large crater, and heterogeneous surface properties probably related to surface morphology; (ii) at least part of the surface is covered by a fine-grained regolith of particle size smaller than 20 μm; (iii) the closest meteorite analogues of Lutetia's surface composition are particular types of carbonaceous chondrites, or Lutetia has specific surface composition that is not representative among studied meteorites.

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“…Our new observations were combined with the older data of Wisniewski et al (1997) and Székely et al (2005), and analysed using the lightcurve inversion method of Kaasalainen and collaborators (e.g., Kaasalainen et al 2001Kaasalainen et al , 2003. This procedure provides a simultaneous solution of the fundamental rotation parameters, rotation period P, and pole position (λ, β), in addition to parameters describing the irregular shape of the asteroid.…”

Section: Spin State and Shape Of (1270) Daturamentioning

confidence: 99%

Datura family: the 2009 update

Vokrouhlický¹,

Ďurech²,

Michałowski

et al. 2009

A&A

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Context. Research of asteroid families has been recently refreshed by the discovery of very young ones. These families are of great interest because they represent the product of their parent body fragmentation before orbital and physical evolutionary processes can change them. A cluster of seven objects around the largest body (1270) Datura is of particular interest because it has enough known members and resides in the inner part of the main asteroid belt, facilitating observations. Aims. We carried out photometric observations of the two largest members of the Datura family -asteroids (1270) Datura and (90265) 2003 CL5 -with the goal of inferring their physical parameters. We also used numerous astrometric observations of Datura-family members in the past few years to revisit the age of this cluster. Methods. We performed numerous photometric observations of (1270) Datura over several oppositions. We then used the lightcurve inversion method to determine the spin state and shape of this asteroid. In the case of (90265) 2003 CL5, for which only limited lightcurve data have been acquired so far, we used Fourier analysis to determine the synodic rotation period during the 2008 apparition. We also used backward numerical integration of the improved orbits of Datura family members to reduce uncertainty in its age. Results. We determined the rotation state of (1270) Datura, the largest member of its own family. Its major properties are a short rotation period of ∼3.36 h and small obliquity, which, however, exhibits ∼±15 • excursions because of a forced Cassini state of the proper nodal frequency. Any possible initial non-principal rotation state has probably been damped and the asteroid rotates about the shortest axis of the inertia tensor. Its global shape, although convex in our representation, may reflect regions related to the excavation of the family members from the parent body surface. Interestingly, the second largest member of the Datura family -(90265) 2003 CL5 -appears to be very slow rotator with the rotation period ∼24 h. The large amplitude of its rotation curve suggests that its shape is extremely elongated, possibly bi-lobed. Improved orbits of the family members allow us to re-determine the possible age of this family. We find an age that is slightly older than previously reported. Using a conservative approach, we obtain an age in the 450 to 600 kyr range. With strengthened, but plausible, conditions, we find that the current data may support an age of 530±20 kyr. Further astrometric and photometric observations of the Datura cluster members are needed to determine its age more accurately.

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Asteroid photometric and polarimetric phase curves: empirical interpretation

Cited by 69 publications

References 25 publications

New photometric observations of asteroids (1862) Apollo and (25143) Itokawa – an analysis of YORP effect

New photometric observations of asteroids (1862) Apollo and (25143) Itokawa – an analysis of YORP effect

Puzzling asteroid 21 Lutetia: our knowledge prior to the Rosetta fly-by

Datura family: the 2009 update

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