Spectral type and geometric albedo of (98943) 2001 CC21, the <i>Hayabusa2#</i> mission target

Geem, Jooyeon; Ishiguro, Masateru; Granvik, Mikael; Naito, H.; Akitaya, Hiroshi; Sekiguchi, T.; Hasegawa, Susumu; Kuroda, D.; Oono, Tatsuharu; Bach, Yoonsoo P.; Jin, Sunho; Imazawa, Ryo; Kawabata, Koji S.; Takagi, Seiko; Yoshikawa, Makoto; Djupvik, A. A.; Gadeberg, Julie Thiim; Pursimo, T.; Pedros, Oliver Durfeldt; Thomsen, Jeppe Sinkbaek; Gray, Zuri

doi:10.1093/mnrasl/slad073

Cited by 4 publications

(1 citation statement)

References 32 publications

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“…5 km) , b/a ( 0 < b/a ≤ 1 ) , and PA ( 0 ≤ PA < π ) . For the mean radius, √ (ab) , we adopt a normal prior distribution, anchored to the recent estimates from optical polarimetry and near-infrared spectroscopy observations by Geem et al ( 2023 ) . We assume √ (ab) = 0 .…”

Section: Mcmc Fitmentioning

confidence: 99%

Diffraction modelling of a 2023 March 5 stellar occultation by subkilometer-sized asteroid (98943) 2001 CC21

Arimatsu,

Yoshida,

Hayamizu

et al. 2024

Publications of the Astronomical Society of Japan

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We present an analysis of a stellar occultation event caused by a near-Earth asteroid (98943) 2001 CC21, an upcoming flyby target in the Hayabusa2 extended mission, on 2023 March 5. To determine the asteroid’s shape from diffraction-affected light curves accurately, we developed a novel data-reduction technique named the Diffracted Occultation’s United Simulator for Highly Informative Transient Explorations (DOUSHITE). Using DOUSHITE-generated synthetic models, we derived constraints on (98943) 2001 CC21’s shadow shape from the single-chord occultation data. Our results suggest a significant elongation of the shadow with an axis ratio of $b/a = 0.37\pm 0.09$. This shape could be crucial for planning Hayabusa2’s high-speed flyby to optimise the limited imaging opportunities.

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Section: Mcmc Fitmentioning

confidence: 99%

Diffraction modelling of a 2023 March 5 stellar occultation by subkilometer-sized asteroid (98943) 2001 CC21

Arimatsu,

Yoshida,

Hayamizu

et al. 2024

Publications of the Astronomical Society of Japan

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Quantitative grain size estimation on airless bodies from the negative polarization branch

Bach,

Ishiguro,

Takahashi

et al. 2024

A&A

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This work explores characteristics of the negative polarization branch (NPB), which occurs in scattered light from rough surfaces, with particular focus on the effects of fine particles. Factors such as albedo, compression, roughness, and the refractive index are considered to determine their influence on the NPB. This study compiles experimental data and lunar observations to derive insights from a wide array of literature. Employing our proposed methodology, we estimate the representative grain sizes on the lunar surface to be $D with $D consistent with observed grain size frequency distributions in laboratory settings for lunar fines. Considering Mars, we propose that the finest particles are likely lacking ($D which matches previous estimations. This study highlights the potential of multiwavelength, particularly near-infrared, polarimetry for precisely gauging small particles on airless celestial bodies. The conclusions provided here extend to cross-validation with grain sizes derived from thermal modeling, asteroid taxonomic classification, and regolith evolution studies.

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Study of hydrated asteroids via their polarimetric properties at low phase angles

Geem,

Ishiguro,

Naito

et al. 2024

A&A

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Ch-type asteroids are distinctive among other dark asteroids in that they exhibit deep negative polarization branches (NPBs). Nevertheless, the physical and compositional properties that cause their polarimetric distinctiveness are less investigated. We aim to investigate the polarimetric uniqueness of Ch-type asteroids by making databases of various observational quantities (i.e., spectroscopic and photometric properties as well as polarimetric ones) of dark asteroids. We conducted an intensive polarimetric survey of 52 dark asteroids (including 31 Ch-type asteroids) in the $R_ C $ band to increase the size of polarimetric samples. The observed data were compiled with previous polarimetric, spectroscopic, and photometric archival data to find their correlations. We find remarkable correlations between these observed quantities, particularly the depth of NPBs and their spectroscopic features associated with the hydrated minerals. The amplitude of the opposition effect in photometric properties also shows correlations with polarimetric and spectral properties. However, these observed quantities do not show noticeable correlations with the geometric albedo, thermal inertia, and diameter of asteroids. Based on the observational evidence, we arrive at our conclusion that the submicrometer-sized structures (fibrous or flaky puff pastry-like structures in phyllosilicates) in the regolith particles could contribute to the distinctive NPBs of hydrated asteroids.

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Spectral type and geometric albedo of (98943) 2001 CC21, the Hayabusa2# mission target

Cited by 4 publications

References 32 publications

Diffraction modelling of a 2023 March 5 stellar occultation by subkilometer-sized asteroid (98943) 2001 CC21

Diffraction modelling of a 2023 March 5 stellar occultation by subkilometer-sized asteroid (98943) 2001 CC21

Quantitative grain size estimation on airless bodies from the negative polarization branch

Study of hydrated asteroids via their polarimetric properties at low phase angles

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