Thermal Modeling of Comet-like Objects from AKARI Observation

Bach, Yoonsoo P.; Ishiguro, Masateru; Usui, Fumihiko

doi:10.3847/1538-3881/aa8dfe

Cited by 3 publications

(3 citation statements)

References 55 publications

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“…It is natural that 4015 Wilson-Harringtion, which is the near-Earth object, has a high surface temperature; thus, the thermal component fully occupies the wavelength coverage of the spectroscopy (λtrunc = 3.0 µm). We cannot retrieve any valid reflectance spectra from this object; instead, the spectral data of this object were utilized for studying the thermal properties of the asteroid (e.g., Bach, Ishiguro, & Usui 2017).…”

Section: Thermal Component Subtractionmentioning

confidence: 99%

AKARI/IRC near-infrared asteroid spectroscopic survey: AcuA-spec

Usui

Hasegawa

Ootsubo

et al. 2018

Publications of the Astronomical Society of Japan

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Knowledge of water in the solar system is important for understanding of a wide range of evolutionary processes and the thermal history of the solar system. To explore the existence of water in the solar system, it is indispensable to investigate hydrated minerals and/or water ice on asteroids. These water-related materials show absorption features in the 3-µm band (wavelengths from 2.7 to 3.1 µm). We conducted a spectroscopic survey of asteroids in the 3-µm band using the Infrared Camera (IRC) on board the Japanese infrared satellite AKARI. In the warm mission period of AKARI, 147 pointed observations were performed for 66 asteroids in the grism mode for wavelengths from 2.5 to 5 µm. According to these observations, most C-complex asteroids have clear absorption features (> 10% with respect to the continuum) related to hydrated minerals at a peak wavelength of approximately 2.75 µm, while S-complex asteroids have no significant feature in this wavelength range. The present data are released to the public as the Asteroid Catalog using AKARI Spectroscopic Observations (AcuA-spec).

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Section: Thermal Component Subtractionmentioning

confidence: 99%

AKARI/IRC near-infrared asteroid spectroscopic survey: AcuA-spec

Usui

Hasegawa

Ootsubo

et al. 2018

Publications of the Astronomical Society of Japan

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“…It seems that Wilson-Harrington's phase curve coefficient is easily compatible with other comets or with asteroids that it might be dynamically linked to. Wilson-Harrington's thermal inertia and albedo are both also compatible with a possible cometary or asteroidal nature (Licandro et al 2009;Bach et al 2017), highlighting the challenges with clearly discerning the origin of low-albedo objects generally-a topic we return to in Section 4.…”

Section: Phase Curves From Atlasmentioning

confidence: 97%

“…If we assume that Wilson-Harrington originally had a traditional comet reflectance spectrum, then there are many objects that are currently classified as asteroids that may actually trace their origins back to the TNOs rather recently. These would likely be low-albedo asteroids with red reflectance spectra (but not as red as comet nuclei), with similar phase curves and thermal inertias (Bach et al 2017) to comets and low-albedo asteroids, and are in orbits that are not exclusively cometary (e.g., T J around or slightly above ∼3.0). The general agreement between NEO origin models and the known NEOs about what fraction of the population might be dormant comets (a few percent; Bottke et al 2002;Granvik et al 2018) suggests that these hidden comets should not be too large in number.…”

Section: Scenario 1: Unknown Cometary Surface Alteration Processmentioning

confidence: 99%

Nuclear and Orbital Characterization of the Transition Object (4015) 107P/Wilson–Harrington

Kareta,

Reddy

2023

Planet. Sci. J.

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Comet 107P/Wilson–Harrington, cross-listed as asteroid 4015, is one of the original transition objects whose properties do not neatly fit into a cometary or asteroidal origin. Discovered in a period of apparently gas-dominated activity in 1949, it was subsequently lost and recovered as the inactive asteroid 1979 VA. We obtained new and reanalyzed archival observations of the object, compared to meteorites, and conducted new orbital integrations in order to understand the nature of this object and to understand where it falls on the asteroid–comet continuum. Wilson–Harrington’s reflectance spectrum is approximately neutral from visible to near-infrared wavelengths, but has a reflectance maximum near 0.8–0.9 μm. The object’s spectrum is well matched by laboratory spectra of carbonaceous chondrite meteorites like the CM Murchison or the C i Ivuna. The object’s phase curve slope is compatible with either an asteroidal or cometary origin, and its recent orbital history has no periods with high enough temperatures to have altered its surface. While it is possible that some unknown process has acted to change the surface from an originally cometary one, we instead prefer a fundamentally asteroidal origin for Wilson–Harrington, which can explain its surface and orbital properties. However, this would require a way to maintain significant (hyper)volatile supplies on the near-Earth objects beyond what is currently expected. Wilson–Harrington’s similar meteorite affinity and possible orbital link to sample return targets (162173) Ryugu and (101955) Bennu suggest that the returned samples from the Hayabusa-2 and OSIRIS-REx missions might hold the key to understanding this object.

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Thermal properties of large main-belt asteroids observed byHerschelPACS

Alí-Lagoa

Müller

Kiss

et al. 2020

A&A

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Non-resolved thermal infrared observations enable studies of thermal and physical properties of asteroids via thermo-physical models provided the shape and rotational properties of the target are well determined. We used calibration-programme Herschel PACS data (70, 100, 160 μm) and state-of-the-art shape models derived from adaptive-optics observations and/or optical light curves to constrain for the first time the thermal inertia of twelve large main-belt asteroids. We also modelled previously well-characterised targets such as (1) Ceres or (4) Vesta as they constitute important benchmarks. Using the scale as a free parameter, most targets required a re-scaling ~5% consistent with what would be expected given the absolute calibration error bars. This constitutes a good cross-validation of the scaled shape models, although some targets required larger re-scaling to reproduce the IR data. We obtained low thermal inertias typical of large main belt asteroids studied before, which continues to give support to the notion that these surfaces are covered by fine-grained insulating regolith. Although the wavelengths at which PACS observed are longwards of the emission peak for main-belt asteroids, they proved to be extremely valuable to constrain size and thermal inertia and not too sensitive to surface roughness. Finally, we also propose a graphical approach to help examine how different values of the exponent used for scaling the thermal inertia as a function of heliocentric distance (i.e. temperature) affect our interpretation of the results.

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Thermal Modeling of Comet-like Objects from AKARI Observation

Cited by 3 publications

References 55 publications

AKARI/IRC near-infrared asteroid spectroscopic survey: AcuA-spec

AKARI/IRC near-infrared asteroid spectroscopic survey: AcuA-spec

Nuclear and Orbital Characterization of the Transition Object (4015) 107P/Wilson–Harrington

Thermal properties of large main-belt asteroids observed byHerschelPACS

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