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Asteroid (142) Polana at 3 µM and Its Linkage to the Primitive Asteroid (101955) BennuThe Polana family is a low-albedo family located at a low inclination and a semimajor axis of ~2.42 au in the inner main asteroid belt. This family is likely the source of primitive near-Earth asteroids, including the OSIRIS-REx mission target (101955) Bennu. The B-type asteroid 142 Polana is the largest remnant of the "New Polana" family, and it has been spectrally (~0.5-2.5 µm) and dynamically linked to Bennu. Here, we investigate the compositional linkage of asteroids Polana and Bennu using spectra measured at longer wavelengths (~1.6-4.0 µm), which cover the 3- µm band. Polana’s spectra were measured at NASA IRTF using the LXD mode of SpeX. Bennu’s spectra were measured by OSIRIS-REx’s OVIRS spectrometer and revealed that this primitive asteroid is hydrated consistent with CM, CI, or CR carbonaceous chondrites. Polana’s LXD spectra, on the hand, show that the parent body of the Polana family is not hydrated (i.e., no absorption band at ~ 3.0 µm). Additionally, Polana’s LXD spectra do not indicate the presence of organics and/or carbonates. Polana's lack of significant water, organic, and carbonate spectral features on its surface could be related to the degree of heating in the Polana family-forming event and the reaccretion of ejecta that contributed to additional heating. The Polana family-forming event could also expose the parent body's dehydrated, organic/carbonate-poor interior. These results will be placed in the context of other low-albedo families and background objects in the inner main belt. An approved JWST program to observe Polana (with both NIRSpec and MIRI) will be able to assess if there is a Ryugu-like band and should allow a comparison of the MIR spectrum to Bennu.
Document ID
20230012648
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Driss Takir
(Jacobs (United States) Dallas, Texas, United States)
William Bottke
(Southwest Research Institute San Antonio, Texas, United States)
Joshua Emery ORCID
(Northern Arizona University Flagstaff, Arizona, United States)
Anicia Arredondo
(Southwest Research Institute San Antonio, Texas, United States)
Date Acquired
August 28, 2023
Subject Category
Astronomy
Lunar and Planetary Science and Exploration
Geosciences (General)
Meeting Information
Meeting: 55th Annual Division for Planetary Sciences (DPS) meeting joint with the Europlanet Science Congress (EPSC)
Location: San Antonio, TX
Country: US
Start Date: October 1, 2023
End Date: October 6, 2023
Sponsors: American Astronomical Society
Funding Number(s)
TASK: ES0407254100006
Distribution Limits
Public
Copyright
Portions of document may include copyright protected material.
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