Isolating the mechanisms for asteroid surface refreshing
نویسندگان
چکیده
Evidence is seen for young, fresh surfaces among Near-Earth and Main-Belt asteroids even though space-weathering timescales are shorter than the age of surfaces. A number mechanisms have been proposed to refresh asteroid on short timescales, such as planetary encounters, YORP spinup, thermal degradation, collisions. Additionally, other factors grain size effects explain existence these “fresh-looking” spectra. To investigate role each may play, we collected a sample visible near-infrared spectra 477 near-Earth Mars Crosser with similar sizes compositions — all absolute magnitude H > 16 within S-complex having olivine pyroxene (ol/(ol+opx)) ratios >0.65. We taxonomically classify objects in Q (fresh) S (weathered) classes. find four trends Q/S ratio: (1) previous work demonstrated ratio increases at smaller down ≲16, but sharp increase near H∼19 after which decreases monotonically. (2) agreement many studies, decreasing perihelion distance, it non-zero larger perihelia >1.2AU, (3) new finding our reveals has sharp, significant peak ∼5° orbital inclination, (4) confirm findings that higher possibility encounter Earth Venus versus those do not, however this cannot be distinguished from trend. No single resurfacing mechanism can trends, so multiple required. spin-up scales size, degradation dependent perihelion, encounters trend MOID, noting asteroid–asteroid collisions also inclination. It likely combination needed account observational trends.
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ژورنال
عنوان ژورنال: Icarus
سال: 2023
ISSN: ['0019-1035', '1090-2643']
DOI: https://doi.org/10.1016/j.icarus.2022.115264