Details

Autor(en) / Beteiligte

• Pokorný, Petr
• Kuchner, Marc

Titel

Threat from Within: Excitation of Venus’s Co-orbital Asteroids to Earth-crossing Orbits

Ist Teil von

• The planetary science journal, 2021-10, Vol.2 (5), p.193

Ort / Verlag

The American Astronomical Society

Erscheinungsjahr

2021

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Abstract All five currently known asteroids in the 1:1 mean-motion resonance (co-orbital) with Venus cross Earth’s orbit. We explore a scenario in which these near-Earth asteroids originate in a reservoir of asteroids co-orbiting with Venus on low-eccentricity orbits. Such an asteroid reservoir was proposed as the only viable source of Venus’s co-orbital dust ring. So far, efforts to discover low-eccentricity Venus co-orbital (LEVCO) asteroids have been unsuccessful; however, their existence has not been ruled out. We show that LEVCO asteroids, stable for millions to billions of years, eventually evolve into Earth-crossing configurations, where they may pose a threat to Earth. We find that the orbits of these asteroids cross Earth’s orbit for 22.5 million yr, on average, an order of magnitude longer than the corresponding Earth-crossing time of most asteroids escaping from the main belt. Using the results of the latest survey of LEVCO asteroids, we conclude that, given their absolute magnitudes, H , most of the observed Venus co-orbitals likely do not originate from the hypothetical population of LEVCO asteroids. However, we infer that there are up to ∼500 asteroids originating from the LEVCO region with H < 26.3 (10–40 m in diameter) that currently cross the orbit of Earth. Up to ∼20 of those have H < 24.1 (30–100 m in diameter), easily detectable by various near-Earth asteroid surveys. We estimate the current mass of the LEVCO reservoir as M ≈ 10 13 –10 16 kg, 3–6 orders of magnitude lower than the current mass of the main belt, depending on their size–frequency distribution.