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arXiv · 2206.07703

Hubble Space Telescope Observations of Active Asteroid P/2020 O1 (Lemmon-PANSTARRS)

Yoonyoung Kim·David Jewitt·Jessica Agarwal·Max Mutchler·Jing Li·Harold Weaver
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Abstract

We present Hubble Space Telescope observations of active asteroid P/2020 O1 taken to examine its development for a year after perihelion. We find that the mass loss peaks <~1 kg/s in 2020 August and then declines to nearly zero over four months. Long-duration mass loss (~180 days) is consistent with a sublimation origin, indicating that this object is likely an ice-bearing main-belt comet. Equilibrium sublimation of water ice from an area as small as 1580 m^2 can supply the observed mass loss. Time-series photometry shows tentative evidence for extremely rapid rotation (double-peaked period < 2 hr) of the small nucleus (effective radius ~420 m). Ejection velocities of 0.1 mm particles are comparable to the 0.3 m/s gravitational escape speed from the nucleus, while larger particles are ejected at speeds less than the escape velocity. These properties are consistent with the sublimation of near-surface ice aided by centripetal acceleration. If water ice sublimation is confirmed, P/2020 O1 would be the icy asteroid with the smallest semimajor axis (highest temperature), setting new bounds on the distribution of ice in the asteroid belt.

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Yoonyoung Kim, David Jewitt, Jessica Agarwal, Max Mutchler, Jing Li, Harold Weaver. 2022-06-15. Hubble Space Telescope Observations of Active Asteroid P/2020 O1 (Lemmon-PANSTARRS). https://doi.org/10.3847/2041-8213%2Fac78de

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