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EP: Fachverband Extraterrestrische Physik
EP 7: Planets and Small Bodies III
EP 7.3: Vortrag
Mittwoch, 2. April 2025, 11:30–11:45, ZHG005
"Dark Comets" among the Near-Earth Asteroids — •Jessica Agarwal1, Nicholas Attree2, Pedro Gutierrez2, Oriel Humes1, and Manuela Lippi3 — 1TU Braunschweig, Germany — 2Instituto de Astrofisica de Andalucia, Granada, Spain — 3INAF, Osservatorio astrofisico di Arcetri, Firenze, Italy
The "dark comets" are a handful of near-Earth asteroids (NEAs) that have their orbits perturbed by a non-gravitational acceleration inconsistent with radiative processes of momentum transfer like radiation pressure and the Yarkowsky effect (Seligman et al., 2023, 2024, Farnocchia et al. 2023).
Asymmetric outgassing has been suggested as the next straightforward explanation of this acceleration, despite, but not inconsistent with a non-detection of emitted dust. Taylor et al. (2024) propose a model where the sublimating region would be located near the poles, and the rotation axes of the "dark comets" would have to be highly tilted. Thermophysical models (e.g., Schoerghofer & Hsieh, 2018), however, predict that, if at all, ice can be preserved in asteroids this close to the sun only in permanently shadowed polar regions, requiring a near-zero tilt.
This contribution reviews the available evidence concerning the "dark comets" and discusses the implications for the distribution and preservation of volatiles (i.e. water ice) in the asteroid population.
References: Seligman et al. (2023), PSJ, 4, 35; Seligman et al (2024) PNAS, 121, 51; Farnocchia et al. (2023), PSJ, 4, 29; Schoerghofer & Hsieh (2018), JGRP, 123, 2322.
Keywords: asteroids; comets