Issue |
A&A
Volume 666, October 2022
|
|
---|---|---|
Article Number | A163 | |
Number of page(s) | 8 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202244356 | |
Published online | 25 October 2022 |
Sublimation origin of active asteroid P/2018 P3
1
Institute for Geophysics and Extraterrestrial Physics,
TU Braunschweig,
38106
Braunschweig, Germany
e-mail: yoonyoung.kim@tu-bs.de
2
Max Planck Institute for Solar System Research,
37077
Göttingen, Germany
3
Department of Earth, Planetary and Space Sciences, UCLA,
Los Angeles, CA
90095-1567, USA
4
Space Telescope Science Institute,
Baltimore, MD
21218, USA
5
Lunar and Planetary Laboratory, University of Arizona,
Tucson, AZ
85721-0092, USA
6
The Johns Hopkins University Applied Physics Laboratory,
Laurel, MD
20723, USA
7
University of St. Gallen, Institute of Computer Science,
9000
St. Gallen, Switzerland
Received:
27
June
2022
Accepted:
15
August
2022
Context. Active asteroids show (typically transient) cometary activity, driven by a range of processes. A sub-set, sometimes called main-belt comets, may be driven by sublimation and so could be useful for tracing the present-day distribution of asteroid ice. Object P/2018 P3 has a Tisserand parameter 3.096 but a high eccentricity 0.415, placing it within the dynamical boundary between asteroids and comets.
Aims. We aim to determine the cause of activity (sublimation or something else) and assess the dynamical stability of P3, in order to better constrain the intrinsic ice content in the main belt.
Methods. We obtained Hubble Space Telescope images of P3 at the highest angular resolution. We compared the observations with a Monte Carlo model of dust dynamics. We identified and analyzed archival CFHT (2013) and NEOWISE (2018) data. In addition, we numerically integrated the orbits of P3 clones for 100 Myr.
Results. Object P3 has been recurrently active near two successive perihelia (at 1.76 AU), indicative of a sublimation origin. The absence of 4.6 µm band excess indicates zero or negligible CO or CO2 gas production from P3. The properties of the ejected dust are remarkably consistent with those found in other main-belt comets (continuous emission of ~0.05–5 mm particles at 0.3–3 m s−1 speeds), with mass-loss rates of ≳2 kg s−1. The orbit of P3 is unstable on timescales ~ 10 Myr.
Conclusions. We speculate that P3 has recently arrived from a more stable source (either the Kuiper Belt or elsewhere in the main belt) and has been physically aged at its current location, finally becoming indistinguishable from a weakly sublimating asteroid in terms of its dust properties. Whatever the source of P3, given the dynamical instability of its current orbit, P3 should not be used to trace the native distribution of asteroid ice.
Key words: minor planets, asteroids: general / minor planets, asteroids: individual: P/2018 P3 / comets: general
© Y. Kim et al. 2022
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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