Sublimation origin of active asteroid P/2018 P3

Abstract

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. 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 CO 2 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.

Postperihelion Cometary Activity on the Outer Main-belt Asteroid 2005 XR132

“…This result is consistent with the in situ measurement obtained with the GIADA instrument on board the Rosetta spacecraft of a dust coma dominated by >0.1 mm dust grains (Della Corte et al 2019). Ground-based optical observations also support millimeter-sized dust grains that can be generally observed around various types of comets, such as the Jupiter-family Comet (JFC; Ishiguro et al 2016), the Mainbelt Comet (MBC; Kim et al 2022), and even the Long-period Comet (LPC; Hui et al 2023). According to the synchrone curves, the oldest dust ejecta is best fitted with the 120-140 day trails in our LOT discovery image obtained on April 5, indicating the cometary activity had begun shortly after the 2020 perihelion return.…”

Activity Analysis on 68P/Klemola and 78P/Gehrels 2 in 2018–2020 Perihelion Passage

“…This analysis may also provide an explanation of the cometʼs current physical properties and activity. Due to the chaotic nature of the orbit, an accurate result is impossible to obtain, but statistical analysis is still reliable with multiple clones released with slightly different initial orbital elements of the original comet (Kim et al 2022). To determine the dynamical history of 68P and 78P, we use the Bulirsch-Stoer integrator in Mercury N-body integration package version 6.2 (Chambers 1999).…”