The Splitting of Double-component Active Asteroid P/2016 J1 (PANSTARRS)

Abstract

We present deep imaging observations, orbital dynamics, and dust tail model analyses of the double-component asteroid P/2016 J1 (J1-A and J1-B). The observations were acquired at the Gran Telescopio Canarias (GTC) and the CanadaFrance-Hawaii Telescope (CFHT) from mid March to late July, 2016. A statistical analysis of backward-in-time integrations of the orbits of a large sample of clone objects of P/2016 J1-A and J1-B shows that the minimum separation between them occurred most likely ∼2300 days prior to the current perihelion passage, i.e., during the previous orbit near perihelion. This closest approach was probably linked to a fragmentation event of their parent body. Monte Carlo dust tail models show that those two components became active simultaneously ∼250 days before the current perihelion, with comparable maximum loss rates of ∼0.7 kg s −1 and ∼0.5 kg s −1 , and total ejected masses of 8×10 6 kg and 6×10 6 kg for fragments J1-A and J1-B, respectively. In consequence, the fragmentation event and the present dust activity are unrelated. The simultaneous activation times -4 -of the two components and the fact that the activity lasted 6 to 9 months or longer, strongly indicate ice sublimation as the most likely mechanism involved in the dust emission process.

Active Asteroid P/2017 S5 (ATLAS)

“…Nevertheless, the derived rate is very comparable to the mass loss rates inferred in other active asteroids using dust photometry (Jewitt et al 2015). Most interestingly, the low-speed ejection of large particles, the few kg s −1 mass-loss rate and the ∼10 2 day duration of activity are similar to these quantities measured in the dynamically related, sub-kilometer split active asteroid P/2016 J1-A, J1-B (Moreno et al 2017, Hui et al 2017).…”

“…Production rates, 1 kg s −1 , and ejection speeds, ∼0.5 m s −1 , were also comparable (Moreno et al 2017, Hui et al 2017. A plausible interpretation is that S5 is another fragment of the Theobalda parent body that has been able to retain sub-surface ice since the disruption event and which was recently triggered either by a small impact, a landslide or another surface instability.…”

Characterization of the Nucleus, Morphology, and Activity of Interstellar Comet 2I/Borisov by Optical and Near-infrared GROWTH, Apache Point, IRTF, ZTF, and Keck Observations

“…The activity of 2I can possibly be used to distinguish between the "large" or "small" size estimates for 2I discussed in Section 3.5, especially in comparison to 1I, by constraining the effect of nongravitational forces due to outgassing on its orbital trajectory. Moderate nongravitational force parameters have been measured for the orbit of 2I in prediscovery data when the comet's activity was weaker (Ye et al 2020), as has been done for solar system comets (e.g., Moreno et al 2017). If 2I has a similar size as 1I, then its small total volume and mass mean that it could also be accelerated much more by nongravitationally outgassing jet forces compared to 1I, given the apparent much larger outgassing rate for 2I than 1I.…”

The Main Belt Comets and ice in the Solar System

“…The discovery rate has increased Jewitt et al (2015c): P/2015 X6 (PANSTARRS), and P/2016 J1 (PANSTARRS), both discovered by the Pan-STARRS survey at Haleakala, Hawaii. P/2016 J1 is particularly interesting as it was observed to split into two pieces Moreno et al 2017), and its current activity perhaps was triggered by a small impact, whereby formerly buried ice started sublimating and the torque rapidly drove the parent to fragment . It reinforces the idea that rotational instability is one of the important fates that comets may suffer, especially for those sub-kilometre sized.…”