Dust emission by middle main-belt asteroid P/2023 JN16

The middle main-belt asteroid P/2023 JN16 was reported to have emitted a significant quantity of dust in spring 2023 (Deen et al., 2024; Ly et al. 2024), and has shown a debris trail at least until the end of 2024. This combination of comet-like dust emission and an asteroidal orbit makes it a member of the group of "active asteroids" (e.g., Jewitt et al., 2015).

A sub-group of the active asteroids are the "main-belt comets" (MBCs), the dust emission of which recurs at subsequent perihelia and is driven by the sublimation of water ice (Hsieh & Jewitt, 2006). Water ice cannot remain on the surfaces of main-belt asteroids on solar-system-age timescales and therefore, if present, must have been shielded from sunlight by, e.g., a dust cover (e.g., Schorghofer, 2008). It is thought that impulsive events like impacts or landslides can locally remove this cover and thus trigger the sublimation-driven activity of MBCs. However, recurrent perihelion sublimation and a preceding potential trigger event have not yet been observed in the same object.

The reported 2023 dust emission took place at a true anomaly around 215deg, when JN16 was just returning from aphelion, rendering ice-sublimation an unlikely cause of this activity. However, the 2023 event might have uncovered potential ice that should have sublimated during the subsequent perihelion passage of JN16, which was on 30 December 2024.

We here report on imaging data obtained with the ESO/VLT/FORS2 in December 2024 to investigate the debris cloud and to search for a potential re-activation of JN16. We estimate the size and mass of debris remaining from the 2023 event taking into account the effect of solar radiation pressure, and the size of the largest fragment. We report on the search for a fresh debris tail that would result from sublimation-driven activity, and discuss the result in the context of the water ice content of JN16.

References:

Deen, S., Collaboration, Z. T. F., Helou, G., et al. 2024, Minor Planet Electronic Circulars, 2024-Q04
Hsieh, H. H. & Jewitt, D. 2006, Science, 312, 561
Jewitt, D., Hsieh, H., & Agarwal, J. 2015, in Asteroids IV, ed. P. Michel, F. E. DeMeo, & W. F. Bottke, 221–241
Ly, K., Schnabel, A., Deen, S., et al. 2024, Central Bureau Electronic Telegrams, 5430, 1
Schorghofer, N. 2008, ApJ, 682, 697