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Monitoring Centaur 29P/S-W1: Outburst history, rise-time kinetics, inner coma dynamics and fallback phenomena

Presentation #414.03 in the session Centaurs and KBOs: Observational Surveys (iPosters).

Published onOct 20, 2022
Monitoring Centaur 29P/S-W1: Outburst history, rise-time kinetics, inner coma dynamics and fallback phenomena

A Cousins R photometric observing campaign [1] monitoring Comet 29P/S-W1 from 2014 to 2022 has identified more than 160 outbursts (median timing accuracy, 0.18 days); this apparent outburst rate is almost three times greater than previously recognised. Outbursts exhibited a bi-modal distribution in terms of their relative intensity and seasonal dependence. Strong outbursts generate an expanding coma, the projected area of which ranges from 4–300 nucleus-equivalents (65 events) and confirm the 57.7-day periodicity proposed previously [2]. Modelling and coma morphology indicate strong outbursts often occur near the morning terminator. Ninety-six weaker events or mini-outbursts, undetected prior to 2014, were identified ranging in intensity from 0.2–4 nucleus-equivalents; these show a different seasonal variability and may be caused by a different underlying phenomenon. Both types are sudden, singular events, which according to our proposed outburst model, eject material for only a short time interval of <100 s (and possibly <30 s) after which activity at the nucleus is quenched. We show that Multi-Aperture Absolute Photometry (MAAP) is a powerful tool for studying the inner coma, and provides incontrovertible evidence of gravitationally-induced fallback of material. Hubble Space Telescope publicly-available images of 29P (WFC3/F689M filter) from 2021 have provide the ‘ground truth’ for contemporaneous inner-coma photometry of images from ground-based 2.0-m telescopes of the Las Cumbres Observatory. The coma within 1000-km radius of the nucleus appears to be particularly dynamically active and often contains transient material in meta-stable orbits close to the nucleus.

References:

[1] https://britastro.org/section_information_/comet-section-overview/mission-29p-centaur-comet-observing-campaign

[2] Miles, R., 2016, Icarus 272, 387–413

Acknowledgements:

The main author utilised photometric software, AstPhot32 (v4.57) written by Stefano Mottola to perform multi-aperture photometry, and Astrometrica (v.442) written by Herbert Raab for field star calibration using UCAC-4 as the reference catalogue.

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