Long-term activity of asteroid (248370) 2005 QN173.
Authors:
Oleksandra Ivanova, H. Licandro, F. Moreno, I. Lukyanyk, J. Markkanen, D. Tomko, M. Husarik, A. Cabrera-Lavers, M. Popescu, E. Shablovinska, O.Shubina
Image & caption:
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Image caption::
The g-r color map of the asteroid (248370) 2005 QN173 was observed on July 16 and October 8, 2021.
Description:
The study of active asteroids has specificities, unlike comets, particularly the extremely rare observations. The activity of asteroids is virtually always unexpected and cannot be predicted, unlike comets, which show a long-term and usually slow change in gas-dust activity. Observations of active asteroids can often only be made over a limited time interval due to the relatively short duration of the phenomenon (coma and tail formation) and also due to the low brightness, and are mostly accessible mainly to larger telescopes.
Polarimetric images of asteroid (248370) 2005 QN173 were acquired for the first time during its activity period from July 2021 to January 2022. Detailed maps of the spatial distribution of color and linear polarization around the asteroid's core and tail were constructed. Analysis of these distributions revealed significant changes in polarization and color along the tail. The average values of polarization and color were found to be typical of C-type asteroids. Analysis of the spectral observations showed the absence of emission characteristics of gaseous components. The total mass of the ejected dust was estimated to be 4.2 × 10^7 kg based on Monte Carlo modelling of the dust tail. The size of the asteroid was estimated to be 1.3 km. Modelling of the dust component based on polarimetric and photometric data suggested that large particles are concentrated around the nucleus while smaller particles dominate the tail. The orbital evolution of the asteroid and the orbits of 464 short-period comets were also investigated, showing that 10 of them approached the asteroid's orbit during its period of activity. It was shown that these objects are not genetically related despite the very close proximity of their orbits over a relatively long period.
Reference:
Monthly Notices of the Royal Astronomical Society, 525, 1, 402-414 (2023).
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