Characterisation of active asteroid (248370) 2005QN173
- 1University of Belgrade, Faculty of Mathematics, Department of Astronomy, Belgrade, Serbia (bojan@matf.bg.ac.rs)
- 2Planetary Science Institute, 1700 East Fort Lowell Rd., Suite 106, Tucson, AZ 85719, USA
- 3Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan
1. INTRODUCTION
Active asteroids are small solar system bodies, having at the same time the orbital characteristics of asteroids but showing the physical characteristics of comets, including coma and tail-like appearance. A subpopulation of active asteroids that have sublimation as the main source of activity is known as main-belt comets (MBCs, [6]). The MBCs could be a key to tracing the origin and evolution of volatile materials in the asteroid belt and could help our understanding of the protoplanetary disk process and planetary formation. The number of known MBCs is, however, still relatively small. For this reason, the characterisation of new objects is of considerable importance.
This work analyses active asteroid (248370) 2005QN173, (aka 433P). Its activity was recently discovered by Fitzsimmons et al. [4] in the images collected by the Asteroid-Terrestrial-Impact Last Alert System (ATLAS;[11]). Based on the recurrent activity, Chandler et al. [3] suggested that activity is sublimation-driven, making asteroid 248370 a main-belt comet. Aiming to constrain possible activity mechanisms further, we performed photometric observations of 248370. Our primary goals are to quantify the activity level variation and determine the rotation period. The activity changes could help better understand what is driving the activity. Similarly, the rotation period provides a clue on a possible mass shedding due to rotational instabilities. Furthermore, we also analysed its dynamical stability in order to get insights into the past orbit evolution. Finally, we investigated its possible association with asteroid families.
2. OBSERVATIONS
Observations of the 248370 were collected on 2021 October 5/6 from the Astronomical station Vidojevica (C89), using a 1.4 m Milanković telescope. All images were made in standard Johnson-Cousin R-filter.
Figure 1: Field of view for one of the images of the active asteroid 248730.
3. ROTATIONAL PERIOD
Image processing, measurement, light curve construction and period analysis were done using procedures incorporated into the MPO Canopus2 [10]. In particular, the period analysis is performed using the Fourier analysis algorithm developed by Harris et al.[5].
Unfortunately, we were not able to find a unique rotational period solution. Instead, we derived two possible periods of 2.7±0.1 and 4.1±0.1 hours. The corresponding light-curve amplitudes computed after correcting for the effect of coma are 0.28 and 0.58 mag, respectively. An example of the obtained light-curve of 248370, along with a fit corresponding to the period solution of 2.7±0.1 h, is shown in Figure 2.