Photometric and dynamic characterization of active asteroid (248370) 2005QN173

Abstract

We present the physical and dynamical properties of the recently discovered active asteroid (248370) 2005QN173 (aka 433P). From our observations, we derived two possible rotation period solutions 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. Both period solutions are shorter than the critical rotation limit computed for a strengthless triaxial ellipsoid, suggesting that rotation mass shedding should at least partly be responsible for the observed activity. We confirm that the activity level is fading further, but at a very modest rate of only 0.006 mag/day, still also compatible with sublimation-driven activity. We found that 248370 likely belongs to the Themis asteroid family, making it a fourth main-belt comet associated with this group. Orbital characteristics of 248370 are also consistent with its origin in the young 288P cluster of asteroids. The 288P cluster is associated with its namesake main-belt comet, providing an exciting possibility for a comparative analysis of intriguing main-belt comets 248370 and 288P.

Observational Characterization of Main-belt Comet and Candidate Main-belt Comet Nuclei

“…However, dust-modeling results indicate low dust ejection speeds for many of these objects, suggesting that centrifugal forces from rapid rotation may facilitate the escape of particles that may not otherwise be ejected at velocities large enough to exceed each object's surface gravity (e.g., Jewitt et al 2014b). This possibility is supported by direct evidence of rapid rotation in several MBCs with slow estimated dust ejection velocities, including 133P (Hsieh et al 2004), 427P (Jewitt et al 2019), 433P (Novaković et al 2022), and P/2020 O1 (Kim et al 2022). There may also be other fast-rotating MBCs that have not yet been identified as such, given the difficulty of measuring rotation rates of such faint targets, where only one MBC, 176P, has actually been confirmed to date to have a slow rotation rate (P rot = 22.23 hr; Hsieh et al 2011a).…”

Observational Characterization of Main-Belt Comet and Candidate Main-Belt Comet Nuclei

“…However, dust modeling results indicate low dust ejection speeds for many of these objects, suggesting that centrifugal forces from rapid rotation may facilitate the escape of particles that may not otherwise be ejected at velocities large enough to exceed each object's surface gravity (e.g., Jewitt et al 2014b). This possibility is supported by direct evidence of rapid rotation in several MBCs with slow estimated dust ejection velocities, including 133P (Hsieh et al 2004), 427P (Jewitt et al 2019), 433P (Novaković et al 2022), and P/2020 O1 (Kim et al 2022). There may also be other fastrotating MBCs that have not yet been identified as such, given the difficulty of measuring rotation rates of such faint targets, where only one MBC, 176P, has actually been confirmed to date to have a slow rotation rate (P rot = 22.23 h; Hsieh et al 2011a).…”