Recurring Activity Discovered on Quasi-Hilda 2009 DQ118

Abstract

We have discovered two epochs of activity on quasi-Hilda 2009 DQ118. Small bodies that display comet-like activity, such as active asteroids and active quasi-Hildas, are important for understanding the distribution of water and other volatiles throughout the solar system. Through our NASA Partner Citizen Science project, Active Asteroids, volunteers classified archival images of 2009 DQ118 as displaying comet-like activity. By performing an in-depth archival image search, we found over 20 images from UT 2016 March 8–9 with clear signs of a comet-like tail. We then carried out follow-up observations of 2009 DQ118 using the 3.5 m Astrophysical Research Consortium Telescope at Apache Point Observatory, Sunspot, New Mexico, USA and the 6.5 m Magellan Baade Telescope at Las Campanas Observatory, Chile. These images revealed a second epoch of activity associated with the UT 2023 April 22 perihelion passage of 2009 DQ118. We performed photometric analysis of the tail and find that it had a similar apparent length and surface brightness during both epochs. We also explored the orbital history and future of 2009 DQ118 through dynamical simulations. These simulations show that 2009 DQ118 is currently a quasi-Hilda and that it frequently experiences close encounters with Jupiter. We find that 2009 DQ118 is currently on the boundary between asteroidal and cometary orbits. Additionally, it has likely been a Jupiter family comet or Centaur for much of the past 10 kyr and will be in these same regions for the majority of the next 10 kyr. Since both detected epochs of activity occurred near perihelion, the observed activity is consistent with sublimation of volatile ices. 2009 DQ118 is currently observable until ∼mid-October 2023. Further observations would help to characterize the observed activity.

The Active Asteroids Citizen Science Program: Overview and First Results

“…In total, our program has yielded 14 new active objects, comprising one active Centaur, C/2014 OG 392 (PANSTARRS; Chandler et al 2020); four active asteroids and MBC candidates (Section 7.2.1), 2007 FZ 18 (Chandler et al 2023a), 2010 LH 15 (Chandler et al 2023b), 2015 FW 412 (Chandler et al 2023c), and 2015 VA 108 (Chandler et al 2023d); four active QHAs (Section 7.2.2): 2004 CV 50 (Chandler et al 2023h), 2009 (Oldroyd et al 2023a(Oldroyd et al , 2023b, 2018 CZ 16 (Trujillo et al 2023) (Chandler et al 2022), all of which are summarized in Table 3.…”

“…b Section 7.2.3: 2000 AU 242 (Chandler 2022), 2005 XR 132 (Cheng et al 2021b; Chandler et al 2023f), 2008 QZ 44 (Chandler et al 2023g), 2012 UQ 192 (DeSpain et al 2023), 2015 TC 1 (Chandler 2022), 2017 QN 84 (Chandler 2022), 2018 OR (Farrell et al 2024), 2018 VL 10 (Chandler et al 2023i). Section 7.2.2: 282P (Chandler et al 2022), 2004 CV 50(Chandler et al 2023e), 2009 (Oldroyd et al 2023a(Oldroyd et al , 2023b, 2018 CZ 16(Trujillo et al 2023…”