Multi-year Ground-Based Survey Photometry of Active Comet 103P/Hartley 2 and Centaur (2060) Chiron: A Tale of Two Comets in the Pre-LSST Era

2026/06/29 by Joseph Murtagh, Megan E. Schwamb, Michael S. P. Kelley +22 · 1 voice
#astro-ph.EP

paper · pdf

Abstract

Comets and Centaurs trace the evolution of trans-Neptunian objects (TNOs) into the inner solar system. Their activity reflects the interplay between volatile sublimation, dust dynamics, and ring scattering. Yet the long-term behavior of individual objects is less constrained. To probe this evolutionary transition, we use wide-field survey photometry from the Asteroid Terrestrial-impact Last Alert System, Zwicky Transient Facility, and Las Cumbres Observatory observations of the Jupiter-family comet (JFC) 103P/Hartley 2 during its 2023/24 apparition, and the Centaur (2060) Chiron across 2020-2025, including its 2021 outburst. For 103P, heliocentric activity slopes are asymmetric about perihelion, with a steep inbound index (n_{r,\rm pre}=-3.48±0.08) and flatter outbound value (n_{r,\rm post}=-1.16±0.04), consistent with enhanced relative dust contribution post-perihelion. Reduced brightness versus prior apparitions matches reported secular fading trends. Dust mass-loss rates are ∼4-16 kg s^-1 for assumed grain properties. Colors exhibit a blueward trend near perihelion, consistent with enhanced gas contamination of the g-band, with possible phase-dependent scattering. A periodogram recovers a ∼18.7 hr activity-linked period near perihelion. For Chiron, subtracting a quiescent baseline reveals exponential decay from the 2021 outburst on a ∼1.4 yr timescale. Seasonal phase curves flatten from β_o=0.150±0.034 mag deg^-1 in 2021 to \lesssim0.09 mag deg^-1 by 2023-2025, converging with quiescent behavior. Broad-band colors remain unchanged at ATLAS (c-o)=0.22±0.09 mag. This extended activity suggests a new epoch of persistent, low-level activity and/or evolving ring-scattering. These objects bracket the TNO-to-JFC evolutionary sequence, with 103P near the volatile-depleted end, and Chiron still volatile-rich and capable of episodic activity.

Citations

• JWST reveals anomalously enhanced methane outgassing from below Chiron's water ice and carbon dioxide bearing surface
• Dynamical environment and stability around Centaur (2060) Chiron
• The rings of (2060) Chiron: Evidence of an evolving system
• The Ongoing Decline in Activity of Comet 103P/Hartley 2
• Dust production rates in Jupiter-family comets II: Trends and population insights from ATLAS photometry of 116 JFCs
• Predictions of the LSST Solar System Yield: Discovery Rates and Characterizations of Centaurs
• Semi-major Axis Jumps as the Activity Trigger in Centaurs and High-Perihelion Jupiter Family Comets
• Dust production rates in Jupiter-family Comets: A two-year study with ATLAS photometry
• Material Around the Centaur (2060) Chiron from the 2018 November 28 UT Stellar Occultation
• First detection of CO₂ emission in a Centaur: JWST NIRSpec observations of 39P/Oterma
• Phase Curves of Kuiper Belt Objects, Centaurs, and Jupiter Family Comets from the ATLAS Survey
• The LCO Outbursting Objects Key Project: Overview and Year 1 Status
• No Activity Among 13 Centaurs Discovered in the Pan-STARRS1 Detection\n Database
• The Zwicky Transient Facility: System Overview, Performance, and First Results
• Large Synoptic Survey Telescope Solar System Science Roadmap
• The Astropy Project: Building an Open-science Project and Status of the v2.0 Core Package^*
• The Pan-STARRS1 Surveys
• A Further Investigation of Apparent Periodicities and the Rotational State of Comet 103P/Hartley 2 from Combined Coma Morphology and Lightcurve Datasets
• Possible ring material around centaur (2060) Chiron
• LSST Science Book, Version 2.0
• Studies in astronomical time series analysis. II - Statistical aspects of spectral analysis of unevenly spaced data
• Least-squares frequency analysis of unequally spaced data

Discussions

• I need to highlight a paper from the research group led by former PhD student Joe Murtagh Multi-year Ground-Based Survey Photometry of Active Comet 103P/Hartley 2 and Centaur (2060) Chiron: A Tale of [bsky, 6 points, 0 comments]

Related

• The Discovery and Evolution of a Possible New Epoch of Cometary Activity by the Centaur (2060) Chiron
• The Ongoing Decline in Activity of Comet 103P/Hartley 2
• Analysing the Onset of Cometary Activity by the Jupiter-Family Comet 2023 RN3
• Dust production rates in Jupiter-family Comets: A two-year study with ATLAS photometry
• Dust production rates in Jupiter-family comets II: Trends and population insights from ATLAS photometry of 116 JFCs