Physical Characterization of the December 2017 Outburst of the Centaur 174P/Echeclus

Abstract

The Centaurs are the small solar system bodies intermediate between the active inner solar system Jupiter Family Comets and their inactive progenitors in the trans-Neptunian region. Among the fraction of Centaurs which show comet-like activity, 174P/Echeclus is best known for its massive 2005 outburst in which a large apparently active fragment was ejected above the escape velocity from the primary nucleus. We present visible imaging and near-infrared spectroscopy of Echeclus during the first week after its December 2017 outburst taken at the Faulkes North & South Telescopes and the NASA IRTF, the largest outburst since 2005. The coma was seen to be highly asymmetric. A secondary peak was seen in the near-infrared 2D spectra, which is strongly hinted at in the visible images, moving hyperbolically with respect to the nucleus. The retrieved reflectance spectrum of Echelcus is consistent with the unobscured nucleus but becomes bluer when a wider extraction aperture is used. We find that Echeclus's coma is best explained as dominated by large blue dust grains, which agrees with previous work. We also conducted a high-resolution orbital integration of Echeclus's recent evolution and found no large orbital changes that could drive its modern evolution. We interpret the second peak in the visible and near-infrared datasets as a large cloud of larger-than-dust debris ejected at the time of outburst. If Echeclus is typical of the Centaurs, there may be several debris ejection or fragmentation events per year on other Centaurs that are going unnoticed.

arXiv commentAccepted for publication in the Astronomical Journal, 18 pages, 4 figures, 4 tables

References in corpus (20)

• IAS15: A fast, adaptive, high-order integrator for gravitational dynamics, accurate to machine precision over a billion orbits
• A ring system detected around the Centaur (10199) Chariklo
• The Active Centaurs
• Simulations of the Population of Centaurs I: The Bulk Statistics
• The Dynamics of Known Centaurs
• Color Systematics of Comets and Related Bodies
• Centaurs and Scattered Disk Objects in the Thermal Infrared: Analysis of WISE/NEOWISE Observations
• Reopening the TNOs Color Controversy: Centaurs Bimodality and TNOs Unimodality
• CO in distantly active comets
• The Bimodal Colors of Centaurs and Small Kuiper Belt Objects
• 29P/Schwassmann-Wachmann 1, A Centaur in the Gateway to the Jupiter-Family Comets
• Outburst activity in comets: II. A multi-band photometric monitoring of comet 29p/Schwassmann-Wachmann 1
• Dynamical evolution and end states of active and inactive Centaurs
• Carbon monoxide in the distantly active Centaur (60558) 174P/Echeclus at 6 AU
• 174P/Echeclus: a strange case of outburst
• The Trojan Color Conundrum
• That's the way the comet crumbles: Splitting Jupiter-family comets
• Col-OSSOS: Color and Inclination are Correlated Throughout the Kuiper Belt
• 174P/Echeclus and its Blue Coma Observed Post-outburst
• OSSOS: XV. No active Centaurs in the Outer Solar System Origins Survey

Cited by in corpus (4)

• P/2019 LD2 (ATLAS): An Active Centaur in Imminent Transition to the Jupiter Family
• The active centaur 2020 MK4
• The Discovery and Evolution of a Possible New Epoch of Cometary Activity by the Centaur (2060) Chiron
• On The Spin Dynamics of Elongated Minor Bodies with Applications to a Possible Solar System Analogue Composition for `Oumuamua