Origin and evolution of long-period comets

Abstract

We develop an evolutionary model of the long-period comet (LPC) population, starting from their birthplace in a massive trans-Neptunian disk that was dispersed by migrating giant planets. Most comets that remain bound to the Solar system are stored in the Oort cloud. Galactic tides and passing stars make some of these bodies evolve into observable comets in the inner Solar system. Our approach models each step in a full-fledged numerical framework. Subsequent analysis consists of applying plausible fading models and computing the original orbits to compare with observations. Our results match the observed semimajor axis distribution of LPCs when Whipple's power-law fading scheme with an exponent $\kappa =0.6_{-0.2}^{+0.1}$ is adopted. The cumulative perihelion ($q$) distribution is fit well by a linear increase plus a weak quadratic term. Beyond $q=15$~au, however, the population increases steeply and the isotropy of LPC orbital planes breaks. We find tentative evidence from the perihelion distribution of LPCs that the returning comets are depleted in supervolatiles and become active due to water ice sublimation for $q\le 3$ au. Using an independent calibration of the population of the initial disk, our predicted LPC flux is smaller than observations suggest by a factor of $\simeq 2$. Current data only characterize comets from the outer Oort cloud (semimajor axes $\gtrsim 10^4$~au). A true boost in understanding the Oort cloud's structure should result from future surveys when they detect LPCs with perihelia beyond $15$~au. Our results provide observational predictions of what can be expected from these new data.

35 pages, 22 figures, AAS journals in press

References in corpus (27)

• Riding the Spiral Waves: Implications of Stellar Migration for the Properties of Galactic Disks
• On the local dark matter density
• The Planet Nine Hypothesis
• Origin and Evolution of Short-Period Comets
• Sedna and the Oort Cloud Around a Migrating Sun
• The Formation of the Oort Cloud in Open Cluster Environments
• Injection of Oort Cloud Comets: The Fundamental Role of Stellar Perturbations
• OSSOS VI. Striking Biases in the detection of large semimajor axis Trans-Neptunian Objects
• The formation of the solar system
• Tracking Neptune's Migration History through High-Perihelion Resonant Trans-Neptunian Objects
• Generation of Highly Inclined Trans-Neptunian Objects by Planet Nine
• Solar Obliquity Induced by Planet Nine
• Oort spike comets with large perihelion distances
• The orbital distribution of trans-Neptunian objects beyond 50 au
• The inclination of the planetary system relative to the solar equator may be explained by the presence of Planet 9
• Near-parabolic comets observed in 2006-2010. II. Their past and future motion under the influence of the Galaxy field and known nearby stars
• The completeness-corrected rate of stellar encounters with the Sun from the first Gaia data release
• Small Jupiter Trojans Survey with Subaru/Hyper Suprime-Cam
• Orbital clustering in the distant solar system
• Capture of exocomets and the erosion of the Oort cloud due to stellar encounters in the Galaxy
• The rate of stellar encounters along a migrating orbit of the Sun
• The effect of the Solar motion on the flux of long-period comets
• Where do long-period comets come from? 26 comets from the non-gravitational Oort spike
• Hektor - an exceptional D-type family among Jovian Trojans
• Solar Obliquity Induced by Planet Nine: Simple Calculation
• Warsaw Catalogue of cometary orbits: 119 near-parabolic comets
• Modeling the Nearly Isotropic Comet Population in Anticipation of LSST Observations

Cited by in corpus (11)

• Solar System Physics for Exoplanet Research
• Long-term orbital dynamics of trans-Neptunian objects
• Oort cloud Ecology II: The chronology of the formation of the Oort cloud
• Initial Characterization of Active Transitioning Centaur, P/2019 LD2 (ATLAS), using Hubble, Spitzer, ZTF, Keck, APO and GROWTH Visible & Infrared Imaging and Spectroscopy
• Capture of interstellar objects: a source of long-period comets
• The stability in the most external region of the Oort Cloud: The evolution of the ejected comets
• Breakup of a Long-Period Comet as the Origin of the Dinosaur Extinction
• Exogenous delivery of water to Mercury
• A LOOK at Outbursts of Comet C/2014 UN${}_{271}$ (Bernardinelli-Bernstein) Near 20 au
• The influence of individual stars on the long-term dynamics of comets C/2014 UN271 and C/2017 K2
• Retrograde orbits excess among observable interstellar objects