A link between the size and composition of comets
arXiv:2403.15644 · doi:10.1093/mnras/stae881
Abstract
All cometary nuclei that formed in the early Solar System incorporated radionuclides and therefore were subject to internal radiogenic heating. Previous work predicts that if comets have a pebble-pile structure internal temperature build-up is enhanced due to very low thermal conductivity, leading to internal differentiation. An internal thermal gradient causes widespread sublimation and migration of either ice condensates, or gases released from amorphous ice hosts during their crystallisation. Overall, the models predict that the degree of differentiation and re-distribution of volatile species to a shallower near-surface layer depends primarily on nucleus size. Hence, we hypothesise that cometary activity should reveal a correlation between the abundance of volatile species and the size of the nucleus. To explore this hypothesis we have conducted a thorough literature search for measurements of the composition and size of cometary nuclei, compiling these into a unified database. We report a statistically significant correlation between the measured abundance of CO/HO and the size of cometary nuclei. We further recover the measured slope of abundance as a function of size, using a theoretical model based on our previous thermophysical models, invoking re-entrapment of outward migrating high volatility gases in the near-surface pristine amorphous ice layers. This model replicates the observed trend and supports the theory of internal differentiation of cometary nuclei by early radiogenic heating. We make our database available for future studies, and we advocate for collection of more measurements to allow more precise and statistically significant analyses to be conducted in the future.
25 pages, 10 figures, published in MNRAS. Minor copyedit changes and updated links to data repositories
References in corpus (50)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- Array Programming with NumPy
- The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
- astroquery: An Astronomical Web-Querying Package in Python
- The Active Centaurs
- Elemental and molecular abundances in comet 67P/Churyumov-Gerasimenko
- Thermal Properties, Sizes, and Size Distribution of Jupiter-Family Cometary Nuclei
- Thirty Years of Cometary Spectroscopy from McDonald Observatory
- Outgassing of icy bodies in the solar system - I. The sublimation of hexagonal water ice through dust layers
- Terrestrial deuterium-to-hydrogen ratio in water in hyperactive comets
- The thermal, mechanical, structural, and dielectric properties of cometary nuclei after Rosetta
- Collisional Excavation of Asteroid (596) Scheila
- CO in distantly active comets
- Evolution of CO, CH, and OCS abundances relative to HO in the coma of comet 67P around perihelion from Rosetta/VIRTIS-H observations
- The Peculiar Volatile Composition of CO-Dominated Comet C/2016 R2 (PanSTARRS)
- Comets as collisional fragments of a primordial planetesimal disk
- Survey of cometary CO2, CO, and particulate emissions using the Spitzer Space Telescope: Smog check for comets
- A Survey of Water Production in 61 Comets from SOHO/SWAN Observations of Hydrogen Lyman-alpha: Twenty-One Years 1996-2016
- The Carbon Monoxide Abundance in Comet 103P/Hartley during the EPOXI Flyby
- The chemical composition of CO-rich comet C/2009 P1 (Garradd) at Rh = 2.4 and 2.0 AU before perihelion
- Thermophysical evolution of planetesimals in the Primordial Disk
- On the Origin and Thermal Stability of Arrokoths and Plutos Ices
- Uncorrelated Volatile Behavior During the 2011 Apparition of Comet C/2009 P1 Garradd
- High resolution optical spectroscopy of the -rich comet C/2016 R2 (PanSTARRS)
- A study of the distant activity of comet C/2006 W3 (Christensen) using Herschel and ground-based radio telescopes
- Strong CO and N Emission in Comet C/2016 R2 (Pan-STARRS)
- Evolution of HO, CO, and CO Production in Comet C/2009 P1 Garradd During the 2011-2012 Apparition
- Photometry and polarimetry of the nucleus of comet 2P/Encke
- Ground-based Optical and SPITZER Infrared Imaging Observations of Comet 21P/Giacobini-Zinner
- Ammonia and other parent molecules in comet 10P/Tempel 2 from Herschel/HIFI and ground-based radio observations
- Molecular composition of comet 46P/Wirtanen from millimetre-wave spectroscopy
- Monitoring of the activity and composition of comets 41P/Tuttle-Giacobini-Kresak and 45P/Honda-Mrkos-Pajdusakova
- Molecular investigations of comets C/2002 X5 (Kudo-Fujikawa), C/2002 V1 (NEAT), and C/2006 P1 (McNaught) at small heliocentric distances
- Long-term activity and outburst of comet C/2013 A1 (Siding Spring) from narrow-band photometry and long-slit spectroscopy
- FUV Spectral Signatures of Molecules and the Evolution of the Gaseous Coma of Comet 67P/Churyumov-Gerasimenko
- Are there any pristine comets? Constraints from pebble structure
- Sublimation of ices during the early evolution of Kuiper belt objects
- Spectroscopic Observations of the Comet 29P/Schwassmann-Wachmann 1 at the SOAR Telescope
- Water, hydrogen cyanide, carbon monoxide, and dust production from distant comet 29P/Schwassmann-Wachmann 1
- Properties of the Bare Nucleus of Comet 96P/Machholz 1
- Earth-based detection of the millimetric thermal emission of the nucleus of comet 8P/Tuttle
- Hubble Space Telescope Search for Activity in High Perihelion Objects
- Simulation and experiment of gas diffusion in a granular bed
- Water Production Rate of C/2020 F3 (NEOWISE) from SOHO/SWAN over Its Active Apparition
- A method to distinguish between micro- and macro-granular surfaces of small Solar System bodies
- Low NH/HO ratio in comet C/2020 F3 (NEOWISE) at 0.7 au from the Sun
- Millimetre continuum observations of comet C/2009 P1 (Garradd)
- Behavioral Characteristics and CO+CO2 Production Rates of Halley-Type Comets Observed by NEOWISE
- Chemistry of comet atmospheres
- Radiative processes as diagnostics of cometary atmospheres