chondrules Archives

Planetary system formation -- Astrobiology.com and NASA.gov

Our Solar System Chose Fire Over Ice To Build Its First Bodies

by Keith CowingOctober 1, 2026October 1, 2026

[Yale University] When the solar system first took up the task of building solid bodies — such as planets, moons, and protoplanets — it basically had a choice between two […]

An SwRI-led study modeled the concentration

Astrogeology

SwRI Study Found Primordial Mini-moons May Explain Meteorite Composition

by Keith CowingJuly 10, 2026July 23, 2026

[SwRI] A new Southwest Research Institute-led study proposes a solution to a long-standing puzzle in planetary science — what caused the concentration, assembly and preservation of millimeter-sized, spherical mineral grains […]

The element abundances in the silicate Earth can be modelled as the result of accretion of three distinct components with distinct element abundances and isotope composition: A: a strongly volatile element depleted and reduced proto-Earth, B: a moderately volatile depleted and more oxidized Moon-forming impactor (Theia) and C: a near chondritic and oxidized late veneer. The absolute abundance of the siderophile and chalcophile elements was modified by core formation following accretion (after Mezger et al., 2021). -- astro-ph.EP

Astrochemistry, Astrogeology, Comets and Asteroids, Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Lava / magma ocean / Volcanic Worlds, Meteorites & Asteroids, Status Report, Water/Hycean Worlds & Oceanography

From Dust to Planets — A Chemical Perspective

by Keith CowingApril 20, 2026April 20, 2026

Chemical and chronological information preserved in meteorites permits the reconstruction of events and processes in the solar nebula from the formation of the first solids to the accretion of planetary […]

Artist impression of solar system formation. Presolar grains are tiny, solid grains of primitive solar system material that originated before the formation of the Sun. They have been found in many places, including interplanetary dust, meteorites, and even samples from the comet Wild-2 that were returned to Earth by NASA's Stardust mission. Image credit: Gemini Observatory/AURA/Lynette Cook via NASA Astrobiology

Astrochemistry, Astrogeology, Biogeochemical Cycles & Geobiology, Meteorites & Asteroids, Status Report

Origin Of Moderately Volatile Elements In Earth

by Keith CowingMay 13, 2025May 13, 2025

The bulk silicate Earth (BSE) is depleted in moderately volatile elements, indicating Earth formed from a mixture of volatile-rich and -poor materials.

1D spherical vapor plume expansion and flow reversal. Example vapor plume evolution starting with an 80 GPa water sphere of radius 25 km, expanding into a dust-free nebular gas at 10−6 bars. In panels A-D, the thick dashed line represents the material boundary between the inner water vapor plume and outer nebular gas. The color shading presents radial velocity (A), pressure (B), density (C), and temperature (D) versus time. The streamlines (thin grey in A; thin white in B-D) indicate the flow history of the gas and any fully coupled dust. The nebular shock generated by the expanding vapor plume creates a transiently hot nebular environment that expands and cools on the time scale of hours. The inset (E) is a close-in view of the initial hot nebular shock front. In panel C, points A-E are used to illustrate size sorting in the outward flow in section 6. We propose chondrules form and cool in the transiently shocked (dusty) nebular gas. The supplemental materials contain an interactive version of this figure. -- astro-ph.EP

Astrochemistry, Astrogeology, Biogeochemical Cycles & Geobiology, Impact events, Meteorites & Asteroids, Status Report

Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures

by Keith CowingMarch 14, 2025March 14, 2025

The origin of chondrules, and the chondritic sedimentary rocks that dominate the meteoritic record, is a long-standing problem in planetary science. Here, we develop a physical model for the formation […]

A schematic chronology of the early asteroid belt based on the evidence discussed in the text. CAI formation defines t = 0 and primary planetesimals are assumed to form quickly. Within a few hundred thousand years most of the mass is in the form of large planetesimals, which become dominated by magma interiors, as shown by the red line labeled magma fraction. The energy source is 26Al, whose level declines with a half-life of 0.717 Ma from an assumed initial value of 4 at t = 0, where a level of 1 corresponds to the amount of energy (1.6 kJ/g) needed to just reach the liquidus of a perfectly insulated cold primitive starting material. Chondrules formed between ∼1-4 Ma when exposed to hot magma released during a collision, as illustrated by the drawing in the right hand panel by David A. Harvey (astroart.com) originally depicting the formation of a ring around the Earth. Chondrule formation ends when the LDPs have cooled sufficiently that magma does not reach their surfaces even during collisions. Jupiter may form at around 3-4 Ma and begin clearing the asteroid belt of many of its larger objects. -- astro-ph.EP

Astrochemistry, Astrogeology, Comets and Asteroids, Meteorites & Asteroids, Status Report

Chondrule Formation During Low-Speed Collisions of Planetesimals: A Hybrid Splash-Flyby Framework

by Keith CowingFebruary 21, 2024February 21, 2024

Chondrules probably formed during a small window of time ∼1-4 Ma after CAIs, when most solid matter in the asteroid belt was already in the form of km-sized planetesimals.

Chondrules and matrix in the Mokoia CV-chondrite with backscattered electrons. The darker chondrules indicate lower FeO contents. Bright spots are sulfides or metal. -- physics.geo-ph

Astrochemistry, Astrogeology, Comets and Asteroids, Meteorites & Asteroids, Status Report

The Origin Of Chondrules: Constraints From Matrix-Chondrule Complementarity

by Keith CowingJuly 6, 2023July 6, 2023

One of the major unresolved problems in cosmochemistry is the origin of chondrules, once molten, spherical silicate droplets with diameters of 0.2 to 2 mm.

Mg-Ca-Al = red-green-blue x-ray mosaics of (A) Kainsaz 4717-1Cp1 (CO 3.2), showing clast outlines (yellow lines) in right hand portion; (B) Allende AL2ps25 (CVOxA ~3.6), showing outlines and clasts labels; (C) Vigarano (CV-R 3.3), showing outlines; (D) ~800 µm chondrule in Colony (CO 3.0), plane polarized light image (upper) and x-ray mosaic (lower) showing outline (dashed line); (E) Tibooburra (CV 3), showing outlines and, on right, grayscale input to ImageJ step of analysis algorithm; and (F) cropped area of Acfer 094 (C2-ungr) showing outlines (yellow). -- astro-ph.EP

Astrochemistry, Astrogeology, Comets and Asteroids, Meteorites & Asteroids, Status Report

Abundance, Major Element Composition and Size of Components and Matrix in CV, CO and Acfer 094 Chondrites

by Keith CowingJune 27, 2023June 27, 2023

The relative abundances and chemical compositions of the macroscopic components or “inclusions” (chondrules and refractory inclusions) and fine-grained mineral matrix in chondritic meteorites provide constraints on astrophysical theories of inclusion […]

Timescale for isotope exchange reaction, τ, as a function of Pwater and vrel (solid lines). The vertical dashed line represents vrel at s16 = 0.2 (see Section 3.1.2). Here, we set T = 2000 K, r = 0.5 mm, χ = 1, and β16 = 0.3. The dashed lines represent the timescale of homogenization, τhomo, as a function of PH2 and vrel (see Section 4.2). -- astro-ph.EP

Astrochemistry, Astrogeology, Biogeochemical Cycles & Geobiology, Status Report

Oxygen Isotope Exchange Between Molten Silicate Spherules and Ambient Water Vapor with Nonzero Relative Velocity: Implication for Chondrule Formation Environment

by Keith CowingJune 26, 2023June 26, 2023

Oxygen isotope compositions of chondrules reflect the environment of chondrule formation and its spatial and temporal variations.

Cartoon illustrating our preferred scenario

Astrochemistry, Astrogeology, Comets and Asteroids, Meteorites & Asteroids, Status Report

Origin Of Isotopic Diversity Among Carbonaceous Chondrites

by Keith CowingMarch 8, 2023March 8, 2023

Carbonaceous chondrites are some of the most primitive meteorites and derive from planetesimals that formed a few million years after the beginning of the solar system.