adsabs/AstroCLIMB huggingface dataset:
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Many planetesimal collisions are disruptive and vaporizing. (A) Histogram of mutual planetesimal collision velocities (corrected for particle size inflation) from a Grand Tack N-body simulation (022GTJf6hgas) in P. J. Carter & S. T. Stewart (2022). In this example, 57% of the collisions are faster than 1 km s−1 (see Figure 20 in Appendix C). (B) Escape velocities (vesc; dotted black line) and catastrophic disruption velocities (v*; red dotted–dashed line) compared to the critical velocities for shock-induced vaporization: incipient vaporization (viv) for H2O ice at an initial temperature T0 = 150 K (about 1 km s−1; solid blue line) and forsterite (Mg2SiO4) at T0 = 300 K (about 10 km s−1; gray line) and 50% vaporization (v50%) for H2O ice (about 6.5 km s−1; blue dashed line). Giant planet migration leads to erosive or disruptive collisions between hundreds of kilometer-sized planetesimals. Many events also partially vaporize water ice, but impact vaporization of silicates is much less common.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Protoplanets can dynamically excite a population of nearby planetesimals into the vaporization regime. Critical eccentricities (colored lines) define the threshold where the mean relative velocity between planetesimals is equal to a critical velocity for shock-induced vaporization (Equation (A3)): incipient vaporization for T0 = 150 K ice (1 km s−1; blue), incipient vaporization for T0 = 300 K forsterite (10 km s−1; green), and an intermediate velocity (5 km s−1; orange). Black lines denote the mean eccentricities for a population of 100 km radius planetesimals that are dynamically stirred by a single planet of varying mass (line styles) in the oligarchic growth regime with a nebular gas density of ρneb = 10−7 kg m−3 (Equation (A4)). Gray lines have ρneb = 10−6 kg m−3. The magnitude of dynamical stirring is greater for larger-mass planets, planets closer to the Sun, and decreasing nebular gas density.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: 3D vapor plume expansion and collapse. An example 3D vapor plume evolution starting with ice–silica bodies colliding at 6 km s−1. The surrounding nebular gas is dust-free at 10−6 bars and 200 K. (A) The principal direction of the vapor plume expands more rapidly than the solid fragments from the disrupted bodies. In the schematic, the region within the blue cone contains water vapor and condensed silica. The region between the blue and black cones contains shocked nebular (H–He) gas. Beyond the black cone is the undisturbed ambient nebular gas. (B) The cool solid fragments from the disrupted bodies have slower velocities compared to the fast impact vapor in the principal direction of the plume. (C) The inward turbulent flow in the principal direction mixed shocked nebula and plume debris far downrange from the largest fragments from the disrupted bodies. (D) The material collected at the leading face of the plume is sorted by the reverse sieve effect described in Section 6. The schematic light blue zone is a mixture of plume materials and nebular materials. Note the change in scale at each time step. Animations of this impact are available at https://chondrules.net/ivans/.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: 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) vs. time. The streamlines (thin gray 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 a timescale 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 that chondrules form and cool in the transiently shocked (dusty) nebular gas. An interactive version of this figure can be found at https://chondrules.net/ivans/.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Schematic overview of the hydrodynamics of impact vapor plumes and nebular shocks. (A) Planetesimals comprised of refractory dust and ice collide in a disruptive and vaporizing event surrounded by dusty nebular gas. (B) The impact generates an expanding cloud of cooling water vapor and debris from the planetesimal. The vapor plume expands supersonically (inner blue region), driving a warmer shock wave into the solar nebula (outer ring with warm colors). The elongated expanding shell of shocked nebula is hotter in the principal impact direction and cooler in the opposite and lateral dimensions (indicated by the color gradient). Portions of the shocked nebula are warm enough to melt free-floating nebular dust and form chondrules; other regions experience less thermal processing. (C) The nebular shock decays to a sound wave as it expands. Expansion of the vapor plume leads to a pressure low in the solar nebula and subsequent hydrodynamic reversal in the flow field. The nebular gas, dust, and chondrules flow into the low-pressure region, mixing materials that were processed in different regions. The collapsed mixture has the characteristics observed in chondritic mixtures: quenched chondrules mixed with dust and ice. The mixed region is orders of magnitude larger in scale than the original planetesimals (e.g., megameter-scale mixed regions). The timescale of the collapse is of order tens of hours.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: 2D vapor plume expansion and collapse. Example 2D cylindrically symmetric vapor plume evolution starting with ice–silica bodies colliding at 6 km s−1. The surrounding nebular gas is dust-free at 0.1 Pa and 200 K. (A) Initially, the vapor plume is denser than the surrounding shocked nebula, indicated by the shell of hot gas bounded by the exterior nebular shock and the nebula–plume interface. The water vapor plume is cool with small amounts of hot silica gas. The principal direction of the vapor plume generates a much hotter nebular shock than the opposite direction. In the schematic, the region within the blue line contains water vapor and condensed silica. The ring between the blue and black lines contains shocked nebular (H–He) gas. Beyond the black line is the undisturbed ambient nebular gas. (B) As the pressure and density drops in the vapor plume, turbulent eddies form at the nebula–plume interface. (C) The inward turbulent flow mixes plume and nebular materials in a warm cloud about 104 times greater in size than the original planetesimals. The schematic light blue zone is a mixture of plume materials and nebular materials. Note the change in scale at each time step. Animations of this impact are available at https://chondrules.net/ivans/.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Schematic of the different dimensionalities for impact vapor plume calculations. The simulated regions are indicated in blue. (A) Full 3D hydrocode calculations of colliding spherical bodies. The direction of the larger velocity vector in the nebular frame of reference is the principal direction of the vapor plume. (B) 2D cylindrically symmetric calculation with the symmetry axis denoted by the dashed line. The full target is on the center line, and the projectile is represented by a torus with mass equal to the interacting portion of the projectile. (C) The regions shocked to the highest-pressure states in the 3D event (shaded blue zones) are approximated by a 1D sphere initialized in a shocked state on the principal Hugoniot. In all cases, the initial bodies are surrounded by ambient nebular gas.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Ideal dust–gas mixture Hugoniots. The relative compressibility of a dusty gas is much greater than for a pure ideal gas. (A) Shock Hugoniots for an ideal dusty gas with varying dust-to-gas mass ratios (md/mg), with density normalized to the initial density. Each Hugoniot originates at 200 K and 0.137 Pa (see Table 2). Note that the md/mg = 0.01 and 0.1 curves are indistinguishable on these scales. (B) At a fixed shock temperature, the corresponding shock pressure is greater as the dust-to-gas mass fraction increases. A wide range of pressure–temperature conditions is possible in a shocked dusty gas, as discussed below. Bars show the stability range for liquids in various dust-enriched nebular compositions from this study (gray; see Section 5.2 and Table 3) and D. S. Ebel & L. Grossman (2000; blue).
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Plume stall radius scaling law. A power law (black line) relates the mass displaced by the plume expansion to the impact energy for a wide range of impact conditions. Results for water vapor plumes expanding into dusty gas (filled symbols indicating the dust-to-gas ratio). The dusty-gas pressure was 0.1 Pa, and the initial pressure of the plume is indicated by the color of the symbols. Other symbols show the results for expansion of water (light blue) or silica (gray) into dust-free gas. The lowest-energy events do not generate strong shock waves or substantial amounts of vapor and fall off the general power law. See Tables 1 and 5 for full details of the simulation parameters.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Plume stall time scaling law. The power law (black line) relates the plume stall time and radius for a wide range of impact conditions. The dusty-gas pressure was 0.1 Pa. Color legend for initial pressure in water–dusty gas cases only; see Tables 1 and 5.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: 1D water vapor plume expansion results. Results from dust-free nebula simulations demonstrating the systematic dependence for the plume stall radius and time on the initial radius of the plume source, initial shock pressure (colors), and the pressure (or density) of the nebular gas (symbols).
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Schematic of particles coupled in the nebular shock front during expansion and collapse of a spherical vapor plume. The nebular shock front expands in size and decays in strength as it propagates into the nebula. Panels (A)–(E) are not-to-scale representations of particle thermal processing and size sorting at different times during plume evolution shown on the left (example shown in Figure 5). Gas flow streamlines are shown with thin gray lines labeled a, b, and c, which illustrate the compression from the plume expansion and nebular shock. Panels (A)–(E) background colors represent the water vapor transient environment (blues) and the shocked nebula transient environment (orange). The plume region heated by the inward-propagating shock is dark blue ((D) and (E)). The shock front acts like a reverse filter, collecting smaller particles and flowing past larger particles. The nebula–plume interface becomes unstable to turbulent mixing as the density in the plume decreases (D). Size-sorted particles with different thermal histories are collected and mixed near the nebula–plume interface during plume collapse (dashed line region in (E)). Note that the 1D code does not capture the turbulence at the nebula–plume interface or the plume collapse from the lateral directions, as shown in Figures 3 and 7.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Shock impedance match solution for the water plume and different nebular dust–gas mixtures. (A) Spherical decompression paths (blue curves) for a 25 km radius water-ice sphere initially shocked to pressures (P0) of 10, 20, and 40 GPa in the rest frame of the nebula (up,0 = 0), calculated using the 1D pyKO code. The pressure and particle velocity of the initial shock in the ambient nebula are defined by the intersection between the water decompression path and the shock Hugoniot (color gradient lines) of the nebular gas. Here, the nebula initial state is 0.1 Pa and 200 K, and the lines with temperature color gradients correspond to varying dust-to-gas mass ratios (md/mg) as labeled. Increasing the dust mass fraction in the nebular gas leads to greater initial pressures in the nebular shock (e.g., point a vs. b). In addition, adding dust lowers the shock pressure required to reach silicate-melting temperatures. The kinks in the H2O decompression paths correspond to the intersection with the water vapor curve. (B) Varying initial pressure in the nebula shifts the nebular shock Hugoniot up or down. (C) Varying the relative velocity of the plume to the nebula shifts the plume decompression path left or right.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Impact velocity probabilities and compositional dependence on shock pressure. (A) Example cumulative probability distribution for mutual planetesimal collision velocities (corrected for particle size inflation) from a Grand Tack N-body simulation (022GTJf6hgas) in P. J. Carter & S. T. Stewart (2020). This is the same distribution as shown in Figure 1. (B) Shock Hugoniots for pure forsterite (Fo; green; experimental) and pure H2O ice (blue; experimental) and Fo–ice mixtures (dashed; calculated) in terms of the impact velocity between the same composition bodies. The impact velocity required to reach 40 GPa (gray dotted line) depends on the composition. The probabilities corresponding to 40 GPa events are indicated by vertical lines in panel (A). In about half the impacts, (i) the planetesimal is disrupted, (ii) the silicate fraction is not melted (P < 189 GPa; E. J. Davies et al. 2020), and (iii) the ice fraction is partially vaporized (P > 3.5 GPa; S. Stewart et al. 2008; R. G. Kraus et al. 2011).
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Impact parameter distributions. In most collisions, one of the impactors is on a low-excitation orbit, while the other is excited. Shown are the velocities of the target with respect to the nebular gas and of the projectile with respect to the target for collisions in the simulation from Figure 1 (run 022GTJf6hgas from P. J. Carter & S. T. Stewart 2022). The left two panels show histograms for the target and projectile velocities, while the right four panels show 2D histograms for the velocities of the target and projectile, where the color scale indicates the number of impacts in each bin. The azimuthal, radial, and vertical velocity components are shown, as well as the overall magnitude. Collision velocity components mostly fall into two distinct bands: the horizontal band indicates that the target is moving on approximately a circular orbit, similar to the nebular gas while the projectile is on an excited orbit; the band with a slope of approximately −1 indicates collisions in which the target is excited while the projectile has almost the opposite motion, corresponding to an orbit similar to the gas. Outside of these bands, both target and projectile are on excited orbits, with the distributions being determined by the dynamics of the giant planets. In the magnitude panel, these bands become horizontal and +1 sloped.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Pressure–temperature histories in expanding nebular shocks. Example pressure–temperature paths for the shocked nebula with different dust-to-gas ratios. Each row presents the history for material originating at the nebula–plume interface (rp; solid lines), halfway to the stall radius (rs/2; dashed lines), and at the stall radius (rs; dotted lines) for four events (25 km radius water plume) with dust-to-gas mass ratios of 1 and 100. The vertical gray line indicates the stall time of the nebula–plume interface. The initial nebula was at 200 K and 0.137 Pa.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Particle–gas coupling in the expanding plume and nebular shock. The maximum size of the particles is coupled to the outward flow in a Monte Carlo suite of simulations that explored a wide range of plume and nebular properties. The upper right edges of the point cloud reflect the end ranges of the parameters considered in the Monte Carlo model. The size of the coupled particles (droplets or aggregates) depends primarily on the density of preshock gas for a dust-free H2–He mixture. The size of the aggregates is given as the equivalent size of the aggregate after it has been melted to form a chondrule.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Temperature histories and cooling rates in expanding nebular shocks. (Left column) Temperature as a function of time for different parts of the nebular shock as shown in the first column of Figure 14. Each row is for a different initial plume pressure and nebular gas-to-dust ratio. The vertical gray line indicates the stall time of the nebula–plume interface. (Right column) Cooling rates for shocked nebular dust–gas mixtures at different times for parcels of nebular material at the nebula–plume interface (circles), halfway to the stall radius (three-pointed triangles), and at the stall radius (line segments), excluding the highest-temperature examples, as the model equation of state does not include melting or vaporization.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Nebular temperature and pressure distributions within the stall radius. Cumulative volume (or, equivalently, mass) fractions are below each temperature and pressure within the plume stall radius. Results for nebular shock states are driven by spherical 25 km radius water vapor plume expansion from initial pressures of 15, 20, 40, and 80 GPa. The initial nebular states were 200 K and 0.137 Pa with dust-to-gas mass ratios of 1 and 100.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Self-gravitating cloud collapse criteria. (A) With the high solid-to-gas mass ratio implied by chondrule compositions (hundreds to ten thousands), the plumes generated by vaporizing collisions must be hundreds to tens of megameters in size to quickly form a new planetesimal. (B) In such cases, the collapse time would be of order tens to hundreds of days.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Plume radius with time. The 1D plume expansion front (dashed line from Figure 5) does not follow a self-similar solution where R ∝ t2/5 (solid gray line; L. I. Sedov 2018). Initially, the expansion is more linear (dotted line) and then has an expansion stage with a t2/5 curvature (black line is time-shifted gray line) for about a quarter of the time before the stall point (circle). A similar offset in plume front curvature is seen in laboratory experiments of vapor expanding into a background gas (J. J. Pilgram et al. 2024).
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Mean free path in ideal dust–gas mixtures. For a wide range of expected dust-to-gas mass ratios (md/mg; see Table 3) and dust sizes, the mean free path is much smaller than the scale of the nebular shocks generated by the expanding impact vapor plume (hundreds of megameters). Thus, the shocked nebular gas and the surrounding ambient nebular gas will be optically thick.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: Properties of an ideal dust–gas mixture equation of state. Mixture physical properties (A)–(E) and shock Hugoniots (F) for different initial dust-to-gas mass ratios for an initial state at 200 K and 0.137 Pa. For md/mg ≤ 0.1, the shock Hugoniots are similar to a pure gas.
Paper: Planetesimal Impact Vapor Plumes and Nebular Shocks Form Chondritic Mixtures
Authors: Sarah T. Stewart, Simon J. Lock, Philip J. Carter, Erik J. Davies, Michail I. Petaev, Stein B. Jacobsen
Figure caption: The nebular shock and expanding vapor plume are likely to be optically thick. (A) The mean free path of photons in a mixture of micron-sized dust and millimeter-sized spherules as a function of the total mass density of condensates and the fraction of the mass that is dust (Equation (H5)). (B) The corresponding number density of particles for each total mass density of condensates and dust mass fraction.