Dust coagulation and fragmentation in molecular clouds. I. How collisions between dust aggregates alter the dust size distribution

By C. Ormel, D. Paszun, C. Dominik, A. Tielens. 2009

184 citations recorded by the source corpus.

The cores in molecular clouds are the densest and coldest regions of the interstellar medium (ISM). In these regions ISM-dust grains have the potential to coagulate. This study investigates the collisional evolution of the dust population by combining two models: a binary model that simulates the collision between two aggregates and a coagulation model that computes the dust size distribution with time. In the first, results from a parameter study quantify the outcome of the collision – sticking, fragmentation (shattering, breakage, and erosion) – and the effects on the internal structure of the particles in tabular format. These tables are then used as input for the dust evolution model, which is applied to an homogeneous and static cloud of temperature 10 K and gas densities between 10 3 and 10 7 cm −3 . The coagulation is followed locally on timescales of ∼10 7 yr. We find that the growth can be divided into two stages: a growth dominated phase and a fragmentation dominated phase. Initially, the mass distribution is relatively narrow and shifts to larger sizes with time. At a certain point, dependent on the material properties of the grains as well as on the gas density, collision velocities will become sufficiently energetic to fragment particles, halting the growth and replenishing particles of lower mass. Eventually, a steady state is reached, where the mass distribution is characterized by a mass spectrum of approximately equal amount of mass per logarithmic size bin. The amount of growth that is achieved depends on the cloud’s lifetime. If clouds exist on free-fall timescales the effects of coagulation on the dust size distribution are very minor. On the other hand, if clouds have long-term support mechanisms, the impact of coagulation is important, resulting in a significant decrease of the opacity on timescales longer than the initial collision timescale between big grains.

Subfields: Astronomy and Astrophysics, Atmospheric Science, Fluid Flow and Transfer Processes

View Paper: https://www.semanticscholar.org/paper/23b4f6f46e5a524aac90716caf979cc4d277f53d

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. T. Birnstiel
2. Anders Johansen
3. C. Dullemond
4. C. Ormel
5. L. Ricci
6. L. Testi
7. M. Fang
8. S. Andrews

In Atmospheric Science

1. D. Whittet
2. F. Brauer
3. C. Dullemond
4. T. Birnstiel
5. A. Boogert

In Fluid Flow and Transfer Processes

1. T. Birnstiel
2. C. Ormel
3. C. Dullemond
4. L. Ricci
5. J. Blum
6. Anders Johansen
7. Simon Bruderer
8. A. Youdin

Citations in the corpus

• Dust size distributions in coagulation/fragmentation equilibrium: numerical solutions and analytical fits (2010, result): “This distinction between an erosion and a shattering regime follows the numerical studies of Paszun & Dominik (2009) and Ormel et al. (2009) and experimental studies of Güttler et al. (2010).”
• Observations of the Icy Universe (2015, background): “Coagulation of the sticky icy grains will lead to further growth in dense molecular clouds (Ormel et al., 2009).”
• Dust Evolution and the Formation of Planetesimals (2016, background): “(26) Similar calculations can be done for other relative velocities and they produce trends of numerical simulations well (e.g., Ormel et al. 2009; Birnstiel et al. 2010; Windmark et al. 2012a).”
• Dust grain growth in ρ-Ophiuchi protoplanetary disks (2010, background): “Since evidence for grain growth to millimeter sizes appears to be present in some class 0 YSOs the formation of the ∼mm-sized grains seen in class II disks may already occur in the densest inner regions of molecular cloud cores (Ormel et al. 2009).”
• Gas- and dust evolution in protoplanetary disks (2010, background): “Typical values have been found in the range between 1 and 2, by both experimental (e.g.,Blum & Muench 1993; Davis & Ryan 1990) and theoretical studies (Ormel et al. 2009).”
• THE STICKINESS OF MICROMETER-SIZED WATER-ICE PARTICLES (2014, background): “Dust coagulation plays an important role in the densest interstellar regions, i.e., in molecular clouds (Ossenkopf 1993; Weidenschilling & Ruzmaikina 1994; Ormel et al. 2009) and protoplanetary disks (Blum & Wurm 2008; Zsom et al. 2010; Testi et al. 2014).”