CRYSTALLINE SILICATES AND DUST PROCESSING IN THE PROTOPLANETARY DISKS OF THE TAURUS YOUNG CLUSTER

By D. Watson, J. Leisenring, E. Furlan, C. Bohac, B. Sargent, W. Forrest, N. Calvet, L. Hartmann, J. Nordhaus, Joel D. Green and 8 more. 2007

139 citations recorded by the source corpus.

We characterize the crystalline-silicate content and spatial distribution of small dust grains in a large sample of protoplanetary disks in the Taurus-Auriga young cluster, using the Spitzer Space Telescope mid-IR spectra. In turn we use the results to analyze the evolution of structure and composition of these 1–2 Myr old disks around Solar- and later-type young stars, and test the standard models of dust processing which result in the conversion of originally amorphous dust into minerals. We find strong evidence of evolution of the dust-crystalline mass fraction in parallel with that of the structure of the disks, in the sense that increasing crystalline mass fraction is strongly linked to dust settling to the disk midplane. We also confirm that the crystalline silicates are confined to small radii, r ≲ 10 AU. However, we see no significant correlation of crystalline mass fraction with stellar mass or luminosity, stellar-accretion rate, disk mass, or disk/star mass ratio, as would be expected in the standard models of dust processing based upon photoevaporation and condensation close to the central star, accretion-heating-driven annealing at r ≲ 1 AU, or spiral-shock heating at r ≲ 10 AU, with or without effective large-scale radial mixing mechanisms. Either another grain-crystallizing mechanism dominates over these, or another process must be at work within the disks to erase the correlations they produce. We propose one of each sort that seems to be worth further investigation, namely X-ray heating and annealing of dust grains, and modulation of disk structure by giant-planetary formation and migration.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/69a33c05f3da465196868512ab7aa2293d99eb7b

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In Astronomy and Astrophysics

1. Xue-Ning Bai
2. E. Bergin
3. K. Oberg
4. Maarten Baes
5. J. Steinacker
6. K. Gordon
7. N. Madhusudhan
8. R. Garrod

In Spectroscopy

1. E. Bergin
2. K. Oberg
3. Xue-Ning Bai
4. R. Garrod
5. E. Dishoeck
6. P. Caselli
7. Cecilia Ceccarelli
8. E. Herbst

Citations in the corpus

• Astrochemistry and compositions of planetary systems (2020, result): “This conclusion is supported by observations revealing thermal processing of small silicate particles in disks (Waelkens et al. 1996; Malfait et al. 1998; van Boekel et al. 2004; Watson et al. 2009).”
• Three-Dimensional Dust Radiative Transfer ∗ (2013, background): “49 98 v2 [ substellar atmospheres (Harvey et al. 2012), young stellar objects (Keller et al. 2008), protostellar to protoplanetary disks (Watson et al. 2009), evolved stars (Groenewegen et al. 2011), reflection nebulae (Castellanos et al. 2011), supernova remnants (Rho et al. 2009), molecular…”
• Global Simulations of the Inner Regions of Protoplanetary Disks with Comprehensive Disk Microphysics (2017, result): “Similar evidence has been found in nearby PPDs (van Boekel et al. 2004; Watson et al. 2009).”