Kavli Affiliate: Gregory J. Herczeg
| First 5 Authors: Marbely Micolta, Nuria Calvet, Thanawuth Thanathibodee, Gladis Magris C., Carlo F. Manara
| Summary:
We present a study of the abundance of calcium in the innermost disk of 70 T
Tauri stars in the star-forming regions of Chamaeleon I, Lupus and Orion OB1b.
We use calcium as a proxy for the refractory material that reaches the inner
disk. We used magnetospheric accretion models to analyze the Ca II emission
lines and estimate abundances in the accretion flows of the stars, which feed
from the inner disks. We find Ca depletion in disks of all three star-forming
regions, with 57% of the sample having [Ca/H] < -0.30 relative to the solar
abundance. All disks with cavities and/or substructures show depletion,
consistent with trapping of refractories in pressure bumps. Significant Ca
depletion ([Ca/H] < -0.30) is also measured in 60% of full disks, although some
of those disks may have hidden substructures or cavities. We find no
correlation between Ca abundance and stellar or disk parameters except for the
mass accretion rate onto the star. This could suggest that the inner and outer
disks are decoupled, and that the mass accretion rate is related to a mass
reservoir in the inner disk, while refractory depletion reflects phenomena in
the outer disk related to the presence of structure and forming planets. Our
results of refractory depletion and timescales for depletion are qualitatively
consistent with expectations of dust growth and radial drift including
partitioning of elements and constitute direct evidence that radial drift of
solids locked in pebbles takes place in disks.
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