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HYDROCARBON EMISSION RINGS IN PROTOPLANETARY DISKS INDUCED BY DUST EVOLUTION

Bergin, Edwin A. ; Du, Fujun ; Cleeves, L. Ilsedore ; Blake, G. A. ; Schwarz, K. ; Visser, R. ; Zhang, K.

The Astrophysical journal, 2016-11, Vol.831 (1), p.101 [Periódico revisado por pares]

Philadelphia: The American Astronomical Society

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Título:
HYDROCARBON EMISSION RINGS IN PROTOPLANETARY DISKS INDUCED BY DUST EVOLUTION
Autor: Bergin, Edwin A. ; Du, Fujun ; Cleeves, L. Ilsedore ; Blake, G. A. ; Schwarz, K. ; Visser, R. ; Zhang, K.
Assuntos: ABUNDANCE ; astrochemistry ; Astrophysics ; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY ; Atmospheric chemistry ; CARBON MONOXIDE ; circumstellar matter ; Coagulation ; CONCENTRATION RATIO ; Continuum radiation ; COSMIC DUST ; Disks ; Dust ; EMISSION ; Grains ; Gravitational effects ; HYDROCARBONS ; ICE ; INTERACTIONS ; LAYERS ; MASS ; molecular processes ; Organic chemistry ; OXYGEN ; Photochemicals ; PHOTOCHEMISTRY ; PHOTONS ; Planet formation ; planet-disk interactions ; planetary systems ; PLANETS ; planets and satellites: atmospheres ; Protoplanetary disks ; PROTOPLANETS ; Radio telescopes ; SATELLITE ATMOSPHERES ; SATELLITES ; SPATIAL DISTRIBUTION ; STRATIFICATION ; Submillimeter waves ; Surface boundary layer ; Surface layers ; SURFACES
É parte de: The Astrophysical journal, 2016-11, Vol.831 (1), p.101
Notas: AAS00883
The Solar System, Exoplanets, and Astrobiology
Descrição: ABSTRACT We report observations of resolved C2H emission rings within the gas-rich protoplanetary disks of TW Hya and DM Tau using the Atacama Large Millimeter Array. In each case the emission ring is found to arise at the edge of the observable disk of millimeter-sized grains (pebbles) traced by submillimeter-wave continuum emission. In addition, we detect a C3H2 emission ring with an identical spatial distribution to C2H in the TW Hya disk. This suggests that these are hydrocarbon rings (i.e., not limited to C2H). Using a detailed thermo-chemical model we show that reproducing the emission from C2H requires a strong UV field and C/O > 1 in the upper disk atmosphere and outer disk, beyond the edge of the pebble disk. This naturally arises in a disk where the ice-coated dust mass is spatially stratified due to the combined effects of coagulation, gravitational settling and drift. This stratification causes the disk surface and outer disk to have a greater permeability to UV photons. Furthermore the concentration of ices that transport key volatile carriers of oxygen and carbon in the midplane, along with photochemical erosion of CO, leads to an elemental C/O ratio that exceeds unity in the UV-dominated disk. Thus the motions of the grains, and not the gas, lead to a rich hydrocarbon chemistry in disk surface layers and in the outer disk midplane.
Editor: Philadelphia: The American Astronomical Society
Idioma: Inglês

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HYDROCARBON EMISSION RINGS IN PROTOPLANETARY DISKS INDUCED BY DUST EVOLUTION

Bergin, Edwin A. ; Du, Fujun ; Cleeves, L. Ilsedore ; Blake, G. A. ; Schwarz, K. ; Visser, R. ; Zhang, K.

Philadelphia: The American Astronomical Society

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