Observations of Water and other molecules in Protoplanetary Disk Atmospheres Colette Salyk UT...
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Transcript of Observations of Water and other molecules in Protoplanetary Disk Atmospheres Colette Salyk UT...
Observations of Water and other molecules in Protoplanetary Disk
Atmospheres
Colette SalykUT Austin/McDonald ObservatoryKlaus Pontoppidan, Geoffrey Blake, Rowin Meijerink,
Joan Najita, John Carr
Water vapor and organics detected in ‘typical’ circumstellar disks with Spitzer-IRS
Spitzer IRS: Carr & Najita 2008; Salyk et al. 2008 T~500-1000 K
Ground-based follow-up confirms origin in planet-forming region of disk
Salyk et al. 2008
Line profiles consistent with ~few AU emitting radii
What disk processes might water emission probe?
Radial transport of water via diffusion (out) and icy-body migration (in)
“snow line”
e.g. Stevenson & Lunine 1988; Ciesla & Cuzzi 2006
vapor freezes out
vapor diffuses outwards
low vapor pressurehigh vapor pressure
solids migrate inwardssolids evaporate
What disk processes might water emission probe?
Radial transport of water via diffusion (out) and icy-body migration (in)
Water self-shielding
Bethell & Bergin 2009
What disk processes might water emission probe?
Radial transport of water via diffusion (out) and icy-body migration (in)
Water self-shielding
Radiative processes
Condensation fronts and vertical transport
Disk chemistry
Small dust grain growth/settling
Clearly a challenge to disentangle multiple effects
GO5 program: Water in Disks (PI: J. Carr)
-52 class II disks in multiple star-forming regions-Designed to cover a range of stellar/disk parameters
GO5 program: Water in Disks (PI: J. Carr)
-52 class II disks in multiple star-forming regions-Designed to cover a range of stellar/disk parameters-Subset of these disks + archived programs results in sample shown here
Sampled disks show significant variety
Pontoppidan et al., in prep
Pontoppidan et al., in prep
-Lines are actually spectrally uresolved line blends at the resolution of Spitzer-IRS -Lines probe a large range of excitation temperatures
Water vapor and organic emission is commonaround low-mass young stars
Pontoppidan et al. , in prep
Detection rates drop precipitously for SpT<G
Pontoppidan et al. , in prep
Transitional disks do not show emission
Emission of water correlates with CO emission
LTE models can be used to estimate density, T
But in general do a poor job of matching the data