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