PProbing Planet Forming Disks:Clues to the Origins of Planetary Systems

INTRODUCTIONJoan Najita

National Optical Astronomy Observatory

John CarrNaval Research Laboratory

Matt RichterUC Davis

High Resolution MIR Spectroscopy of Planet Formation Environments

My Main Points

Forming planetary systems have a rich MIR spectrum•Discovered in the last 2 years (Spitzer + ground)•Emission and absorption

Observations address major Origins questions•Origin of prebiotic molecules and life•What kind of planets form in what kinds of disks?•Do stars form via dynamical infall?

Large discovery space (unanticipated science)

Origin of Prebiotic Molecules and Life

Were the “chemical building blocks” oflife delivered to Earth by asteroids andcomets?What prebiotics are synthesized in disks?

Complex hydrocarbonsAmino acidsRNA

What kind of disks form what kind of planets?

Low mass Jovian planet: Gap High mass Jovian planet: hole

Structure of gaseous disk more definitive than SEDsin identifying forming planets

Connecting initial conditions (e.g., disk mass) to outcomes (planetproperties) provides direct constraints on planet formation theories

Molecular Probes of Inner Disks

0.1 AU~1000 K

1 AU~200 K

10 AU~50 K

H2O ro-vib

CO Δv=2

CO Δv=1

H2 UV, NIR, MIR

OH Δv=1 HCN, CO2C2H2, OH, H2ONH3

Rich MIR spectrum probes the planet formation region

S/N ∼ 250Atomic lines [NeII], HIMolecules C2H2, HCN, CO2

H2O, OH

Carr & Najita (2008)

Spitzer IRS Spectrum of a Typical T Tauri Star

Molecular Emission is Common, Diverse

C2H2 CO2HCN•Relative strengths of molecularfeatures vary.

•Abundances are diverse.

log (HCN/H2O)

log

(CO

2/H 2

O)

T Tauri stars

Comets

H2O Rotational Emission Line Resolved

13µm

Line profiles, temperatures, and emitting areas indicateorigin in planet formation region of disk

Water emission resolved:90 km/s FWHMFrom r = 0.3--1 AU

H2O (12,8,5)—(11,5,6)

Gemini/TEXES R=100,000

Carr, Knez, Richter, Knez et al.

Spitzer/IRS R=600

MIR Molecular Emission

Rich emission from planet formation region:• Organics, water, atomic emission is common• Relative molecular abundances are diverse

Spectroscopy of multiple lines measures vs. disk radius• Temperature• Column density, and• Abundances

This basic technique enables a wide range of studies(disk dynamics, structure, chemistry).

Spitzer MIR Molecular Absorption

Nearby T Tauri Starw/ edge-on diskobserved with Spitzer/IRS

Absorption in gaseousHCN, C2H2, CO2

Courtesy: Spitzer IRS GTOs

MIR Molecular Absorption: High Res

Gemini/TEXES (R=100,000)FWZI ~ 20 km/s

Can detect molecules w/ostrong bands that Spitzerdoes not detect

NH3 NH3NH3

C2H2 HCN

MIR Molecular Absorption

High spectral resolution needed to know if absorption in…•Disk atmosphere (narrow, at zero velocity)?

•Infall from cloud core (redshifted)? •Wind (blueshifted)?

Abundances and column densities of each are interesting.•Disk: rarer species detectable, complements emission

•Infall: detection, measure infall rate and abundances

•Wind: disk wind or X-wind?

Molecular Inventories

Pre-InfallDisksCometsRelative

Abundances

8100100100100100H2O

Orion HotCore

Inner DiskAtmospheres

Hale-BoppHyakutakeHalley

Starting to probe molecularprocessing in disks!

MIR Accessible MoleculesH2H2O waterHDOH2O2OHSiOOCSSO2H2SSiSH2CO formaldehydeCH4 methaneCH3D CH3 methyl radicalC2H2 acetylene HCN hydrogen cyanideHNCO isocyanic acidNH3 ammonia

C2H4 ethyleneC2H6 ethaneC4H2C6H2 C3H8 propaneCH2CCH2 propadieneC6H6 benzeneHCOOH formic acidCH3OH methanolHN2CHO formamideHC3CHO acetaldehydeCH3COOH acetic acidHCOOCH3 methyl formateCH2OHCHO glycoaldehydeC2H5OH ethanol(CH3)2CO acetoneHOCH2CH2OH ethylene glycolNH2CH2COOH glycine

Detected with TEXES

Future MIR Science•Search for prebiotic molecules in disks, infall

•High res GSMT spectra resolves blends, measures disk radii

•Search for evidence of planetesimal and protoplanet formation using disk abundances. (NEW!)

•GSMT line profiles establish inner disk origin for bright srcs•JWST measures H2O+organics abundances for large samples

•Search for disk gaps created by forming giant planets.•GSMT line profiles measure column density deficits

•NeII 12.8µm as a probe of disk gas lifetime (constrains giant and terrestrial planet formation theories).

•GSMT line profiles measure disk radii probed by NeII•JWST surveys large samples for NeII flux

GSMT and Precursor StudiesTEXES/Gemini or VISIR/VLT:• study bright emission lines in isolated environments (NeII, water w/in 150 pc)• absorption in a few bright sources

High Resolution MIR Spectroscopy with GSMT:• search for rarer molecules w/in 150 pc• study bright emission (water, NeII) in high mass star environments (out to 500 pc)• absorption in a real sample

Pathfinding studies possible now, but GSMT sensitivityneeded for the most significant discoveries

Synergy of JWST, ALMA, and GSMT

JWST/MIRI high spectral resolution (R=3000) important:• resolve some blends, detect weaker lines (not just water)• individual lines not resolved

R=100,000 Spectroscopy with GSMT•resolve blends, detect weak features•Separate disk, infall, winds with line profile shape•Measure column density and abundance vs. radius

ALMA studies cooler gas at larger disk radii

GSMT Requirements forHigh Resolution MIR Spectroscopy

•Large wavelength coverage•Queue scheduling (water vapor, Doppler shifts)for some transitions

Observations address major Origins questions•Origin of prebiotic molecules and life•What kind of planets form in what kinds of disks?•Do stars form via dynamical infall?

Large discovery space (unanticipated science)

My Main Points

Planet forming systems have a rich MIR spectrum

•MIR a desert “in bloom”•Emission and absorption