(Sub)mm & Infrared Spectroscopy of

Circumstellar Disks

Geoffrey A. BlakeDiv. Geological & Planetary Sciences

59th OSU Symposium 25June2004

HD 141569A (HST ACS)

People Really Doing the Work!

Caltech: -Jacqueline Kessler (now at UT Austin), Joanna Brown -Adwin Boogert, Chunhua Qi (now at the SMA/CfA)

Leiden w/Ewine van Dishoeck & Michiel Hogerheijde: -Klaus Pontoppidan, Gerd Jan van Zadelhoff, Wing-Fai Thi (now at ESO)

25June2004

I. Why study disks?II. Mm-wave interferometry of protoplanetary disks.III. High resolution IR spectroscopy of disks.IV. Conclusions

Cloud collapse Rotating disk

infall

outflow

Planet formation Mature solar system

x1000 in scale

Adapted from McCaughrean

How are isolated Sun-like stars formed?

Picture largely derived from indirect tracers, especially SEDs.

Spitzer Space Telescope

- IRAC (mid-IR cameras, 3.6 4.5, 5.8, 8.0 m) - MIPS (far-IR cameras, 24, 70 160 m, R=20 SED mode) - IRS (5-40 m long slit,R=150, 10-38 m echelle, R=600)

August 2003 launch, >5 year lifetime.

- GTO observations

- Legacy program

- General observations25June2004

Evans et al., c2d~170 YSOs first look + follow up of mapping.

Meyer et al.Photometry~350 sources, IRS follow up (Class III).

Boogert et al. 2004, ApJS special issue

25June2004

HH 46 w/IRAC, IRS

Ices toward young low mass stars

Keck/VLT+Spitzer

Study Isolated Disks (Weak/No Outflow)

25June2004

Beckwith & Sargent 1996, Nature 383, 139-144.

Planet building phase

Why study disks? Star-disk-planet interactions:

Radial velocity surveys aresensitive to ~Jupiter/Saturnmass planets out to >5 AU.From whence hot-Jupiters?

Disk-star- and protoplanet interactions lead to migration while the disk is present.

The answer lies at earlier times…

Theory

Observation?

1 AU at 140 pc subtends 0.’’007.

Jupiter (5 AU):V_doppler = 13 m/sV_orbit = 13 km/sSimulation G. Bryden

Spectroscopy of “Disk Atmospheres”

25June2004

IR disk surface within several – several tens of AU(sub)mm disk surface at large radii, disk interior

G.J. vanZadelhoff2002

Chiang &Goldreich 1997

The 1-Baseline Heterodyne Interferometer:

•HST resolution at 1mm D=10 km! Use array.•Can’t directly process 100 – 1000 GHz signals.•Heterodyne receivers detect |V| and , noise defined by the quantum limit of h/k.•Positional information is carried by the PHASE.•Spectral coverage depends on the receivers, while the kinematic resolution is determined by correlator.

25June2004

Geometrical delay

The n-Element Heterodyne Interferometer:

•n(n-1)/2 baselines, imaging performance depends on the array geometry, but•For small to moderate n, the (u,v) plane is sparsely filled.•For a given array, the minimum detectable temperature varies as (resolution = S)-2 :

25June2004P = primary telescope beam

CO 3-2 CO 2-1

CO traces disk geometry, velocity field:

Qi et al. 2004, ApJL, in press.TW Hydra w/SMA

Disk properties vary widelywith radius, height; and depend on accretion rate,etc. (Aikawa et al. 2002, w/D’Alessio et al. disk models).

Currently sensitive only to R>80 AU in gas tracers, R<80 AU dust.

CO clearly optically thick, isotopes reveal extensive depletion, poor mass tracer!

The fractional ionization is >10-8, easily sufficient for MRI transport. HD & H2D+

(Ceccarelli et al. 2004) in midplane?

Disk Ionization Structure: CO and Ions

CO well mixed, while [CN]/[HCN] traces enhanced UV fields.Is LkCa 15 unusual?

Photodesorption?

Qi et al. 2004 & in prep

Chemical Imaging of Outer Disk?

HDO formed via H2D+, possible tracer of H3

+?

Kessler et al. 2004, in prep

(6 transits)

Ro=50AU Ro=300AURo=200AURo=100AU

For models: Using scaled H density distribution with varying inner radius cutoff

R0 Rout

NT

LkCa 15 HCN observations

Molecular Distribution Models

CO 2-1 from HD141569J.-C. Augereau & A. Dutrey astro-ph/0404191

Transitional/Debris Disks? HD141569 & Vega w/PdBI:

Vega, Wilner et al. 2002

Future of the U.S. University Arrays – CARMA

CARMA = OVRO (6 10.4m) + BIMA (9 6.1m) + SZ Array (8 3.5m) telescopes.

SUP approved!2004 SZA at OVRO2004 move 6.1m2004 move 10.4m2005 full operations

Cedar Flat 7300 ft. June 15th, 2004

March 27th , 2004

(pre-ALMA) The size scales are too small even for the largest current & near-term arrays. Spectroscopy to the rescue!

How can we probe the planet-forming region?

Theory

Observation?

Jupiter (5 AU):V_doppler = 13 m/sV_orbit = 13 km/s

High Resolution IR Spectroscopy & Disks

CO M-band fundamental

Keck

NIRSPECR=25000

R=10,000-100,000 (30-3 km/s) echelles (ISAAC,NIRSPEC, PHOENIX,TEXES)on 8-10 m telescopes can now probe“typical” T Tauri/Herbig Ae stars:

AB Aur

HD 163296

L1489:Gas/Ice~10/1, accretion.

CRBR2422.8:Gas/Ice~1/1, velocity field?

Elias 18Gas/Ice<1/10(Shuping et al.)

Edge-on absorption.

Orientation is Pivotal in the IR!

H2, H3+ in absorption?

25June2004

Spitzer Enables the Study of Edge-on Disks!

25June2004

VLT VLT

ISAACS

Flu

x (J

y)The small molecules in ices are similar in protostars and disks.

What about other species w/echelles?

25June2004

NGC 7538 IRS9

Boogert et al. 2004, ApJ, in press

Edge-on Disks & Comets?

IR studies of edge on disks will map out both gas phase & grain mantle composition, compare to that found in massive YSOs, comets.

N7538 W33A Hale-BoppWater 100 100 100CO 10 1 23CO2 16 3 6CH4 1 0.7 0.6H2CO 3 2 1CH3OH 9 10 2HCOOH 2 0.5 0.1 NH3 10 4 0.7OCS 0.1 0.05 0.4

25June2004

CO lines give distances slightly largerthan K-band interferometry, broad H I traces gas much closer to star (see also Brittain & Rettig 2002, ApJ, 588, 535;Najita et al. 2003, ApJ, 589, 931).Can do ~30-40 objects/night.

In older systems, CO disk emission is common:

Herbig Ae stars, from~face-on (AB Aur) to highly inclined (HD 163296).

CO lines correlated with inclination and much narrower than those of H I Disk!

Pf

Systematic Line Width Trends:•Objects thought to be ~face on have the narrowest line widths, highly inclined systems the largest.•As the excitation energy increases, so does the line width (small effect).•Consistent with disk emission, radii range from 0.5-5 AU at high J.•Low J lines also resonantly scatter 5 m photons to much larger distances.•Asymmetries (VV Ser)?

25June2004Blake & Boogert 2004, ApJL 606, L73.

CO and 13CO rotation diagramsshow curvature as a result of >1. Still, small amounts of gas since N(H2)~5 x 1022 leads to dust opacities near unity.

Collisional excitation important, but cannot explain line widths at low J values (too broad). Resonant IR scattering at larger radii!

The vibrational excitation is highly variable, likely due to variations in the UV field. Disk shadowing?

How is the CO excited in these disks?

25June2004

CO

13CO

Explanation:

Dust sublimation near the star exposes the inner disk to direct stellar radiation, heating the dust and “puffing up” the disk.

Flared disk models often possess 2-5 micron deficiency in model SEDs, where a “bump” is often observed for Herbig Ae stars.

Where does the CO emission come from?

Dullemond et al. 2002

25June2004

Calvet et al. 2002

For dust sublimation alone, the lines from T Tauri disks should be broader than those from Herbig Ae stars+disks. Often observed, but…

CO Emission from Disks around T Tauri Stars

The TW Hya lines are extremely narrow, even for a disk with i~7 degrees, imply R>2 AU. Gap tracer?

(Sub)mm-wave instruments can only study the outer reaches of large disks at present in lines; even at these wavelengths the disk mid-plane is largely inaccessible due to molecular depletion.

Expanded arrays (CARMA, eSMA, ALMA) will provide access to much smaller scales, lines should selectively highlight regions of planet accretion/formation. Midplane w/H2D+?

High resolution IR spectroscopy just starting, is immensely powerful, and provides unique access to the 0.5-50 AU disk surface before advent of ALMA, large IR interferometers. Spectra are esp. sensitive to disk geometry.

Spitzer is providing beautiful spectrophotometric SEDs and many new targets!

Disk Spectroscopy - ConclusionsDisk Spectroscopy - Conclusions

25June2004

AB Aur

HD 163296

Arrays everywhere!

25June2004

PdBI

VLA

SMABIMA

OVRO

ATCA

Typically ntel ≤ 6-10.

Embedded disks?

Padgett et al 1999

3mm: HCO+, HCN, 13CO, C180 (1-0) 2000 AU radius, 0.02 M disk 1mm: HCO+ (3-2) infall (disk not quite fully rotationally supported) 0.65 M M 1.4 M disk collapse to 300 AU in 2 x 104 yrs?

L1489, a disk in transition?

HCO+ 3-2 HCO+ 1-0

See also:Hogerheijde etal 1997, 1998;Looney 2000;Chandler & Richer2000, Shirley et al2000

Hogerheijde 2001

OVRO CO(2-1) Survey of T Tauri stars

• stellar ages 1 - 10 Myrs

• stellar masses ~ 1 M

• selection by 1 mm flux, SED characteristics

• Taurus 19/19 detections

• Ophiuchus 4/6 detections

• resolution ~ 2”

20 objects

radii 150 AU

masses 0.02 M

(from SEDs)

(Koerner & Sargent 2003)

See also Dutrey, Guilloteau,& Simon, Ohashi

Chemical / Radiative Transfer ModelingPhysical model: D'Alessio et al. 2001Chemical model: Willacy& Langer 2001Radiative transfer: Hogerheijde & vander Tak 2000

Molecular line surveyUV fieldsgrain reactions disk ages and evolution

Understanding Disk Chemistry

MM-Wave CO Traces Dynamics, Others?

25June2004

Dutrey et al. 1997, IRAM 30m

D. Koerner & A. Sargent OVRO, in

Qi et al. (2004).

Measure:R_diskM_starInclination

w/resolvedimages.

LkCa 15LkCa 15

The Sample (drawn from larger single dish + OVRO CO survey):

Star Sp Type d(pc) Teff(K) R(Rsun) L(Lsun) M(Msun) Age(Myr) LkCa 15 K5:V 140 4365 1.64 0.72 0.81 11.7 GM Aur K5V:e 140 4060 1.78 0.8 0.84 1.8HD 163296 A0 120 9550 2.2 30.2 2.3 6.0 MWC 480 A3 130 8710 2.1 32.4 2.0 4.6

Mannings, Koerner & Sargent 1997Mannings, Koerner & Sargent 1997

MWC 480

LkCa 15

Koerner & Sargent 1995

OVRO+CSO/JCMT MM-Wave Disk Survey

25June2004

Combine 3/1.3 mm array images w/higher J spectra to

constrain OUTER disk properties, chemical networks.

van Zadelhoff et al. 2001

OVRO+CSO/JCMT MM-Wave Disk Survey II

25June2004

Source L* (L ) CN/HCN H

dust/h

gas

LkCa 15 0.72 ~ 10 1.0GM Aur 0.80 << 1 4.0 MWC 480 30.2 ~ 4 1.7 HD 163293 35.2 >> 50 -

[CN]/[HCN] traces enhanced UV fields (Fuente et al. 1993,

Chiang et al. 2001)

Molecular distribution ring-like?

Photochemistry or desorption?

Qi et al., in prep

UV Fields: HCN and CN

LkCa 15

25June2004

Infinite resolution, complete UV coverage

Observed UV sampling, uniform weighting

CO 2-1 fitLkCa15 ___model - - -

Model Parameters i = 58°, Vturb= 0.1 km/s Ro= 5 AU, Rout= 430 AU nCO = 10-4 nH (D'Alessio 2001) syn = 3.6” x 3.6”

3.05.0 4.3 3.7

8.28.99.5

5.6

6.36.97.6

Modeling the effects of (uv) Sampling

MM-continuum surveys do not reveal such large, massive disks in similarly aged clusters (IC348) and clouds (NGC 2024, MBM12). Environment?

Need better (sub)mm-wave imaging capabilities. SMA! and…

CO, HCO+ (and NNH+) chemistry well predicted by disk models.

Other species, esp. CS, CN, HCN, much more intense, with unusual emission patterns in some cases (LkCa 15).

Are these large disks unusual?

29Aprn03

CARMA – Site Monitoring

HDO: rms (3sigma) = 0.05-0.1 K (CARMA w/D config. in 4 hrs)

ALMACARMA

Md=0.01Msun Rout=120AU Ro=20AU

Disk Observations w/CARMA+ALMA

Dust simulation (L.G. Mundy), unrealistic phase errors, but no CLEAN/MEM.

•Atm. fluctuations (mostly H2O) can vary geom. delay.•|V|eif decorrelation if Ef>each baseline).•If the fluctuations vary systematically across the array, phase errors ensue.•Problem is NOT solved.

OVRO WLM System

Atmospheric Phase Correction (mm Adaptive Optics)

Enter ALMA:

Llano de Chajnantor; 5000 m, good for astronomy, tough for humans!

Superb site & large array exceptional performance (64 12m telescopes, by 2012).

Dust simulation (L.G. Mundy), unrealistic phase errors, but no CLEAN/MEM.

Ices in the disk of L1489 IRS

• Prominent band of solid CO detected toward L1489, originating in large, flaring disk.

• CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures:

1 'polar' H2O:CO

2 'apolar' CO2:CO [NEW!]

3 'apolar' pure CO(Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

Nearly all spectra observed to date have emission from very high J levels (J>30-35), but…

Variations in CO M-band Spectra:

25June2004

The degree of vibrationalexcitation is highly variable!

This model can now be directly tested via YSO size determinations with K-band interferometry.

Intense dust emission pumps CO, rim “shadowing” can produce moderate T_rot.

Fits to AB Aur SED yield an inner radius of ~0.5 AU (and 0.06 AU for T Tau).

SED Fits versus IR Interferometry

(Monnier & Millan-Gabet 2002, ApJ)

Dullemond et al. 2002

Many other species and disk types (transitional, debris, etc.) should be examined in both absorption (edge-on disks) and emission, but extremely high dynamic range will be needed.

Protoplanet tracers?H2, H3

+, CH4, H2O, OCS... Line profile asymmetries?

Future “Near”-IR (1-5 m) Spectroscopy

Brittain & Rettig 2002, Nature