Geoffrey A. BlakeGPS Division

Astronomy Colloqium, 26October2005, Caltech

VV Ser

Spιtzer+Keck Spectroscopy & the Building Blocks of Planetary Systems

Talk Outline:

26Oct2005

I. Why do we care about chemistry & star/ planet formation?

II. What has Spitzer imaging told us? - Low mass end, timescales.

III. What about the dust+ice and gas? - Keck & Spitzer IRS.

IV. What might the future hold in store?

People Really Doing the Work!

Caltech: -Adwin Boogert, Joanna Brown, Colette Salyk

Leiden w/Ewine van Dishoeck & Michiel Hogerheijde: -Klaus Pontoppidan (now at Caltech), Jes Jørgensen, Fred Lahuis (SRON), Kees Dullemond (MPI)

c2d: -UT Austin (N.J. Evans, P.I.), Caltech/JPL, Harvard Smithsonian, Leiden, UMaryland, Northern Arizona

26Oct2005

We have dreamed of extrasolar planets for a long time, …

English engraving 1798 (and Physics Today 4/2004).

Why chemistry & developing systems? I:

…with spectroscopy, we can now detect them!

Radial velocity surveys aresensitive to ~Jupiter/Saturnmass planets out to >5 AU,Neptune masses further in.

http://exoplanets.org/exoplanets_pub.html

Disk-star- and protoplanet interactions lead to migration while the gas is present. Core- accretion & ice?

Why do we care about gas & ice in disks?

Theory

Observation?

1 AU at 140 pc subtends 0."007.

Jupiter (5 AU):Vdoppler = 13 m/s

Vorbit = 13 km/sSimulation G. Bryden (JPL)

From whence volatiles?

Late planetesimal accretion from the outer solar nebula?

Why chemistry & developing systems? II:

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.

How do we probe gas/dust of solar composition?

26Oct2005

He

HO

CN

Si

AllElse

Fe

Use dust, chemistry.

• Infrared Great Observatory– Background Limited Performance 3 - m– 85 cm f/12 Beryllium Telescope, T < 5.5K– 6.m Diffraction Limit– New Generation Detector Arrays– Instrumental Capabilities

• Imaging/Photometry, 3-180 m

• Spectroscopy, 5-40 m

• Spectrophotometry, 50-m

– Planetary Tracking, 1 arcsec/sec– >75% of observing time for the

General Scientific Community– 2.5 yr Lifetime/5 yr Goal – Launched in August 2003 (Delta 7920H)– Solar Orbit– $450 M Development Phase Cost Cap

• Cornerstone of NASA’s Origins Program

What is Spitzer?

Extra-galactic Legacy Programs

• Great Observatories Origins Deep Survey (GOODS)– M. Dickinson (STScI) and 40 co-Is at 14 institutions– Deep 300 square arcmin IRAC and MIPS (24 microns) survey overlapping

HST and CXO deep fields– Galaxy formation and Evolution, z = 1– 6

• The SIRTF Wide-area Infrared Extragalactic Survey (SWIRE)– C. Lonsdale (IPAC/CIT ) and 19 co-Is at 9 institutions– ~100 sq. deg., high latitudes, reaching z ~ 2.5– Evolution of dusty, star-forming galaxies, AGN

• The SIRTF Nearby Galaxies Survey (SINGS): Physics of the star-forming ISM and Galaxy Evolution

– R. Kennicutt (Arizona) and 14 co-Is at 7 institutions– Imaging and spectroscopy of 75 nearby galaxies– Connections between ISM and star formation, templates for high z

Galactic Legacy Programs

• The SIRTF Galactic Plane Survey (GLIMPSE)– E. Churchwell (Wisconsin) and 13 co-Is at 6 institutions– 240 square deg. IRAC survey of inner Galactic plane– Galaxy structure and star formation

• From Molecular Cores to Planet-forming Disks (c2d)– N. Evans (Texas) and 10 co-Is at 8 institutions– Imaging (IRAC and MIPS) and spectroscopy of star forming regions– Evolution of molecular cores to stars, disks, sub-stellar objects

• The Formation and Evolution of Planetary Systems: Placing our Solar System in Context (FEPS)– M. Meyer (Arizona) and 18 co-Is at 12 institutions– Imaging and spectroscopy of 300 young stars with disks– Evolution from accretion disks to planet formation

From Cores to Disks (c2d) – N.J. Evans, P.I.

c2d Observations

• (275 hr) IRAC and MIPS Mapping– Map 5 large clouds (~20 sq. deg.) [Obs. done, being analyzed]– ~88 smaller cores [obs. Just completed, being analyzed]

• (50 hr) IRAC and MIPS Photometry– ~190 stars [obs. nearly finished, being analyzed]

• (75 hr) Spectroscopy of disk material (IRS) – about 200 targets [about 2/3 obs., being analyzed]

• Ancillary/complementary data from optical to mm– Collecting a very large data base– Will be publicly available [eventually]

Spitzer image of VV Ser region: B=IRAC 2 G=IRAC 4 R=MIPS 1

What can we learn?• The initial conditions for collapse

– Study starless cores (extinction mapping, …)

• The full population of young stellar objects (YSOs)– Sensitive surveys, can find rare objects

• Timescales for various stages– More complete, less biased surveys

• How low in mass do YSOs extend?– Use Spitzer MIR sensitivity to detect low-mass disks

• Timescales for disk evolution– Study large sample of stars (excess vs. age)

• How do the building blocks of planets evolve?– Evolution of dust, ice, gas

Perseus as seen by IRAC

3.6, 4.5, 8.0

NGC1333

IC 348

Perseus / NGC1333 Perseus / IC348

The Well Known Cluster Regions (courtesy L. Allen)

Very Low-mass Objects

Allers et al. 2006, in prep. (Ophiuchus)

Fits model atmosphere of brown dwarf (purple line):(~40 Mjup)

Has MIR excess:Fits model of disk(green line).

c2d mapping sensitive down to 1-2 Mjup in Oph, Cha. Need deep optical data!

HH 46

L1014

Spitzer/IRS’s Forte – High Sensitivity Spectra…

IRS (5-40 m long slit, R=150,

10-38 m echelle, R=600)

L1014 (substellar)

Young, deeply embedded protostars in Perseus:

H2O CH4 Silicates

Extraordinary extinctions/ice bands!

What ices are present?

Ices Can Be Complex Early!

Minor species:Blue: with silicate removedBlack: with H2O ice also removedRed: fit with HCOOH and 6.8 m carrier

Knez et al. 2005

Protostars & Comets?

Spitzer+Keck studies are mapping out both gas phase & grain mantle composition, comparable to that found in massive YSOs, comets.

Clouds are “primed” with ices that can form complex organics, even before star formation.

HH46 W33A Hale-BoppWater 100 100 100CO 20 1 23CO2 30 3 6CH4 4 0.7 0.6H2CO … 2 1CH3OH 7 10 2HCOOH 2 0.5 0.1 NH3 9 4 0.7OCS … 0.05 0.4

26Oct2005

Cloud collapse Rotating disk

infall

outflow

Planet formation Mature solar system

x1000 in scale

Adapted from McCaughrean

What about older, visible stars & disks?

Picture largely derived from indirect tracers, especially SEDs.

Classical T Tauri Stars

Strong evidence for intense near- through mid-IR excess, bigger than expected.

Requires extra flux; likely due to accretion shock. Corroborated by PTI & KI K-band sizes.

Cieza et al. 2005 in press

Spectroscopy of “Disk Atmospheres”

26Oct2005

IR disk surface within several 0.1 – several tens of AU(sub)mm disk surface at large radii, disk interior

HD 141569

The Radial & Vertical Chemical Structure of Disks

X-rays

Grain Growth in Disks10 m band 20 m band

Models

Data

Kessler-Silacci et al. 2006, in press

Grain Growth in Disks II – Edge on Disks

Shape and depth of mid-IR “valley” very sensitive to grain size. For this source, grains at least ten m in size are inferred.

“Flying Saucer” Grains >10 m at disk the photosphere must be lofted.

Goldreich-Ward instability for planetesimal formation inhibited?

Can ices be seen in edge-on disks?

26Oct2005

VLT

Flu

x (J

y)

ISAAC

Yes, & the small molecules in ices are similar in protostellar envelopes and disks.

Crystalline Silicates in DisksISO SWS – HAe Stars

Spitzer – Brown Dwarf!

An intense central source of wind/ radiation is not required to anneal silicates. Products of planetesimal collisions? Companions?

“Age

”

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

How can we probe gas in the planet-forming region?

Theory

Observation?

Jupiter (5 AU):Vdoppler = 13 m/s

Vorbit = 13 km/s

High Resolution IR Spectroscopy & Disks

CO M-band

Keck

NIRSPECR=25,000

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:

TW Hya

L1489IRS

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 ~20-30 objects/night.

In older/inclined systems, CO disk emission:

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

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/Muzerolle et al. 2004

26Oct2005

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 Trot.

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

Testing the Model: Line Width Trends

26Oct2005Blake & Boogert 2004, ApJL 606, L73.

AB Aur

VV Serinclination

•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)?

Gas and dust radii are comparable, to first order. How is the CO protected if the dust sublimates at smaller radii?

CO gas radii versus stellar luminosity.

Do T Tauri stars behave similarly?

Dullemond et al. 2002/Muzerolle et al. 2004

26Oct2005

Do ices evaporate in disks, & to what effect?

26Oct2005

UV

Hot Core

complex organics

T (gas) = 200 - 1000 K

~1016 cm

T (dust) ~90 K~90 K ~60 K~60 K ~45 K~45 K ~20 K~20 K

SiO

H2O, CH3OH, NH3

H2S

CH3CN

~5x1017 cm

H2O ice

CO2

CON2

O2

iceCO2

icetrappedCO

CH3OHice

IRS 46

CRBR 2422.8

Hot cores & massive YSOs.

Can verify evaporation in hot cores w/echelles:

26Oct2005

NGC 7538 IRS9

Boogert et al. 2004, ApJ 615, 344

Disks?

T=300-700 K. Is this grain mantle evaporation only, or does gas phase chemistry play a role?Need high resolution spectra!

A pleasant surprise: IRS 46

26Oct2005

IRS 46

CRBR 2422.8

Spitzer IRS R=600 Short Hi Data

C2H2 HCN CO2

IRS 46 complementary data

JCMT HCN J=4-3

- Spitzer-IRS data indicate huge column density (>1016 cm-2) of hot HCN- Keck data show hot HCN and CO blue-shifted by 25 km/s- Submm lines optically thick expect 400 K line if emission fills beam- JCMT 4-3 spectrum indicates at most 0.02 K emitting size <11 AU

Keck HCN 3 m and CO 4.7 m

Hot chemistry in inner 10 AU of disks

- Model of flared disk with puffed up inner rim , seen at inclination ~70o

- Line of sight through puffed-up inner rim. Need to measure vstar- Produces large enough column and T- HCN and C2H2 abundances ~10-5 w.r.t. H2

Probe of chemistry in planet-forming zones?

An amazing variety of organics are found in chondrites, including a wide variety of aliphatic and aromatic hydrocarbons, carboxylic acids, amino acids, purines, pyrimidines, and sugars. Synthesis?

From whence the complex nebular organics?

D values are large, structural diversity complete. Supposedly formed by aqueous alteration of ISM precursors on parent bodies, but organic and silicate aqueous signatures are contradictory. Can the organics be made in the disk? The oxygen fugacity is critical.

Is there steam? If so, how might we find it?

26Oct2005

THz Uniquely sensitive to first row atoms, hydrides, torsions. Cannot resolve spatially, need sub-km/s spectra.

Tera incognita!

Herschel

Calvet et al. 2002

For a few T Tauri stars, the relative lack of mid-IR flux is often attributed to gaps induced by planet formation. Rare, so must be a short- lived phase. How to test?

More evolved sources: Do SED dips demand gaps?

The TW Hya lines are extremely narrow, with i~7° R≥0.4 AU. Similar for SR 9 and DoAr 44, but gas radius << dust radius (SED)?Recall hCO ≥ 11.09 eV to dissociate.

(R<24 AU)

(R<4 AU)

Calvet et al. 2005

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 Transitional Disks?

The TW Hya lines are extremely narrow, with i~7° R≥0.4 AU. Similar for SR 9, DoAr 44, GM Aur but gas radius << dust radius (SED)?Recall hCO ≥ 11.09 eV to dissociate.Gas rich, but extensive grain growth.

Other gap/grain tracers? What can mm-waves tell us?

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

Chiang &Goldreich 1997

HH 30

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>50 AU in gas tracers, R<50 AU dust.

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

The fractional ionization is ≥10-9, easily sufficient for MRI transport.

Current mm-arrays & disk structure:

Qi et al. 2003

Future of U.S. University Arrays – CARMA

CARMA = OVRO (6 10.4m) + BIMA (9 6.1m) + SZA (8 3.5m) arrays

2004 SUP approved!2004 SZA at OVRO2004 move 6.1m2005 move 10.4m2006 full operations2008 merge w/SZA

Cedar Flat 7300 ft.

March 29th, 2004

August 12th, 2005Spectral line fringes, October 17th, 2005

CARMA 2008: BIMA+OVRO+SZA =

dramatically improved (uv) coverage, …

OVRO SZA CARMA + SZA

Md=0.01 M Rout=120 AU Rin=20 AU

L.G. Mundy

… and fidelity! Mel Wright, http://www.mmarray.org/memos/carma_memo27.pdf

10"

230 GHz

CARMA-23 C&D+SZA w/3.5-6.1m spacings

Fidelity~200

CARMA-15 A+B

•Spectra of embedded/edge-on Sun-like protostars can be studied in the IR for the first time with Spitzer+8-10m telescopes.•The ice composition is remarkably similar in all stages, and can drive a rich organic chemistry if the oxygen fugacity is low. Water? (Herschel)•Grain growth is ubiquitous, silicate annealing can be seen even in brown dwarf disks. Due to planetesimal collisions? Planetary companions?•Expanded mm-arrays (CARMA, eSMA, PdBI, ALMA) will provide access to much smaller scales, and should be able to image the larger gaps proposed for some transitional disks.

Spectroscopy & Developing Planetary Systems - ConclusionsSpectroscopy & Developing Planetary Systems - Conclusions

AU Mic

HH46

VV Ser