Gas in Protoplanetary DisksGas in Protoplanetary Disks

Thomas HenningMax Planck Institute for Astronomy, Heidelberg

Frontiers Science Opportunities with JWST, Baltimore, 2011

Planet Formation: StagesPlanet Formation: StagesS

tar

& c

ircu

mst

ella

r (o

r p

roto

pla

neta

ry)

dis

k

Dynamicalrestructuring

In presence of gas In absence of gas

dust

This Talk

• How much time do we have to form planets?

• Can we find water and organic molecules in disks?

• What can we do with JWST?

The Disk Structure

Small Structures – Low Mass – Low line/continuum ratio

The Gas Disks

• Angular momentum and mass transport

• Dynamics of dust and planets (Coagulation/Migration)

• Reservoir for the formation of molecules

Water on Earth

• „Wet“ Formation (Drake 05)

• „Dry“ Formation (Morbidelli et al. 00)

3D Global Stratified MHD Simulation

Radius:1-10 AU

8 pressure scale heights

Blue Gene/P and Pluto code: Flock et al. (2011)

Ionization structure of a T Tauri disk(Semenov, Wiebe, Henning, 2004, A&A, 417, 93)

„Layered“ vertical structure

Mixed grains(dead zone)

Sedimentation

See alsoIlgner & Nelson(2006, 2007)

Disk mass and planet mass

Log(Mdisk/MMSN)

Plan

et m

ass

[Jov

ian

mas

ses]

Maximal planetmass increases with disk mass.

Mplanet=0.5 Mdisk

Mordasini et al. , submitted.

PAHs in Protoplanetary Disks

(Acke, Bouwman, Juhasz, Henning et al. 2010)

(Geers et al. 2007, RR Tau)

Dust and GasDisk Lifetimes

Haisch et al. (2001), Hernandez et al. (2008), … Fedele et al. (2010), …

FEPS Spitzer

Legacy IRS

survey20 stars

with ages 3-

100 Myr

=> No gas

rich disks

(> 0.1 MJup)

detected. Hollenbach et al. (2005),Pascucci et al. (2006)

See also: Ingleby et al. (2009)

Gas Disk Lifetimes < 10 Myr

Different stages of disk evolution~

10

Myr

~1

Myr

V(km/s) log(/ m)

H

H

H

V(km/s) log(/ m)

V(km/s) log(/ m)

Typical CTTS

Flattened, accreting disk

Non-accreting TO

A molecular disk at its edge

• CO emission at 4.7 μm• Gas in Keplerian orbit• Inner cavity (r~11 AU)• Coming closer to the star than HST

• CO emission at 4.7 μm• Gas in Keplerian orbit• Inner cavity (r~11 AU)• Coming closer to the star than HST

Goto et al. (2006)

HD 141569A

LkCa 15 – The SEEDS CollaborationLkCa 15 – The SEEDS Collaboration

What physical object is it that we see as a What physical object is it that we see as a bright crescent? Two possibilities:bright crescent? Two possibilities:

Offset between nebulosity center and star suggests eccentric outer disk; this is Offset between nebulosity center and star suggests eccentric outer disk; this is expected from dynamical influence of planets, and hard to explain otherwise.expected from dynamical influence of planets, and hard to explain otherwise.

Illuminated wall of Illuminated wall of the disk on the far the disk on the far side.side.

Forward-scattering Forward-scattering on near-side disk on near-side disk surface.surface.

Thalmann et al. 2010Thalmann et al. 2010

Espaillat et al. 2008Espaillat et al. 2008 Thalmann et al. 2010Thalmann et al. 2010

Disk Chemistry

• Large range of temperatures and densities

• Importance of stellar and interstellar radiation fields Ionization and heating sources: Cosmic rays, UV radiation, X-rays, extinct radionuclides

• Strong coupling between chemistry and dynamics (ionization, temperature structure, cooling)

Dust and gas strongly coupled …

Disk Structure

~500 AU100 AU0.03 AU

~1000 AU

0

Observable region with interferometers

photon-dominated layer hν, UV, X-rays

turbulent mixing

IS UV, cosmic rays

Snowline (T=100K)

puffed-upinner rim

accretionwarm mol. layer

cold midplane

How to produce simple hydrocarbons?

Gas-phase chemistry allows to build up simple moleculesthat can later freeze out or are ‘used’ to form larger species

radiative association

reactions with C

Spectroscopy - An Essential Tool

ISO SWS disk spectrum of the Herbig Ae star HD 100546 (Malfait et al. 1998) and comet Hale-Bopp (Crovisier et al. 1997) for comparison

(Background)

Apai et al. (2005); Flux at mJy level Pontoppidan et al. (2005)

DRM Documents, MISC Report,August 22nd, 2001

H2 is a challenging molecule to detect

Rotational lines between5.05 µm and 28.22 µm

Bitner ea. (2007, AB Aur)Martin-Zaidi ea. (2009, HD 97048)

See also Carmona ea. (2008)

Not sensitivity, but disk structure! We use tracers for obtaining information about the gas.

The Disk Tracers

• Atomic and ionic fine structure lines ([NeII], [SiII], [SI], …)• Diagnostic features of PAHs (11.3 microns) and dust grains• Molecular lines (H2, H2O, CO2, …)

(Gorti and Hollenbach 2008, Star of 1 Ms)

Observational constraints

• UV: H2 emission from hot inner disks

• Optical wavelengths: [OI] emission

• IR: H2, CO, H2O, OH, … in warm inner disk (1-10 AU) and molecular ices in outer disk, key organic species CH4 (7.7 µm), C2H2 (13.7 µm), HCN (14.0 µm)

• FIR: CO, OH, … in warm outer disk surface

• (Sub)mm: CO and isotopes, HCO+, DCO+, CN, HCN, DCN, HNC, N2H+, H2CO, CS, HDO (?), CH3OH, CCH in cold outer disks (»10 AU)

Spectroscopy at sub-mm wavelengths

Dutrey et al. 1997

Thi et al. 2004;Kastner et al. 1997

CID @ PDBI:Dutrey ea. 07, Schreyer ea.08,Henning ea. 10, ….DISCS @SMA: Öberg ea. 10, 11

Molecular Abundances in Disks

10-9

10-8

10-7

10-6

10-5

10-4

Log

10 (

Abu

ndan

ce R

el. t

o H

2)

CO HCN HNC CN CS H2CO HCO+ C2H

DM Tau Disk Mol. Cloud

Strong depletion of gas-phase species: radiation or freeze-out?

IR Spectroscopy Reveals Complex Chemistry

HCN and C2H2 detected around a young low-mass star

T 350 K ≳ Abundances several orders of magnitude higher than ISM

dark clouds Production in inner (< 6 AU) disk or wind

(Lahuis et al. 2006 IRS 46 in Ophiuchus; Variable) see also Gibb et al. 2008 for GV Tau)

700 K 400 K 300 K

Organic Molecules and Water

Pascucci et al. (2009) Carr & Najita (2008)

N atoms from photodissociation of N2

Diversity in inner disk atmosphere chemistry (e.g. Pontoppidan ea. 10, Carr & Najita 11, Teske ea. 11)

Water in Protoplanetary Disks

• Dominant line-cooling of inner disk surfaces (~10-4 Lsun) (Pontoppidan et al. 2010)

• No H2O, but OH detection in Herbig Ae/Be disks – Photodissociation of water by FUV photons (Pontoppidan et al. 2010, Fedele et al. 2011)

• Mid-infrared lines come from ~1 AU with rotional temperatures between 500 and 600 K

• No detection of colder water vapor in outer disk regions with Herschel (Bergin et al. 2010)

VLT/VISIR: Pontoppidan ea. (10)

Abundance of water is getting higher in mid-Abundance of water is getting higher in mid-plane and in intermediate warm disk layer. plane and in intermediate warm disk layer. Maximum of abundance shifts deeper into Maximum of abundance shifts deeper into the disk which may prevent water vapor the disk which may prevent water vapor

from being observed.from being observed.

Vasyunin, Henning et al. (2011)

Dust Evolution and Water Abundance

HD 100456 with Herschel

Sturm, Bouwman, Henning et al. (2010; see also Thi et al. 2011)

CO, [OI], [CII], CO, H2O, CH+, …

Key Science Questions for JWST

• Inner Gaps and Radial Structure of Outer Disks

• Vertical Disk Structure (Gas-Dust Physics and Chemistry)

• Content of Water and Organic Molecules in Disks

Fukagawa et al. 2004

Disk structure

Spectroscopy Imaging

Dust settling revealed by imaging

PAH

Image in PAH and dust continuum bands

Imaging gaps in transitional disks

VLT VISIR image8.6 PAH 11.3 PAH19.8 m large grains

Geers et al. 2007Ratzka et al. 2007Brown et al. 2008. 2009Pontoppidan et al. 2008Eisner et al. 2009Thalmann et al. 2010

IRS48

SR 21

Examples of disks known to have big enough gaps (~40 AU) to resolve with MIRI imaging and IFU

Vertical Protoplanetary Disk Structure

Mid-IR gas lines trace various depths in the disk (temperature and density profiling)

Gas-dust physics (e.g. sedimentation) and thermal structure

Key factors: Stellar irradiation characteristics, grain/PAH evolution, chemistry

Surface density and disk mass kept constant; Dashed lines: AV=1, 10 mag contours

Uniqueness of MIRI/MRS

High spectral resolution, high sensitivity, continuous coverage:

• line-to-continuum ratio sufficient to detect minor species (res: 2000-3700) • extend studies to faint brown dwarf disks (mJy @ 10m)

[Fred Lahuis][Fred Lahuis]

Inventory of Organic Molecules in Disksof Various Evolutionary Stages

• Key organic molecules such as CH4, C2H2, HCN, …• Sample can be based on previous characterization with Spitzer/IRS, Herschel/PACS and Herschel/HIFI

Hydrogen rotational lines

Hydrogen deuteride rotational lines

Hydroxyl radical rotational lines entire range

Water rotational lines entire range

Carbon dioxide

Acetylene

HCN Hydrogen cyanide

HNC Hydrogen isocyanide

Sulfur dioxide

Carbon disulphide

Methane

Methyl radical

Ammonia

HNCO Isocyanic acid

Ethane

Benzene

Formyl ion

Methanol

H2 λ = 5.05 – 28.22 μmHD λ = 11.5 – 28.50 μmOH

H2O

ν2 ro-vibr. band λC = 6.27 μm

CO2 ν2 ro-vibr. band λC = 15.0 μm

C2H2 ν5 ro-vibr. band λC = 13.7 μm

ν2 ro-vibr. band λC = 14.0 μm

ν2 ro-vibr. band λC = 21.6 μm

SO2 ν3 ro-vibr. band λC = 7.34 μm

CS2 ν2 ro-vibr. band λC = 25.2 μm

CH4 ν4 ro-vibr. band λC = 7.66 μm

CH3 ν2 ro-vibr. band λC = 16.5 μm

NH3 ν2 ro-vibr. band λC = 10.5 μm

ν4 ro-vibr. band λC = 12.9 μm

C2H6 ν9 ro-vibr. band λC = 12.2 μm

C6H6 ν4 ro-vibr. band λC = 14.8 μm

HCO+ ν2 ro-vibr. band λC = 12.1 μm

CH3OH ν8 ro-vibr. band λC = 9.68 μm

HNC, CH4, CH3,C2H6, CH3OH, …to be detectedwith MIRI

The Water Reservoir

MIRI water lines come from an inner dense region

Woitke et al. (2009)

The Power of the MIRI IFU

F. Lahuis

Conclusions

• Rapid dust and gas evolution

• Rich molecular chemistry in planet-forming disks

• Diversity in abundance of organic species

• Transition disks and exoplanets

• Bright future: ALMA, 30-40m class telescopes, JWST

M. Barlow, D. Barrado, W. Benz, J. Blommaert, A. Boccaletti, J. Bouwman, L. Decin, A. Glauser, M. Güdel, Th. Henning, I. Kamp, P.-O. Lagage, F. Lahuis, G. Olofsson, E. Pantin, J. Surdej, T. Tikkanen, E. van Dishoeck, H. Walker, R. Waters,

B. Vandenbussche ISO+Spitzer+HST+Chandra+Herschel+VLT/VLTI+IRAM/JCMT/SMA/VLA+Modeling

MIRI Science Disk TeamImaging and Spectroscopy of PP Disks