Chemical Processes in Protoplanetary Disks ~ Water, Snowlines & Organic Molecules ~

DTA Symposium June 1-4, 2015 @ NAOJ

Hideko Nomura  (TITECH)

§1 Introduction

Subaru

(ALMA partnership 2015)

ALMA

Gas & Dust Observations in PPDs

HL Tau (Brogan+ 2015)

(Fukagawa+ 2013)

HD142527

TW Hya (Qi et al. 2013)

SAO206462 (Muto+ 2012)

DCO+ 5-4 HD163296 (Mathews et al. 2013)

N2H+ 4-3

ALMA

Subaru

Observationally diagnosing physical & chemical structure of

planet-forming regions

Obs. of Gas in Protoplanetary Disks

12CO, 13CO, C18O, HCO+, H13CO+, DCO+,

C2H, c-C3H2, H2CO, HCN, HNC, DCN, CN, N2H+, HC3N, CH3CN,

CS, C34S, etc.

(sub)mm

H2 v=1-0 S(1), S(0), CO Δv=2, Δv=1, etc.

H2 Lyman-Werner band transitions

Optical[OI] 6300A

[OI] 63um, 145um, CO, H2O, CH+, HD, etc.

(Herschel Space Observatory)

H2O, OH, HCN, C2H2, CO2 (Spitzer Space Telescope)

FIR

H2 v=0-0 S(1), S(2), S(4)

NIR

MIR

UV

★

(sub)mm infrared

→ALMA

Chemical Models of Protoplanetary Disks Chemical reaction network + Physical model of PPDs - Include physical processes : dust evolution & gas motion - Include various chemical reactions: dueterated species, grain surface chemistry, etc.

Grain growth Comparison between model & obs. → Physical structure of PPDs &

Origin of materials in our Solar System

Contents§1. Introduction

§2. Water & Snowlines in PPDs -  Detecting H2O snowline in PPDs -  C/O ratio distribution in PPDs ~ Exoplanet formation process~

-  Deuterated water

§3. Formation of Organic Molecules in PPDs

§4. Summary

§2 Water & Snowlines in Protoplanetary Disks

H2O Snow Line & Planet Formation

ESA

Halley

H2O, CO2, CH4, CH3OH, H2CO, NH3, HCN, etc.

(e.g., Markwick+2002, Aikawa+ 2002, Bergin+ 2007, Dutrey+ 2014)

H2O snow line

H2O snow line divides rocky planet & gas giant forming regions

Obs. of water lines from PPDs

hot MIR lines

warm FIR lines

cold FIR lines

AA  Tau  Spitzer/IRS  

(Carr  &  Najita  2008)  

H2O,  OH,  HCN,  C2H2  TW  Hya  

(Hogerheijde+  2011)  

Herschel/HIFI  (Riviere-­‐Marichalar+  

2012)  

AA  Tau  Herschel/PACS  

[OI]   H2O  

Herschel cold H2O @267µm, 539µm, TW Hya, HD100546

Spitzer hot H2O@10-35µm, TTSs: detect, HAEBEs: upper limits Herschel warm H2O TTSs, HAEBEs: @55-180µm

　H2O snow lines in PPDs

(Zhang+ 2013)

TW Hya Spitzer/IRS

Herschel

Inner hole

Spitzer/IRS

H2O Snow line @ ~4AU H2O Snow line @ ~1AU (Meijerink+ 2009)

model

model with snow line

AA Tau

DR Tau

AS 205 PACS HIFI

H2O line ratios + disk model → predict H2O snow lines

The results are model dependent…

Outside snow line�

Inside snow line

1 10 100 0

0.2

0.4

0.6

0.8

1.0e-18

1.0e-16

1.0e-14

1.0e-12

1.0e-10

1.0e-08

1.0e-06

1.0e-04

1.0e-02

Kepler rotation

(Notsu+ in prep.)

H2O Snow Line by High-R. Obs.

H2O  Abundance

H2O snow line will be detected using high-R (R~100,000) spectroscopic observations

(ALMA, TMT, SPICA, …)

Disk Radius [AU]

Dis

k he

ight

/ R

adiu

s

H2O  17.8μm  Tota

l Int

ensi

ty [

Jy]

Fast Pebble Growth @ Snow Lines?

Grain growth @ snow lines?

HL Tau (Brogan+ 2015)

ALMA 1.3mm

233/343GHz Grain

growth?

(Zhang et al. 2015)

H2O

CL NH3, etc.

CL CO, N2

CO Snow LineSMA

CO6-5@691GHz CO3-2@346GHz

CO2-1@231GHz

13CO2-1@220GHz C18O2-1@220GHz

C17O3-2@337GHz

HD163296

dust settling

(Qi et al. 2011) CO snow line @ R~155AU

(Mathews et al. 2013)

[DCO+] /[HCO+]

=0.3

ALMA SV @band7, DCO+ 5-4

ALMA cycle 0

(Qi et al. 2013c)

CO snow line @ R~30AU

TW Hya Freeze-out of molecules on grains changes elemental

abundance in PPDs

Aikawa-san’s talk

Snow Lines & Planet Formation (e.g., Markwick+2002, Aikawa+ 2002, Bergin+ 2007, Dutrey+ 2014)

H2O snow line

(Oberg et al. 2011)

Ice

Gas

C-rich in Ice O-rich in Gas

O-rich in Ice C-rich in Gas

Snow Lines & Planet Formation (e.g., Markwick+2002, Aikawa+ 2002, Bergin+ 2007, Dutrey+ 2014)

H2O snow line

C-rich in Ice O-rich in Gas

O-rich in Ice C-rich in Gas

enhance C/O ratio

C-rich atmosphere

Comparison of C/O ratios in PPDs & exoplanetary atmospheres

constrains planet formation theory

・OH

S/N=250 AA Tau

Spitzer/IRS (R=600) Obs. of Water & Organic Molecules　

・H2O C2H2

HCN

CO2

Obs.

Model

(e.g., Carr & Najita 2008; Salyk+ 2008, 2011; Pontoppiddan+ 2010)

Infrared molecular lines could be tracer of C/O ratio distribution in PPDs

(JWST, TMT, SPICA, …)

(Carr & Najita 2011, Najita+ 2013)

HCN/H2O ⇔ Mdisk?

Trap of H2O in icy planetesimals?

Selsis 2007

Water & methane, etc. are found→ C/O ratios → constrain planet formation theory?

(Stevenson et al. 2010)

H2O, CH4, CO, CO2

(Marois et al. 2008, 2010)

HR8799 Keck

HR8799b Keck

Obs. of Exoplanetary Atmospheres

Keck

HR8799c

HR8799b

(Lee+ 2013, Barman+ 2011) (Konopacky+ 2013)

Transiting Short Period Jupiters, Neptunes & Super-Earths

Directly Imaged Gas Giants

Spitzer, GJ 436b

JWST, TMT, SPICA, …

(van

Dis

hoec

k et

al.

2014

)

DCN : TW Hya, LkCa 15 HD : TW Hya HDO, H2D+ : non-detection

Obs. of Deuterated Species in PPDs

(Bergin+ 2013) ~10-5 (Qi+ 2008, Oberg+ 2010, 2012) ~0.02

Deuterated Water

DCO+ : TW Hya, DM Tau, LkCa 15, HD163296 D/H~0.02-0.3 (van Dishoeck+ 2003, Guilloteau+ 2006, Oberg+2010, Mathews+ 2013)

(Guilloteau+ 2006, Chapillon+ 2011)

Comets

HD/H2

Rosetta Mission

＊Rosetta Mission

(Altwegg+2015)

Earth

ISM

Deuterated Water in Disks

(Fur

uya+

201

3, C

leav

es+

20

14)

H2O(ice)　→　O　→　 H2O(ice)

photodesorption ・dissociation @ disk surface

D fractionation : large small

adsorbed on grains

HDO

(Alb

erts

son,

Sem

inov

& H

enni

ng 2

014)

Deuterium fractionation is consistent with - Earth @ ~1AU - Comets @ ~10AU (2D mixing)

Deuterated Water in DisksGas

Ice

Laminar

2D mixing OCC Earth

HDO/H2O

Obs. of HDO will test the models!

§3 Formation of

Organic Molecules in Protoplanetary Disks

COMs Observations with ALMA

Glycolaldehyde around low mass

star forming regions

(Jorgensen et al. 2012)

(Belloche et al. 2014)

Iso-propyl cyanide around high mass

star forming regions in Galactic center

Complex Organic Molecules in Disks

→more complex mol. will be found by ALMA

c-C3H2 J=6-5 @ 218GHz HD163296, ALMA SV

(Qi et al. 2013b)

(Chapillon et al. 2012)

HC3N J=16-15, 12-11, 10-9 @ 146, 109, 91GHz MWC480, LkCa15, GO Tau, IRAM 30m, PdBI

CH3CN 140-130, 141-131,

@ 257GHz, MWC480,

ALMA cycle 2

(Oberg et al. 2015)

H2COH+  HOCO+  HCS+  

CH4  C2H2  HOC+  

HCNH+  

HNCCC  CH3  HCO+   OHCH2CH2OH  

HCCNC  C3S  C2S   CH3COCH3  

C8H-­‐  

CH2CN  C3O  C2O  

C2H5OH  CH2CHOH  HC3NH+  H2C3  C3N  CO2  CF+  

CH3OCH3  c-­‐C2H4O  H2C4  c-­‐C3H2  c-­‐C3H  C3  CO+  

CH3C5N  C6H  C5H  C4H  C3H  C2H  CH  

CH3C4H  

H2C6  

CH2CHCN  NH2CHO  NH2CN  HNCS  CH2  C2  

C2H5CN  CH2CHCHO  CH3CHO  CH3SH  CH2CO  HNCO  OCS  CN  

HC11N  CH3COOH  CH3NH2  CH3NC  CH2NH  H2CN  HCO  CO  

HC9N  CH3C3N  CH3CCH  CH3CN  HCOOH  H2CS  HNC  CS  

HC7N  HCOOCH3  HC5N  CH3OH  HC3N  H2CO  HCN  CH+

C6H-­‐  

C2H5OCHO  

by ~1975

C4H-­‐  

CH2OHCHO  

CH3CONH2  CN-­‐   C5N-­‐  

C3N-­‐  NH2CH2COOH?  → amino acids ?

Observed Interstellar Molecules

Amino acids in comet @ STARDUST

Amino acids in meteorites

⇔ relation with interstellar molecules ?

(Elsila et al. 2009)

after ~1997

1970 ~10 species

1980 ~50

→ 1995 ~100

→ 2015 ~180 species

→

Complex Molecule Fomration on Grain Surface

grain  surface

C,  O,  N,    S,  CO,  …  H  

\

desorpKon UV,  CR,  X-­‐rays

themal  

cold: < 20K warm: 30-50K

 Unsaturated  mol.  HCOOCH3,  NH2CHO,  …

NH2,    HCO,  … CH3O  

grain  surface

(e.g., Garrod+ 2006, 2008)

UV

migrate

CH4,  H2O,  NH3,    H2S,  CH3OH,  …

Saturated  mol.  

Complex molecules are formed on grains More complex molecules on warm grains

Modeling Complex Molecules in PPD

HCOOH

(Wal

sh, M

illar

, H

N 2

010)

z[AU

]

x[AU]

CH3OH

x[AU]

Grain  surface

C,  O,  N,    S,  CO,  …  H   H2O,  CH3OH,  …

Grain surface reactions

desorpKon UV  CR  

Xrays  

Photodesorption

Observing complex mol. & grain surface reactions

Prediction of CH3OH line fluxes (ALMA) H2CO line spectra

Flux

Den

sity

[Jy

]

Frequency [GHz] Frequency [GHz]

CH3OH line spectra

(Wal

sh, M

illar

, H

N e

t al

. 20

14)

ALMA band 3 4 6 7 8 9 10 3 4 6 7 8 9 10

H2CO line fluxes: consistent with observations CH3OH line fluxes: constrained by ALMA observations

Diagnosing grain surface reactions in PPDs

Complex Molecules on Warm Grains

Complex mol. are formed on warm grains at T~30-35K(~50AU) = cometary region

Z/R

R [AU]

Z/R

R [AU]

CH3OH

C2H5OH CH3COCH3 aceton

Tdust

30-50K

(Wal

sh, M

illar

, H

N e

t al

. 20

14)

OSU chemical network (Harada et al. 2010, Garrod et al. 2008)　

Comparison with Obs. tw. Comets

Complex molecules are formed on grains in disk Obs. toward comets are consistent with PPD model

Mol.  clouds(initial  condition)

(Wal

sh, M

illar

, H

N e

t al

. 20

14)

Model  (ice)(R>20AU)

Obs. from Comet

Disks in a Young Star Cluster

(Chen et al. 2005)

Trapezium cluster in Orion Nebula

Effect of irradiation from nearby massive star on chemical structure in disks?

H2

disk Ionization

front

photoevaporation UV

IonizaXon  front

Protoplanetary disk

HST

HST d=420pc

Most stars are formed in young star clusters ↓

Environmental effects in star clusters? (e.g., Lada & Lada 2003)

Isolated

gas-phase grain surface HCOOCH3

Dependence on Tinitial 30K 10K

Z/R

R [AU]

COMs : irradiated vs. isolated

R [AU]

Irradiated GFUV=106G0 (Walsh et al.2013, 2014a,b)

Tgas grain surface

Irradiated: some COMs are not formed efficiently

x 10

x 2

Irradiated

R [AU] R [AU]

Summary

Water, snow lines & organic molecules in protoplanetary disks

H2O snow line in PPDs will be detected using high-R spectroscopic observations

Comparison of C/O ratios in PPDs & exoplanetary atmospheres constrains planet formation theory

Obs. of deuterated molecules constrain disk model

Obs. of complex molecules in PPDs & comets constrain formation process of COMs in PPDs

Carbon Fractionation in Disks

(Woo

ds &

Will

acy

2009

)

-  Fractionation due to self-sheilding surface: 12C16O →  13CO →  C18O →  C17O →… :midplane

- Fractionation due to chemistry

ΔE=35K ΔE=9K

Fractionation may depend on temperature