Chemical Processes in Protoplanetary Disks ~ Water, Snowlines & Organic Molecules ~ DTA Symposium June 1-4, 2015 @ NAOJ Hideko Nomura (TITECH)
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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
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