chemical models of high mass young stellar objects great barriers in high mass star formation h....
TRANSCRIPT
![Page 1: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/1.jpg)
Chemical Models of High Mass Young Stellar
Objects
Great Barriers in High Mass Star Formation
H. Nomura1 and T.J. Millar2
1. Kyoto Univ. Japan, 2. Queen’s Univ. Belfast, UK
![Page 2: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/2.jpg)
§1 Introduction
![Page 3: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/3.jpg)
IHC SMA1
n
IRc6
CompactRidge
(Beuther et al. 2005, 2006)CH3OH CH3OCH3 SO2
13CH3CN
Orion KL, SMA
Mm/sub-mm Obs. of Mol. Lines
Unidentifiedlines
(Fallscheer et al. 2009)
IRDC18223-3, SMA
CH3OH
![Page 4: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/4.jpg)
AFGL 2591 by ISO
C2H2 5 HCN 2
(Knez et al. 2009)
Infrared Obs. of Molecular Lines
(Lahuis & van Dishoeck 2000)NGC7538IRS1 by IRTF/TEXES
Orion KL by ISO
(Lerate et al. 2006)
Small hydrogenated, saturated molecules
(Crockett et al. 2010)
Orion KL by Herschel/HIFI
![Page 5: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/5.jpg)
Origin of Abundant Molecules in HC
☆★
evaporation of icy mantles+ subsequent gas-phase
reactions abundant complex molecules
prestellar
star-formation
protostellar&outflow(shock
)
freeze out & grain surface reactions
evaporation of icy mantles
Young Stellar Evolution
X(M, hot core)~10-103 X(M, dark cloud)
M: NH3, H2S, CH3OH, (CH3)2O etc.
O H CO
SH2O
CH3OH
H2S
![Page 6: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/6.jpg)
Obs. of Icy Mantle Molecules
W33A by ISO
(Gibb et al. 2000)Hydrogenated, saturated molecules in ice
(e.g., Spitzer: Boogert+ 2008, Pontpiddan+ 2008, Oberg+ 2008, AKARI: Aikawa+ 2009)
Obs.
O H CO
N
O H2O
CO CH3OHN NH3
H
(Bottinelli et al. 2010)
CH3OH & NH3
Dust continuum
CO
(Caselli+ 1999, Tafalla+ 2004, …)
L1498 by IRAM
SVS 4-5 by Spitzer
![Page 7: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/7.jpg)
Grain surface chemistry(e
.g., W
ata
nabe &
Kouch
i 2008)
(Ch
arn
ley 1
997,
2001, 2005)grain surface
COH
...Amino acids?
Surface reactions in laboratory
High mass YSOs are good targets for test
![Page 8: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/8.jpg)
Hot Core Mol. in Various Objects
(Cazaux et al. 2003)
~500AU
CH3OH C2H3CN
(Kuan et al. 2004)
SMA
SMA
H2S
Starburst galaxies
(Minh et al. 2007)
(e.g., Martin et al. 2006, 2008)
NGC253
CMZ of Galactic Center(e.g., Requena-Torres+ 2008)Nearby extragalaxiesNGC253, NGC4945, M82, IC342, Marrei2, NGC6946
Grain surface chemistry seems universal
IRAS 16293-2422
IRAM
![Page 9: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/9.jpg)
§2 Hot Core
Chemistry
![Page 10: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/10.jpg)
Hot Core Chemistry – Cold & Hot
grain surface
C, O, N, S, CO, …H
Hydrogenated, saturated molecules
CH4, H2O, NH3, H2S, CH3OH, …
grain surface
(Charnley+ 1992, Millar+ 1997, …)
H2O H3O+ destroy molecules
NH3 HCN, HC3N, CH3CN, …
CH4, C2H2 carbon-chain mol.
H2S SO, SO2, …CH3OH CH3OCH3, HCOOCH3, …
Prestellar
ProtostellarGrain surface
T~10K Gas-phase reactionsT>100K
thermal evaporation from
grains
![Page 11: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/11.jpg)
Hot Core Chemistry – Warm
unsaturated moleculesCH3OCH3, HCOOCH3, …
Thermal history & UV photons in star forming cores?(Oberg et al. 2009)
CH3, HCO, … CH3O
grain surface
(e.g., Hasegawa+ 1992,Garrod+ 2006, 2008, …)
Surface reactions in laboratoryGrain surfaceT~40K
(Horn et al. 2004)
UV
CH3OH2++H2CO HCOOCH3 : inefficient
UV
![Page 12: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/12.jpg)
§3 Physical and
Chemical Models of High Mass
YSOs
![Page 13: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/13.jpg)
Physical & Chemical Models of YSOs
Line radiative transfer comparison with obs.⇔
Chemical reaction network +
radiative transfer T, hydrodynamics , vPhysical structure (Tdust, Tgas, gas, vgas)
gas-phase, grain surface, gas-grain interaction+ co
nst
rain
t
grain surface+ +
Get rid of activation
barrier of reactions ★
Tdust Tgas vgas
Transport molecules & dust grains
Thermal evaporation
Mobility on grains
UV
UV
![Page 14: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/14.jpg)
Chemical Structure of YSOs
Molecules are abundant at cloud center
CH3OH
H2CO
HCN
CH3CN
HCOOCH3
r [pc]
104yr
CH3OHH2CO
HCN
CH3CN
HCOOCH3
r [pc]
104yr
r★
(Nomura & Millar 2004)
Mantle mol.
H2O
H2O, CH3OHNH3, CO2
H2S, O2
H2O, CH3OH
NH3, CO2
H2S O2
Tdust
Tdust
![Page 15: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/15.jpg)
Effect of vinfall on low mass YSO chem.
(Aikawa+ 2008)
CH3OH CH3OCH3 : gas-phase chem > infallgas-phase chem ~104-5yr, infall ~103yr (~300AU/1km)
Warm grain surface reactions respond to formation of unsaturated molecules?
physical model radiative hydrodynamic simulation
Another pathway to unsaturated molecule formation?
t [yr] t [yr]
![Page 16: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/16.jpg)
Dependence on warm-up time
High mass: star<105yr Low mass: star>107yr
gas-phase reaction grain surface reaction
HCOOH formation(Garrod + 2008)
HCOOH (ice)HCOOH (gas)
Short(5x104yr)
t [yr]
T [K]
Abundances of unsaturated molecules in gas & ice
Grain surface chemistry & Stellar evolution time ?
HCOOH (ice)
HCOOH (gas)
Long(1x106yr)
t [yr]
T [K]
![Page 17: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/17.jpg)
UV,X-rays
Chemical Structure of Young Disks
inner diskH2O CH3OH
NH3 dust
near midplaneO H
CON dust
outer diskCN, C2H
HCN, H2CO, etc.
surface(e.g., Markwick+2002, Aikawa+ 2002, Bergin+ 2007)
COR<300AU
COR<10AU
(Walsh, Millar, HN 2010, in press)
Photo-dissociate
Frozen-out
accretion
Warm grain surface reactions during accretion?
![Page 18: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/18.jpg)
Chemical Structure of Young Disks
(Hein
zella
r, H
N,
Wals
h,
Mill
ar
20
10
, in
p
rep
.)
(Oka
moto
+ 2
009)
NH3, no motion(low mass star)
NH3, vertical motion(low mass star)
Photo-evaporation?
Transport of mol. from disk midplane to surface layer
Diagnose high mass disk chemistry & physics by ALMA
![Page 19: Chemical Models of High Mass Young Stellar Objects Great Barriers in High Mass Star Formation H. Nomura 1 and T.J. Millar 2 1.Kyoto Univ. Japan, 2. Queen’s](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649ebb5503460f94bc42e0/html5/thumbnails/19.jpg)
§4 Summary
Hot Core ChemistryGrain surface reactions + desorption from
grains+ gas-phase reactions
Grain surface chemistry seems universal
Physical & chemical models of high (& low) mass YSOs
Certain molecules are abundant near central star
Role of warm surface chemistry?Dependence on warm-up time
Stellar evolution, accretion velocity in disks
Diagnose physics & chemistry of YSOs by ALMA
__