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IGRINS Science : Star Formation
: R = 40,000 ( ∆v ~ 7 km/s) at H & K-band
2011. 11. 15
여아란
The process of star formation
(Source: Spitzer Science Center:
http://ssc.spitzer.caltech.edu/documents/compendium/galsci/)
1. Constraining the Jet Models
: Jet/Outflows
: object  CTT
2. Constraining the Magnetospheric Accretion Models
: magnetic field intensity
: object  CTT, WTT
Constraining the Jet Models
1. Properties
2. The importance of Jet/Outflows (+ phenomenon)
3. Mechanism of Jet launching
- Models
- Observational Approach
4. Science with IGRINS
Outflows are ubiquitous
Blackhole outflow from Cantaurus A
young brown dwarf ISOOph 102 of 60 Jupiter
mass in Rho Ophiuchi
using the SMA (Ngoc et al.
2008)
A near IR image of the
massive YSO outflow in
IRAS 17527-2439 (Varricatt,
W. P., 2011)
1. Properties

Closely related with the accretion process
- Ṁwind/Ṁacc ~ 0.01
- no jet/outflows are discovered in WTTs
 Jet is well collimated (accretion, magnetic field, rotation)
(not general stellar thermal wind)
 Jet velocity ~100 – 300 km/s
(much lower than the escape velocity)
(Woitke et al. 2011)
(Hartigan et al. 1995)
2. The importance of Jet/Outflows

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
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Removing the angular momentum from the star-disk system
A fossil record of the mass loss
: mass-accretion history of forming stars
Features of outflow : dynamical environment of the engine
- S-shape
: outflow axis changed over time due to precession induced
by a companion
- C-shape
: motion of surrounding gas, or the motion of the
outflow source itself
Profound impact to their parent molecular clouds
shocks alter the chemical composition of the impacted media
1) Removing angular momentum of matter accreting
onto the forming star
The process of star formation
(Source: Spitzer Science Center:
http://ssc.spitzer.caltech.edu/documents/compendium
/galsci/)
HH 30
1995, 1998, 2000 : HST WFPC R-band
2) A fossil record of the mass loss
: the mass-accretion history of forming stars
Machine-gun-like blast of "bullets" of dense gas ejected from HH34
protostar at speeds of one-half million miles per hour, 1,500 light-years
away near the Orion Nebula. (HST image, J.Hester, Arizona State University,
1995)
3) Features of outflow : dynamical environment of the
engine
S-shape : outflow axis changed
ex) precession induced by a companion
C-shape : motion of surrounding gas, or
the motion of the outflow source itself
An image of HH 34 from various
telescopes and at various scales.
4) Profound impact to their parent molecular clouds
: dissipation, turbulence source (IMF)
5) shocks alter the chemical composition of the
impacted media
SiO abundance is enhanced in the shocks
: grain sputtering or grain-grain collisions releasing Si-bearing
material into the gas phase, which reacts rapidly with O-bearing
specise (O2 and OH) to form SiO
(Schilke et al. 1997, Caselli et al. 1997)
HH 211
(Lee et al. 2010)
3. Mechanism of Jet launching
1) Models
(1) X-wind : Disk Inner-edge
: magneto-centrifugal force
(e.g. Shang, Shu, & Glassgold 1998)
(2) Disk Wind : Broad range of disk radii
(e.g. Pesenti et al.2003)
(3) Re-Connection (Flare)
(e.g. Hayashi et al. 1996)
: magneto-centrifugal force
(1)
X-wind model
 X-wind is launching at the narrow
inner edge of the disk
 X-wind blow out with widely
opened angle.
 No mention about collimation of
the wind
 Ṁwind / Ṁacc ~ 0.01
Shu & Shang (1997)
Pyo 2009 여름학교 발표자료
(2) Disk-wind model
 Infalling mass pushes magnetic
field toward central star.
- If poloidal magnetic field
component has angle larger 30° from
vertical, centrifugal forces can
launch matter loaded wind along field
lines from disk surface.
-Wind transports away from 60 to
100% of disk angular momentum.
 Ṁwind / Ṁacc ~ 0.03
Pudriz & Norman (1983)
Pure disk wind model
Pyo 2009 여름학교 발표자료
(3) Reconnection-driven wind model
Montmerle et al. (2000)
Hayashi, Shibata, Matumoto(1996)
When dipolar stellar magnetic fields anchored to the inner part of an accretion
disk twist around because of the differential rotation between the star and the
disk and periodically reconnect to release the magnetic energy as hot plasma
The simulations of reconnection-driven winds naturally include the disk winds
Pyo 2009 여름학교 발표자료
2) Observational Approach
(1) X-wind model : Observational approach
Jet rotation ~ 0.5km/s at 10 AU (0.035”)
 Upper limit of launching radius
~ 0.014 AU (~3Rʘ) : X-wind model
~54 km/s at 0.014 AU (Keplerian rotation)
 VJ / Vd ~ 3
magneto-centrifugal force : X-wind
(Shu et al. 1995)
(Lee et al. 2009)
(2) Disk-wind + re-connection model
: Observational approach
Example 1)
FWHM 20-40AU at the projected distance of around 100AU
collimation is achieved on scales of a few tens of AU
 disk-wind model (Ṁwind / Ṁacc > 0.03)
(Garcia et al. 2001, Dougados et al. 2004)
Ray et al. 2007, PPV
Example 2)
[Fe II] Outflows
L1551 IRS 5
DG Tau
(Pyo et al. 2002)
(Pyo et al. 2003)
LVC : ~100km/s with ~100 km/s line width  disk-wind model
HVC : ~220 km/s with ~50 km/s line width  reconnection-driven model
The simulations of reconnection-driven winds naturally include the disk winds
Two different driving mechanisms working simultaneously
Outflow structure
(Pyo et al. 2003)
4. Science with IGRINS
Specification : R ~ 40,000  velocity resolution ~ 7 km/s
Object : Class II (Classical T Tauri stars)
 Disadvantage
: don’t expect a strong jets from relation Ṁwind / Ṁacc
 Advantage
- well known (or expect to be known) properties of the central star
and disk
: central star mass, disk mass, disk inclination ( jet inclination),
: magnetic field strength
: jet speed can be derived by a year observation
- Have a chance to see the very close region of the central star of
a few AU scale
: Jet rotation
 jet launch zone  constrain the Jet models
1) Studies in the optical region : Spectro-astrometic technique
a. Spatial and velocity distribution study in forbidden transition lines
[OI], [OII],[OIII],[NII],[SII]
 identify different velocity components, jet size, etc
b. Jet rotation study
: At 50-60AU from the source
and 20-30 AU from the axis rotation velocity
~ 5-25 km/s
 foot-point radii between 0.5 – 5 AU from the star
Velocity resolution ~ 55 km/s
Bally et al. 2007, PPV
Ray et al. 2007, PPV
2) Studies in the near-infrared region : Spectro-astrometry
 Jet rotation
1.644 μm [FeII]
IGRINS
θ = 0.16”, velocity resolution = 30 km/s
: not enough to study the Jet rotation
(Pyo et al. 2003)
Other science 1
Shock region studies (HH) : Spectroscopic observation
 kinematic studies : any turbulence ?
The 2 micron spectrum of HH 34 showing clear
H2 lines. From Gredel 1994
Other Science 2
Physical properties along the jet axis
HH 211
• [FeII] 1.533/[FeII]1.643 μm : probes densities up to 105 /cm3
• [FeII] 1.643/[SII] 1.03 μm, [FeII] 1.25/Paβ : estimate the fraction of iron
 cooling, chemistry, grain sputtering process in shocks
• [FeII] 1.643/[NI] 1.04 μm : ionization fraction
 jet mass flux
Constraining
the Magnetospheric Accretion Models
1. Property of CTT & WTTs
2. Model of the accretion process
: magnetospheric accretion model
3. Science with IGRINS
: measurement of the magnetic field strength
1. Property of CTT & WTT
: suspected the strong surface magnetic field
X-ray emission
Feigelson et al. 2006
2. Model of the accretion process
Magnetospheric accretion model ( & jet/outflows )
When the ram pressure of the accreting material and the magnetic
Pressure are equal, the motion of the accreting material will start to be
Controlled by the stellar field
The stellar magnetosphere prevents
the accretion disk from reaching the
stellar surface and the matter that
leaves the disk in its way to the star
must follow the magnetic field lines,
falling at high latitudes on to the star
(possibly for halting the migration of
young planets close to the stellar surface)
(Bouvier et al. 2007, PPV)
Three magnetospheric accretion models, analytically
 Can be tested by observation of magnetic field on CTTs
1
2
3
3. Science with IGRINS
 Measurement of the magnetic field
using Zeeman broadening ~ λ
In most atoms, there exist several electron configurations with the same energy, so
that transitions between these configurations and another correspond to a single
spectral line. The presence of a magnetic field breaks this degeneracy, since the
magnetic field interacts differently with electrons with different quantum numbers,
slightly modifying their energies.
Young stellar objects : consider the significant
doppler line broadening ~ λ
Step 1: measure the stellar properties in Optical band
(2.1m Otto struce telescope at the McDonald Observatory, R ~ 56,000)
: temperature, gravity, metallicity, rotational velocity
Johns-Krull et al. 2004
Step2: Near-infrared K-band : Ti I
 3m IRTF Cryogenic Near-IR Facility Spectrograph
 R ~ 37,300
Johns-Krull et al. 2004
Circumstellar disk science with IGRINS
: Chemistry in the inner disk (hot disk 1000 – 3000
Prof. Lee summarized it very well during
the IGRINS Summer school