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Near infrared, IFU spectroscopy of HH99. Teresa Giannini [email protected]. INAF-Osservatorio Astronomico di Roma. Accretion and ejection of material from the protostar. Infalling Gas. Bipolar Outflow. Young Star. The star forming process. gravitational contraction. - PowerPoint PPT Presentation
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Near infrared, IFU Near infrared, IFU spectroscopy of HH99spectroscopy of HH99
Teresa GianniniTeresa [email protected]@oa-roma.inaf.it
INAF-OsservatorioINAF-Osservatorio Astronomico di Roma Astronomico di Roma
molecular coresmolecular cores
The star forming processgravitational gravitational contractioncontraction
t = 104 – 105 yr
accretion accretion discdisc
T Tauri starT Tauri star
t = 106 – 107 yrMain sequence Main sequence starstar
t > 107 yr
planetarplanetary systemy system
Bipolar OutflowInfalling Gas
Young Star
Accretion and ejection of material from the protostar
Protostellar Jets: observations
Properties:Size: 0.1 - 10 pcVelocity: 50 - 500 km s-1
Density: 102 - 106 cm-3
Temperature: 102 - 104 KMass loss: 10-5 - 10-8 M/yrIonization fraction: 0.02 – 0.5
HH111
visualinfrared
Jet Vjet Vs
Mach disc(reverse shock)
Bow shape forward shock
Bow head
Bow wing
HH34
Why is important to study bow-shocks? • direct interaction with the ISM:
compression, heating, medium acceleration
• irreversible chemical changes of gas composition (molecular dissociation, sublimation of ices, endothermic reactions, disruption of dust grains)
• accumulated thermal energy irradiated through line emission
ionic emission
H2
J-shock
ionic emission
C-shock
H2 emission
Near-Infrared lines
From line intensity ratios and profiles:
• Extinction• Temperature • Electron density• Ionization fraction• Velocity• Bow geometry
Ground electronic state
H2 ro-vibrational [FeII] fine structure
V=7
Davis et al.,1999
HH99: well known prototype of HH99: well known prototype of bow shock !bow shock !DD~130 pc (RCra star forming ~130 pc (RCra star forming region)region)
First 2-D analysis of a bow-shock: observing HH99 with SINFONI
1.7447 µm1.7449 µm1.7451 µm1.7453 µm1.7455 µm1.7457 µm1.7462 µm1.7464 µm1.7466 µm1.7468 µm1.7470 µm1.7472 µm1.7474 µm1.7476 µm1.7478 µm1.7480 µm1.7482 µm1.7484 µm1.7486 µm1.7488 µm1.7490 µm1.7492 µm
2-D structure of the shock surface IFU spectroscopy well suited
SINFONI spectrograph• Spatial resolution ~250 mas; FoV=8x8 arcsec2
• IFU spectroscopy in J, H, K• Spectral resolution: 2000 (J), 3000 (H), 4000 (K)
SINFONI data-cube
A: HA: H22 1-0 S(1) 2.12 1-0 S(1) 2.12 µmµm B: HB: H22 2-1 S(17) 1.76 2-1 S(17) 1.76 µmµm
H2 ro-vibrational transitions• Different morphology for low (E 30000 K) and high (E 30000 K ) excitation lines.
The intensity maps show a clear bow-shape morphology
C: [FeII] 1.64 C: [FeII] 1.64 µmµm D: [FeII] 1.75 D: [FeII] 1.75 µmµm E: H PaE: H Paß 1.28 µmß 1.28 µm F: [PII] 1.18 F: [PII] 1.18 µmµm
Atomic transitions
• Mainly [FeII] transitions (46 lines)• H, He recombination lines (8 and 2) and [PII], [CoII], [TiII] transitions• The atomic lines are emitted at the bow apex region
Giannini, Calzoletti et al. 2008
• More than 170 observed lines (normally few lines are observed)
H2 diagnostics: temperature map modelling the molecular emission
totJ
NQg
/kTE
,
Jv,Jv,eN
with: gv,J = (2I +1) (2J+1) N: Column density Q: Partition function
In the shocked gas the H2 ro-vibrational transitions are thermalized at the (kinetical) temperature T (LTE).
QNkTEgN totJvJv /ln/)/ln( ,,
• Temperature gradient from ~2000 K up to ~ 6000 K
• H2 emission ‘survives’ beyond the maximum temperature predicted by C-shocks (~3000 K)
• N(H2) strongly decreases toward the head (H2 dissociation)
103 K units
Fast non-dissociative C-type shock for the molecular emission (also at the bow-head)
ijij
jiij
cr T
A
n)(
H2 critical density values are very low (102-103 cm-3)
[FeII] at 1.644 µm
2 R di
s
• Rdis: cap radius beyond which H2 emission disappears : this happens at a certain point along the bow where vshock exceeds vdis, at which H2 dissociates.
From Rdis and D’ we measure Vdis = 70-90 km s-1
• D’ : projected distance between the intensity peak and the velocity peak
vdis important parameter that regulates :
• shock models
• efficiency of the H2 collisional
dissociation
• fractional abundance H/H2 and chemical
reactions in the post-shock gas.
H22 breakdown velocity • vdis is a function of the pre-shock density
• model predictions : vdis up to:
25 km s-1 (Kwan 1972) ;
50 km s-1 (Smith, 1996) ; 80 km s-1 (Le Bourlot, 2002)
Le Bourlot et al., 2002
Our result agrees with the maximum value of Le Bourlot model Models to be
revised?
From the line profile vb~ 115 km s-1
The 1.644 m peak is shifted with respect to the intensity peak: geometrical effect due to theinclination of the paraboloid : ~ 40-60
Gas-phase iron abundance modelling the atomic emission
Iron is normally locked onto dust grains: the observation of iron lines is a measure of the shock efficiency in disrupting dust grains and releasing metals in the gas phase.
18.1
26.1
][
][
PII
FeII
[FeII]1.257µm line contours
Comparison of the observed ratio:
refractory element
non-refractory element
with the solar abundance ratio
• P and Fe are assumed all single ionized• P and Fe lines lie nearby in wavelength, have similar excitation energy, critical density and first ionization potential
Iron fractional abundance map
• up to 70% of iron is in gas-phase (at the bow-head) . According to models this implies:• partial disruption of the dust grains
• vshock > 100 km s-1
• T 104 K
Dissociative J-type shock for the atomic emission at the bow head
Conclusions• First detailed analysis of the interaction region between a protostellar jet and the
ISM
• First multiline analysis detailed map parameters stringent observative constraints to shock models
• The classical “C-shock” (wings) plus “J-shock” (head) scenario is just a first order approximation :
- “hot” H2 also at the bow head (C-shock to be revised) - FeII also in the wings
new input for bi-dimensional shock models
• From kinematics new method to evaluate geometry and inclination angle
• First measurement of the H2 breakdown velocity new input for astrochemical models
Thanks!!
One-dimensional shock models: shock types
J(Jump)-type shock: discontinuity in the physical properties on a planar surface
J-shock with 200 yr magnetic precursor
J-shock with 900 yr magnetic precursor
C-shock
McCoey,2004
2
1
n
nns
kTnVV
• The ISM is permeated by magnetic field• Into the ISM ions and neutral are decoupled
2
1
22
22
1
nAi
iAiims VV
VVV
4 Ai
i
BV
If Vs > Vn and Vs < Vims
J-shock with Magnetic Precursor
As the Magnetic Precursor grows, the J discontinuity becomes fainter, up to disappear
J-shock
C(Continuous)-type shock
TMAX ~ 105 K
TMAX ~ 3-4·103 K
dsnAh
I iijij
ij
4
5.2/10 Aij
obsij II
5.2/)(
2
1
2
1 21
10 AA
obs
obs
I
I
I
I
First of all: the extinction maps !
Intensity of an optically thin transition i j:
Observed intensity:If the transitions are originated from the same upper level, the line ratio is independent from the local physical conditions, being a function only of atomic parameters (Aij and νij) and extinction.
H2 [FeII]
In the observed field of view variations of Av up to 4 mag are recognized
[FeII] diagnostics: electron density map
ne from line ratios between lines with:• different critical density• similar excitation energy
Nisini et al, 2002T = 2000KT = 15000K
103 cm-3 units
ne is typically 2-4 103 cm-3 with a peak up to 6 103 cm-3 at the bow head
Fast J-type shock for the atomic emission
• Highly excited [FeII] lines observed for the first time: electron temperature estimate at the bow head.
Te~18000 K
Te<10000 K
Bow kinematics and geometry
H2 at 2.122µm
Line profile compared with the instrumental profile
2
R dis
From the line profiles vshock~ 115 km s-1
[FeII] at 1.644 µm
The 1.644 m peak is shifted with respect to the intensity peak: geometrical effect due tothe inclination of the paraboloid : ~ 40-60
2 R di
s• Rdis: cap radius beyond which H2 emission disappears : this happens at a certain point along the bow where vshock exceeds vdis, at which H2 dissociates.
• D’ : projected distance between the intensity peak and the velocity peak From Rdis and D’ we measure Vdis = 70-90 km s-1
Diagnostics with [FeII] lines
Most of prominent observed transitions are originate from the 4D term and have similar excitation energies (~104 K)
They are NOT suitable to diagnose the gas temperature
They have different critical density (104105 cm-3)
The ratio of these lines is sensitive to gas density variation
The ratio with lines originated from the 4P term probes the electron temperature
A measure of the FWZI of a high resolution [FeII] line profile provides a direct estimate of the shock velocity (Hartigan,1987)
FWZI
ncr = 7.2 104 cm-3
Nisini,2002
Diagnostics with H2 lines
totJ
NQg
/kTE
,
Jv,Jv,eN
with: gv,J = (2I +1) (2J+1) N: Column density Q: Partition function
In the shocked gas the H2 ro-vibrational levels are thermalized at the (kinetical) temperature T (LTE)
QNkTEgN totJv /ln/)/ln( ,
Electronic ground state
NLTE
J-shock
C-shock
Constraining shock models with Boltzmann diagrams
A J-type component is responsible for the emissions from higher excitation levels (Flower,1999)
• A pure C-shock predicts temperature up to 3000 K• A pure J-shock predicts temperature up to 500 K
Temperature stratification
Departure from LTE (NLTE component):• Increase in Vs and n decreases the departure• Increase in B enhances the departure
Problema dei coefficienti di Einstein (A) delle transizioni [FeII]
Esistono 3 determinazioni teoriche (due di Quinet et al. 1996 e una di Nussbaumer & Storey 1988) che differiscono più del 30%, il che comporta: ~ 3 mag di differenza nel calcolo di AV, di conseguenza un fattore ~ 3 nella stima delle intensità di righe a 1 µm, un fattore ~ 34 nella stima delle intensità di righe a 0.5 µm !!!!
Per stimare i coefficienti di Einstein tramite osservazioni è necessaria una determinazione indipendente dell’estinzione, i.e. effettuata con rapporti di righe diverse dal [FeII]
Dalle righe di ricombinazione dell’idrogeno:AV=1.8+/-1.9 mag
Tale indeterminazione non permette una misura accurata dei coefficienti A
Le determinazioni teoriche di A non riproducono i dati sperimentali
Tale metodo dovrebbe essere applicato ad una sorgente di estinzione nota
One-dimensional Shock Models
Shock = discontinuity in the physical properties of a fluid
Shock Vs > cs in the InterStellar Medium (ISM): cs ~ 10 km/s
Rankine-Hugoniot Jump (J) Conditions for a strong (Vs >> cs), non-radiating (adiabatic) shock in a monatomic gas.
K2
1-s5
ps
s2
ps
ps
s2
ips
sps
ips
s km 100
V 101.4 T
V)16/3(P
V(3/4) P
(1/4)V V
4
Effects of magnetic field on a J-type shock
4
A B
V
Into the ISM ions and neutrals are decoupled
AVV
21
iAi
2
1
n
nn
kTnv
2
1
22
22
1
nAi
iAiims VV
VVv
Alfvén velocity
If B=0 and vs > vn
If B≠0 and vs > vn,ims
Discontinuous Shock (J-type shock)
If B ≠ 0 and vs < vims and vs > vn Magnetic Precursor
If B < Bcrit J-shock with Magnetic Precursor ((C+J)-type shock)If B > Bcrit C-type
shock (Draine, 1980)
Our result (vdis =80-90 km s-1)
marginally agrees with the
maximum value of Le Bourlot model,
but would imply a very low pre-
shock density
Models to be revised?
Le Bourlot et al., 2002
We measure vdis between 70 and 90 km s-1
H2 dissociation inefficient process