Near infrared, IFU Near infrared, IFU spectroscopy of HH99spectroscopy of HH99

Teresa GianniniTeresa Gianninigiannini@oa-roma.inaf.itgiannini@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