The VLTI view of compact dusty environments around evolved

stars

Olivier CHESNEAUOlivier CHESNEAUObservatoire de la Côte d’Azur (OCA)Observatoire de la Côte d’Azur (OCA)

F. Lykou, E. Lagadec, A. Zijlstra (Univ. Manchester), S. Sacuto, P. De F. Lykou, E. Lagadec, A. Zijlstra (Univ. Manchester), S. Sacuto, P. De Laverny (OCA), O. De Marco (MNH), M. Matsuura (UCL), G. Clayton Laverny (OCA), O. De Marco (MNH), M. Matsuura (UCL), G. Clayton (Univ. Baton Rouge), B. Balick (Univ. Washington), N. Smith (Berkeley)(Univ. Baton Rouge), B. Balick (Univ. Washington), N. Smith (Berkeley)

To be or not to be a disc?

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 2

VLTI at ESO Paranal, Chile

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 3

VLTI Instruments

MIDI:

Mid-Infrared (8-13 m) 2-way beam combiner.

Spectral resolution R=30 (prism), R=230 (grism).

Spatial resolution: 5-20 mas

One visibility spectrum per observation, photometric spectrum, differential phase

(see Deroo et al. 2007)

AMBER:

Near-Infrared (J, H, K; 1-2.5 m) 3-way beam combiner.

Spectal resolution: R=30 (low resolution), 1500 (medium r.), 12000 (high r.).

Spatial resolution: 2-5 mas

Results: 3 visibility spectra, 3 differential phases and 1 closure phase spectrum per

obs, continuum corrected spectrum of the source.

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 4

CPD –56 seen at different spatial scales

10 m simulation

MIDI 8.7 m image

Chesneau, O., Collioud, A., De Marco O. et al., 2006, A&A12 arcsec

HST

1 arcsec

0.1 arcsec

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 5

An amorphous silicate disc in the Ant nebula, Mz 3

MIDI visibilities for different baselines orientations

HST observationsVISIR 12.8m [NeII]

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 6

140 mas - 100 AU

500 AU

200AU

α = 2.4β = 1.03 h(100 UA)=17 UA

Rin = 9 AU

Density (2d disk)

with

α = 2.4 β = 1.03 h100AU = 17 AU

2

)(2

1exp),(

rh

z

r

Rzr

α

o

R

zhrh o)(

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 7

See poster Foteini Lykou et al., #34See poster Foteini Lykou et al., #34

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 8

A silicate disc in the Butterfly nebula M2-9?

B=40 mPA=107 °

To be continued…

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 9

OH 231.8+3.4: not a disk but a highly distorted dusty shell

New observations (PI: E. Lagadec) with 4 new baselines just obtained

MIDI observations of the post-AGB star OH 231.8 (Matsuura, Chesneau et al. (2006))

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 10

Formation of OH 231.8 +3.4

Soker & Livio (2001)

In the context of…M 2-9

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 11

The symbiotic system HM Sge: an ‘almost’ normal Mira

WD

MIRAHM Sge : HM Sge :

Dusty symbiotic system (d~1.5 kpc), large separation 40mas~60 AU (Sources isolated with HST, Eyres et al. 2001)

Nova-like explosion (1975), unknown system before

Cold component: Mira (3000 K) + Hot component: White Dwarf (2105 K)

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 12

E0-G0(~75°)

U3-U4(~100°)

U2-U3(~45°)

N

E

MIDI Observations with UTs/ATs: 6 bases

Various DUSTY models from literature tested,Double shell models discarded (Schild et al. 2000, Bogdanov & Taranova 2001)

3.5mas

10 = 2.5

Tin=1600K

Teff=3000K

HWHM~8 mas at 8.5m (~12AU), flattening 0.8,

Major axis perpandicular to binary orientation

HWHM~13 mas at 13.5m (~22AU), flattening ~1

Sacuto, S., Chesneau, O., Vannier, M., et Crusalèbes, P. 2007, A&A, 465, 469

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 13

1 Gruis : 1 Gruis :

Nearby J star (153 pc)

A visual companion at large distance (G0V, 2.7’’- 400 AU)

A ‘disc’ (equatorial overdensity) and a fast (50km/s) outflow seen in millimetric observations (CO, Chiu et al. 2006)

Data indicate a spherical dusty wind + molecular atmosphere

Sacuto, S., Crusalèbes, P., Jorissen, A., Chesneau, O., Ohnaka, K 2007, A&A, submitted

APN4 meeting, 18-22 June 2007 The MIDI interferometric observations of compact dusty environnements 14

Summary• CPD-568302:CPD-568302: Inner disc resolved with MIDI (Chesneau et al. 2006) but large uv

coverage needed to precise the geometry

• OH231.8:OH231.8: the ‘polar’ size of dust emission measured (after Matsuura et al. 2006). There is a distorted, mildly flattened dusty structure, large uv coverage probably needed, complex geometry

• Mz-3:Mz-3: a 10-30mas (15-45 AU) disc is resolved with MIDI, a good disc model reached with amorphous silicate dust (see poster of F. Lykou, #34),

• M2-9:M2-9: MIDI observations under way, major axis > 45mas - 70 AU (larger than Mz3, crystalline silicates)

• HM Sge:HM Sge: the Mira wind only slighly affected by the WD (Sacuto et al. 2007a),

• Gruis:Gruis: A close J carbon star forming an extended equatorial overdensity (Sacuto et al. 2007b)

• Many other applications of MIDI/VLTI for evolved stars:

– Discs around post-AGB binaries (P. Deroo to come)

– Monitoring of novae outburst (RS Oph, V1280 Sco)

– Monitoring of the dusty clumpy environment of R CrBs (Leao et al. 2007),

– Studying the MOLsphere of evolved stars (Ohnaka et al. 2003, 2006, 2007)