The VLTI view of compact dusty environments around evolved stars Olivier CHESNEAU Observatoire de la Côte d’Azur (OCA) F. Lykou, E. Lagadec, A. Zijlstra (Univ. Manchester), S. Sacuto, P. De Laverny (OCA), O. De Marco (MNH), M. Matsuura (UCL), G. Clayton (Univ. Baton Rouge), B. Balick (Univ. Washington), N. Smith (Berkeley) To be or not to be a disc?

APN4 meeting, June 2007 The MIDI interferometric observations of compact dusty environnements 2 VLTI at ESO Paranal, Chile

APN4 meeting, 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;  m) 3-way beam combiner. Spectal resolution: R=30 (low resolution), 1500 (medium r.), (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, 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&A 12 arcsec HST 1 arcsec 0.1 arcsec

APN4 meeting, 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 observations VISIR 12.8  m [NeII]

APN4 meeting, June 2007 The MIDI interferometric observations of compact dusty environnements mas AU 500 AU 200AU α = 2.4 β = 1.03 h(100 UA)=17 UA Rin = 9 AU Density (2d disk) with α = 2.4 β = 1.03 h 100AU = 17 AU

APN4 meeting, June 2007 The MIDI interferometric observations of compact dusty environnements 7 See poster Foteini Lykou et al., #34

APN4 meeting, June 2007 The MIDI interferometric observations of compact dusty environnements 8 A silicate disc in the Butterfly nebula M2-9? B=40 m PA=107 ° To be continued…

APN4 meeting, June 2007 The MIDI interferometric observations of compact dusty environnements 9 OH : 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 (Matsuura, Chesneau et al. (2006))

APN4 meeting, June 2007 The MIDI interferometric observations of compact dusty environnements 10 Formation of OH Soker & Livio (2001) In the context of… M 2-9

APN4 meeting, June 2007 The MIDI interferometric observations of compact dusty environnements 11 The symbiotic system HM Sge: an ‘almost’ normal Mira WD MIRA 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 (2  10 5 K)

APN4 meeting, 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 T in =1600K T eff =3000K HWHM~8 mas at 8.5  m (~12AU), flattening 0.8, Major axis perpandicular to binary orientation HWHM~13 mas at 13.5  m (~22AU), flattening ~1 Sacuto, S., Chesneau, O., Vannier, M., et Crusalèbes, P. 2007, A&A, 465, 469

APN4 meeting, June 2007 The MIDI interferometric observations of compact dusty environnements 13  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, June 2007 The MIDI interferometric observations of compact dusty environnements 14 Summary CPD :CPD : 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)