The VLTI view of compact dusty environments around evolved stars

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The VLTI view of compact dusty environments
around evolved stars
To be or not to be a disc?

• Olivier CHESNEAU
• Observatoire de la Côte dAzur (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)

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VLTI at ESO Paranal, Chile
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VLTI Instruments
MIDI Mid-Infrared (8-13 mm) 2-way beam
combiner. Spectral resolution R30 (prism),
R230 (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 mm)
3-way beam combiner. Spectal resolution R30
(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.
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CPD 56 seen at different spatial scales
10 mm simulation
0.1 arcsec
MIDI 8.7 mm image
1 arcsec
12 arcsec HST
Chesneau, O., Collioud, A., De Marco O. et al.,
2006, AA
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An amorphous silicate disc in the Ant nebula, Mz 3
HST observations
MIDI visibilities for different baselines
orientations
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Density (2d disk)with a 2.4 ß 1.03
h100AU 17 AU
ß 1.03
h(100 UA)17 UA
a 2.4
Rin 9 AU
200AU
500 AU
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See poster Foteini Lykou et al., 34
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A silicate disc in the Butterfly nebula M2-9?
B40 m PA107
To be continued
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OH 231.83.4 not a disk but a highly distorted
dusty shell
MIDI observations of the post-AGB star OH 231.8
(Matsuura, Chesneau et al. (2006))
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Formation of OH 231.8 3.4
Soker Livio (2001) In the context ofM 2-9
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The symbiotic system HM Sge an almost normal
Mira

• HM Sge
• Dusty symbiotic system (d1.5 kpc), large
  separation 40mas60 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?105 K)

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MIDI Observations with UTs/ATs 6 bases Various
DUSTY models from literature tested, Double shell
models discarded (Schild et al. 2000, Bogdanov
Taranova 2001)
Sacuto, S., Chesneau, O., Vannier, M., et
Crusalèbes, P. 2007, AA, 465, 469
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• p1 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, AA, submitted
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Summary

• CPD-568302 Inner disc resolved with MIDI
  (Chesneau et al. 2006) but large uv coverage
  needed to precise the geometry
• 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 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 MIDI observations under way, major axis gt
  45mas - 70 AU (larger than Mz3, crystalline
  silicates)
• HM Sge the Mira wind only slighly affected by
  the WD (Sacuto et al. 2007a),
• p1 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)