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1
Mikako MatsuuraNAOJ
Dusty disks in evolved stars?
Post-AGB (Asymptotic Giant Branch) starsPlanetary Nebulae (PNe)
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Main sequence
Red giant branch (RGB)
AGB
Post-AGB
Planetary nebula
Luminosity [Lsun]
Effective Temperature [K]
The evolutionary tracks of 1, 5 and 25 Msun stars on the HR diagram (Iben 1995)
What arepost-AGB stars,
planetary nebulae (PNe)?
Late stage of stellar evolution for low mass stars (1-8 Msun in main sequence)
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Some examples of unique shapes and
common-namesNGC 6537Spider Nebula
NGC 2392Eskimo Nebula
OH 231.8+4.2Rotten Egg Nebula
NGC 6542Cat’s Eye Nebula
4
Current problems in the field of PNe research
Change in shapes
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ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB
Main Sequence
(MS)AGB stars
Planetary nebulae
(PNe)
1-8 Msun Central star: ~0.6 Msun
Mass loss
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Post-AGB stars and PNe
Post-AGB stars and PNeAsymmetric structureRoundEllipseBipolar
AGB stars : spherical symmetry
Balick & Frank (2002)
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Formation mechanisms of bipolar outflows
Circum(-binary) diskRemnant of AGB mass loss
Magnetic field
Troidal shaped AGB wind
Magnetic field
Balick & Frank (2002)
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Disk model
Hydrodynamic model by Icke (2003)
A warped disk
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Two casesNGC 6302 (Bug Nebula)OH 231.8+4.8 (Rotten Egg Nebula)
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Butterfly nebulaIcke’s model resemble to the shape of NGC 6302
About 8 arcsec disk?
Icke’s model Matsuura et al. (2005)
NGC 6302HST optical image
(H, NeII composite)
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Dense disc
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ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB
Optical three band composite image (HST)
Matsuura et al. (2005)
Extinction map A(H) [mag]H - 6cm
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JCMT 450 m image
Central core
Bipolar
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ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB
Lo
g I [Jy p
er beam
]
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Source of 450 m flux
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ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB
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ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB
5 arcsec
6 cm image(free-free emission)
20 arcsec
CoreI450m=3Jy per beamI450m(ff)~0.4Jy per beam-> 450m dust excess
LobeI450m~1Jy per beamI450m(ff)<0.1Jy per beam
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Results for NGC 6302 study
A warped discExpanding discFormation mechanism of the disc
Circum(-binary) disc. Binary? Too large inner radius?
Magnetic field can form the bipolar, however, the presence of the disc is not necessary
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Compact disks
Icke’s model’s Too large disk compared with the size of outflow
In most of the case, disk is more compact, especially at early phase of post-AGB
HST Optical image of the post-AGB star, OH 231.8+4.2
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The post-AGB star, OH 231.8+4.2
HST optical imageRed: 791nm (cont.)
Green: 675 nm (cont.+ionise lines)
Blue: combination of Ha (656nm) and NeII (658nm)
Collimated outflow Shocked bubble Dense torus
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Infrared images of OH 231
Bujarrabal et al. (2002)
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Infrared images of OH 231
InfraredIonized linesLess dust extinction
Central region is more apparent
Very compact and bright object at the centre
Matsuura et al. ApJL accepted
ESO/VLT/NACO
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Infrared images of OH 231
11.7 micronJura et al. (2002)
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Very compact disk
Jura et al. (2002)’s fitting to SED
Compact diskThe emission from blackbody at 130 K from a cylinder of radius 5x1015 cm at a tilt angle of 54 degrees
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MIDI VLTI observations
MID-infrared Interferometric instrument (MIDI)
UT3 - UT4 62.4 metre baseline
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MIDI VLT observations
Observing logSmall angular informationVariation in projected length
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Spectra from MIDI
Spectra from MIDI
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ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB
Wavelength [micron]
Flu
x [J
y]
8 1310
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Visibilities (correlated flux)
00 .511 .52891 0111 21 3O B 1 (6 1 .7 m )O B 2 (5 8 .9 m )O B 3 (5 2 .8 m )O B 4 (4 7 .4 m )W a v e le n g th [m ic ro n ]
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Radius of the disk
Distance 1.3 kpc, member of open cluster M46 (Jura & Morris 1985)
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Model fit (preliminary)
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Comparison with other observations
MIDI : 40-50 AUSiO : 3 AU
MIDICircumstellar material (probably disk)
Not the central star
R(star) ~ 3 AUSanchez Contreras et al. (2002)
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Binary disk model
Binary with a separation of 10-100 AU
Binary disk may be formed
Mastrodemos & Morris (1999)
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Conclusion & Future work
Circumstellar material with a radius of 40-50 AU (upper limit)
Very compact: binary disk?
Future: measurements of visibilities in different uv-plane
29
Model for far-infrared excess
Dust ~0.03Msun
Tdust<100K
1x1016cm < Rdust < 10x1016cm