The Mira Imaging Project: Near IR, VLBA, and ThermalIR

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The Mira Imaging ProjectNear IR, VLBA, and
Thermal-IR

• Wesley A. Traub
• Harvard-Smithsonian Center for Astrophysics
• AAVSO Symposium Mira Companions Planets
• 26 April 2004
• Cambridge, Mass.

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Part 1. The Mira Imaging Project 15 People and
3 Interferometers

• CfA Sam Ragland, Wes Traub, Marc Lacasse, Peter
  Schuller
• GSFC Bill Danchi, Jayadev Rajagopal, Debra
  Wallace
• Grenoble JP Berger
• JPL/MSC Rafael Millan-Gabet
• NRAO Bill Cotton
• UC Berkeley Charles Townes
• U. Iowa Lee Anne Willson
• U. Mass Pete Schloerb
• U. Mich John Monnier, Ettore Pedretti

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The IOTA Interferometer
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The ISI Interferometer
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The VLBA Interferometer
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Part 2. Miras are Wet
Stratoscope II observations by Woolf,
Schwarzschild Rose (1964) suggested that Miras
had water in their spectra. However the idea was
not taken seriously. ISO observations by Tsuji,
Ohnaka, Aoki Yamamura (1997), Yamamura, deJong
Cami (1999), and by Tsuji (2000), found strong
water bands in the infrared. IOTA and ISI
observations by Perrin etal (1998-2004),
Schuller etal (2004), Mennesson etal (2002),
Chagnon etal (2002), and by Weiner, Hale,
Townes (2003) suggested a connection between the
strange diameters and water or dust shells. Here
we show the connection explicitly.
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HR Diagram for AGB Stars
Ref. Kaler, Extreme Stars, p.52.
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Ascending the Giant Branch for the 2nd Time
(i.e., the AGB)
Ref. Kaler, Extreme Stars, p.56.
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SiO Masers around Mira
Ref. Cotton et al., AA 414, pp. 275-288, 2004.
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SiO Masers around R Leo
Ref. Cotton et al., AA 414, pp. 275-288, 2004.
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Star lt Water Shell lt SiO Shell
Ref. Cotton et al., AA 414, pp. 275-288, 2004.
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IOTA 3 Telescopes
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2-Beam Interference Fringes
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JHK spectrum K sub-bands
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Mira Shell Model
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R Leo Visibility K-Band
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R Leo Visibility K sub-bands
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Mira Visibility K sub-bands
Ref. Perrin et al., submitted to AA, 2004.
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Khi Cyg Visbility K sub-bands
Ref. Perrin et al., submitted to AA, 2004.
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Smaller Star --gt Fundamental Mode Oscillation
Ref. Perrin et al., submitted to AA, 2004.
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R(shell) 2R(star)
Ref. Perrin et al., submitted to AA, 2004.
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IOTA shell ISI shell
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IOTA shell lt SiO shell
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Water Spectrum at 2000K
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Water at 2000K, Smoothed
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Measured Water Optical Depth
1022 cm-2
1021 cm-2
1020 cm-2
1019 cm-2
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Model of Water Column Density
If we assume dM/dt 1x10-6 sun/year and RAU
2.6 AU, and Tyr 1 year, and O/H 1 wrt
cosmic, then N(H2O) 7x1019 cm-2. We measure
N(H2O) 3x1021 cm-2, which is 40 times
larger. This suggests we need to enrich O/H by
about 40 times cosmic.
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Part 3. Miras are Lumpy
Schwarzschild originally suggested that giant
stars might have very large spots, but this has
not yet been confirmed. Karovska (1997) used HST
to image Mira, and found it to be elongated by
about 30. We now plan to use IOTA and ISI to
image AGB stars at wavelengths where the
surrounding material is transparent as well as
where it is relatively opaque, and thereby learn
the source of the lumps.
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HST Image of Mira
Mira B A original
deconvolved
Mira A enlarged
Ref. Karovska, ApJ 482, pp. L175-L178, 1997.
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IOTA 3 Telescopes --gt Phase Closure
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Image of Capella (IOTA)
This image of the Capella binary was made at IOTA
with the 3-telescope configuration, in H-band.
Ref. Stefan Kraus (MS Thesis, U.Mass., and Pete
Schloerb, 2003
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Image of lambda Vir (IOTA)
Ref. Monnier et al, accepted by ApJ, 2004.
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AGB Closure Phase (IOTA H-band)
Ref. Ragland et al., preprint, 2004.
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R Cnc Closure Phase (IOTA H-band)
Ref. Ragland, 2003.
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Mira Closure Phase (ISI N-band)
Ref. C. Townes and J. Weiner, 2004.
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Fringes from 3 Telescopes
Ref. Ragland 2003
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H-band Spectral Region
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The Mira Imaging Project The Next Few Years
We have a pending NSF grant to carry out the Mira
Imaging Project over the coming 3 years. We
plan to image 11 Miras 3 carbon stars at IOTA,
ISI, VLBA. We expect to make connections
between these results, and pin down the physical
mechanisms of the huge non-symmetries in these
stars, as they develop.