1. High Resolution Mid-Infrared Imaging of Dusty Circumstellar Structure around Evolved Stars with the MMT Adaptive Optics System B.A. Biller, L.M. Close, A. Li, J.H. Bieging, W.F. Hoffmann, P.M. Hinz, D. Potter, D. Miller, G. Brusa, M. Lloyd-Hart, F. Wildi, and B.D. Oppenheimer, Steward Observatory

2. High Resolution Adaptive Optics Imaging in the Mid-Infrared MMT adaptive secondary removes ~8 warm optical elements compared to standard AO MMT adaptive secondary removes ~8 warm optical elements compared to standard AO Background 3x lower than standard AO opens up Mid-IR wavelengths to AO Background 3x lower than standard AO opens up Mid-IR wavelengths to AO Can achieve Strehls of ~100% at Mid-IR wavelengths and resolution down to the diffraction limit. Can achieve Strehls of ~100% at Mid-IR wavelengths and resolution down to the diffraction limit.

3. Lifecycle of Evolved Stars  AGB (Asymptotic Giant Branch) Significant ISM enrichment through Slow Wind Significant ISM enrichment through Slow Wind In some cases, dense toroidal structure can form In some cases, dense toroidal structure can form  Post-AGB / Proto-Planetary Nebula Mass loss ceases Mass loss ceases Circumstellar material observable primarily in IR Circumstellar material observable primarily in IR  White Dwarf / Planetary Nebula Hard photons from white dwarf ionize and light up Hard photons from white dwarf ionize and light up circumstellar material.

4. Planetary Nebulae Shapes Collimation due to:  Magnetic Fields  Dense Toroidal Structure  Binary Interaction  Not Well Understood Balick and Frank (2002)

5. RV Boo and CH Cyg RV Boo – AGB star with possible Keplerian disk RV Boo – AGB star with possible Keplerian disk CH Cyg -- Only known symbiotic triple star – consists of: CH Cyg -- Only known symbiotic triple star – consists of:  inner red giant/white dwarf pair (period~800 days, Hinkle et al. 1993)  outer red giant (period ~ 14.5 years, Skopal et al. 1996)  system viewed nearly edge on

6. A Keplerian Disk around RV Boo? Bergman et al. (2000)

7. RV Boo – Raw Data  Observations @ 9.8  m  SR ~ 100%!  145 Jy RV Boo total flux  5% eccentricity

8. Super-Resolution through Deconvolution 0.16” (60 AU @ 390 pc) FWHM disk, Position Angle of 120 o comparable to that of CO disk. 0.1”

9. Parallactic Angle vs. Position Angle

10. Modeling  Emission modeled using A. Li’s dust thermal emission models.  Grain size distribution modeled as a power law.  Minimum grain size: 0.01  m  Maximum grain size: 1000  m  Dust spatial distribution modeled as a modified power law.  Star modeled using Kurucz 3000 K M6IIIe star model.  Fit SED to our 9.8  m point and IRAS/ISO fluxes and spectra.  Best fit model had disk inclination o of 30 o to 40 o from edge on and a mid-IR disk mass of 1.6 x 10 -6 M sun

11. Model Comparison

12. CH Cyg Only known symbiotic triple star – consists of: Only known symbiotic triple star – consists of:  inner red giant/white dwarf pair (period~800 days, Hinkle et al. 1993)  outer red giant (period ~ 14.5 years, Skopal et al. 1996)  system viewed nearly edge on  Multiple outbursting phases since 1963

13. CH Cyg – Raw Images

14. CH Cyg – Cut Plots 9.8  m horizontal9.8  m vertical 11.7  m horizontal 11.7  m vertical

15. e vs. FWHM 9.8  m 11.7  m

16. Deconvolution – Highlighting the Spherically Symmetric Structure

17. CH Cyg – Modeling The Symmetric Structure

18. CH Cyg – Residual “Jets” Crocker et al. 2001

19. Conclusions RV Boo (Biller et al. 2005) -- 0.16” disk (60 AU at 390 pc) with PA of 120 o and inclined 30-45 o from edge on. RV Boo (Biller et al. 2005) -- 0.16” disk (60 AU at 390 pc) with PA of 120 o and inclined 30-45 o from edge on. CH Cyg (Biller et al. 2006) – Nearly spherically symmetric extension after deconvolution CH Cyg (Biller et al. 2006) – Nearly spherically symmetric extension after deconvolution  FWHM(9.8  m) of 0.15+0.01” (40.5+2.7 AU at 270 pc.)  FWHM(11.7  m) of 0.17+0.01” (45.9+2.7 AU at 270 pc.) Fainter, ~0.7” asymmetric extension stretching north to south, with similar direction/size to the radio/optical jets imaged by Crocker et al. 2001. Fainter, ~0.7” asymmetric extension stretching north to south, with similar direction/size to the radio/optical jets imaged by Crocker et al. 2001.

20. X Her and RS Cnc

21. Followup Observations