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Stardust Review: Astrophysical Grains in Stellar Winds, the ISM, Debris Disks, and Comets

Stardust Review: Astrophysical Grains in Stellar Winds, the ISM, Debris Disks, and Comets. R. D. Gehrz Department of Astronomy, University of Minnesota. Outline. Stardust and stellar evolution Infrared spectra and the properties of stardust Stardust and nova winds

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Stardust Review: Astrophysical Grains in Stellar Winds, the ISM, Debris Disks, and Comets

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  1. Stardust Review: Astrophysical Grains in Stellar Winds, the ISM, Debris Disks, and Comets R. D. Gehrz Department of Astronomy, University of Minnesota R. D. Gehrz

  2. Outline • Stardust and stellar evolution • Infrared spectra and the properties of stardust • Stardust and nova winds • Grains in the ISM, debris disks and the Solar System • Conclusions • Appendix A: Gas Phase Abundances in Nova Ejecta R. D. Gehrz

  3. Stardust and Stellar Evolution R. D. Gehrz

  4. IR Spectra of Dust Grains: Molecular Structure • Silicates: SiO2 bond stretching and bending • vibrational mode emission at 10 m and 20 m • Silicon Carbide: SiC stretching vibrational mode • emission at 11.3 m • Carbon and iron: Smooth emissivity • Hydrocarbons (HAC and PAH): C-H stretch at 3.3 m and • other stretching modes at longer wavelengths R. D. Gehrz

  5. IR Spectra of Dust Grains: Mineralogy • Amorphous grains grow stochastically at low temperatures • and have featureless emission features • Crystalline grains are annealed at high temperatures and • their emission features have fine structure • The amorphous/crystalline transition occurs at ~1000K Amorphous Silicate F. J. Molster et al., A&A, 366, 923 (2001) C. Jäger et al., A&A, 408, 293 (2003) R. D. Gehrz

  6. IR Spectra of Amorphous and Crystalline Grains L. Piovan, R. Tantalo , & C. Chiosi, A&A,408, 559 (2003) R. D. Gehrz

  7. Silicates and SiC Grains in Stellar Winds Data from Gehrz et al. 1984, ApJ, 281, 303 R. D. Gehrz

  8. A Classical Nova Explosion: Accretion followed by a TNR R. D. Gehrz

  9. IR/Radio Development Phases • The luminosity of the outburst fireball is Lo LEdd • c measures nH and the ejected ionized gas mass Mgas during the free-free expansion phase • Lo LEdd = LIR for optically thick dust shells  Lo = constant for a long time Fireball Expansion Phase Free-Free Expansion Phase Coronal Phase in ONeMg Novae Dust Cocoon Phase in CO Novae  in m R. D. Gehrz (1988, 1990) R. D. Gehrz

  10. Dust Condensation in CO Novae Dust Formation in NQ Vul • Tc 1000 K • , where Vo is the • outflow velocity Visual Transition  Lo LEdd = LIR Tc = 1000K R. D. Gehrz (1988, 1990) R. D. Gehrz

  11. Nova Grain Properties Novae produce carbon, SiC, silicates, and hydrocarbons Abundances can be derived from visual opacity, IR opacity, and IR emission feature strength The grains grow to radii of 0.2-0.7m R. D. Gehrz

  12. Amorphous Carbon Grains and SiC in Novae Gehrz 1988, ARA&A, 26, 377 Iron seems not to be an option based on abundance arguments Gehrz et al. 1984, ApJ, 281, 303 R. D. Gehrz

  13. Grain Condensation in Nova QV Vul 1987 (2) • Carbon, Silicates, SiC, and PAH grains formed at different epochs • suggesting abundance gradients in the ejecta. • A. D. Scott (MNRAS, 313, 775-782 (2000)) has shown that this could • be explained by an asymmetric ejection due to a TNR on a rotating WD R. D. Gehrz

  14. Grain Condensation in V842 Cen (1986) • Amorphous Carbon • Hydrocarbons • Silicates From R. D. Gehrz, 1990, in Physics of Classical Novae, eds. A. Cassatella and R. Viotti, Springer-Verlag: Berlin, p. 138. R. D. Gehrz

  15. Carbon and SiC Grains in Nova 1370 Aql (1982) Data from Gehrz et al. 1984, ApJ, 281, 303 R. D. Gehrz

  16. Grain Condensation in V705 Cas (1993) • s Free-free, amorphous carbon, silicates, and hydrocarbon UIR emission are required to fit the IR spectrum in detail. There are many variables – constraining data are needed R. D. Gehrz

  17. Modeling the IR SED of V705 Cas (1993) There are many variables – constraining data are needed See C. Mason et al. 1998, ApJ, 494, 783 R. D. Gehrz

  18. Silicates in the Diffuse ISM Toward the GC J. E. Chiar et al., ApJ, 537, 749 (2000) R. D. Gehrz

  19. Silicates in Regions of Star Formation R. D. Gehrz

  20. Hydrocarbons in Regions of Star Formation (GMCs) 6 8 10 12 14  In m http://web99.arc.nasa.gov/~astrochm/UIR.html R. D. Gehrz

  21. Mineral Dust and Regions of Star Formation "8-13 Micron Maps of the Trapezium Region of the Orion Nebula," R.D. Gehrz, J.A. Hackwell and J.R. Smith, 1975, Ap.J. (Letters), 202, L33 R. D. Gehrz

  22. SOFIA and Comets: Mineral Grains What can SOFIA observations of comets tell us about the origin of the Solar System? ISO Data • Comet dust mineralogy: amorphous, crystalline, and organic constituents • Comparisons with IDPs and meteorites • Comparisons with Stardust • Only SOFIA can make these observations near perihelion Spitzer Data The vertical lines mark features of crystalline Mg-rich crystalline olivine (forsterite) R. D. Gehrz

  23. Comet Grain Properties R. D. Gehrz

  24. Comet Dust and Nova Dust Compared agr  0.7m agr  0.2m Comet Hale-Bopp r = 1.21 AU  TBB = 253K • Both Comet dust and nova dust contain silicates and carbon • Comets have coma emission dominated by grains the size of those produced in nova outflows R. D. Gehrz

  25. SOFIA and Comets: Protoplanetary Disks What can SOFIA observations of comets tell us about the origins of our Solar System and other solar systems? ISO Observations — Adapted from Crovisier et al. 1996, Science 275, 1904 and Malfait et al. 1998, A&A 332, 25 Image of Solar System IDP (Interplanetary Dust Particle) Disk System 50 microns ISO Data Solar System Comet • The silicate features in HD 100546 and C/1995 O1Hale-Bopp are well-matched, suggesting that the grains in the stellar disk system and the small grains released from the comet nucleus are similar R. D. Gehrz

  26. On the Nature of the Dust in the Debris Disk around HD 69830C. M. Lisse, C. A. Beichman, G. Bryden, and M. C. Wyatt The Astrophysical Journal, 658:584–592, 2007 March 20 Using a robust approach to determine the bulk average mineralogical composition of the dust, we show it to be substantially different from that found for comets 9P/Tempel 1 and C/ Hale-Bopp 1995 O1 or for the comet-dominated YSO HD 100546.Lacking in carbonaceous and ferrous materials but including small icy grains, the composition of the HD 69830 dust most closely resembles that of a disrupted P- or D-type asteroid. R. D. Gehrz

  27. Comet and Debris Disk Grains Compared R. D. Gehrz

  28. SOFIA and Extra-Solar Circumstellar Disks What can SOFIA tell us about circumstellar disks? 850 µm JCMT beam • SOFIA imaging and spectroscopy can resolve disks to trace the evolution of the spatial distribution of the gaseous, solid, and icy gas and grain constituents • SOFIA can shed light on the process of planet formation by studying the temporal evolution of debris disks 53 µm 88µm Debris disk around e Eridanae SOFIA beam sizes R. D. Gehrz

  29. Astrophysical Silicates in Different Environments • Silicates condensing in the winds of evolved oxygen-rich stars are • mainly amorphous silicates; Mg-rich crystalline silicates (forsterite • and enstatite) are abundant by up to 15% in massive outflows. • The diffuse ISM is dominated by amorphous silicates with an • upper limit to the crystalline/amorphous mass ratio of ~ 1%. • Silicates in molecular clouds are very similar to diffuse ISM • silicates; their absorption profiles peak at shorter wavelengths • and are characterized by absorption due to molecular ices. • Debris disks around some young stellar objects contain a high • abundance of Mg-rich crystalline silicates. • The crystalline/amorphous silicate ratio (CAR) is very large in comets • (as high as 4 in 9P/Tempel 1 during DEEP IMPACT) . R. D. Gehrz

  30. Conclusions about Astrophysical Grains The chemical composition and physical properties of grains in stellar winds, the ISM, debris disks, and comets have striking similarities (C, SiC, Silicates, hydrocarbons, a = 0.2 – 0.7 µm) Debris disks around young stars and comets have a high crystalline/amorphous silicate ratio (CAR) We infer that there was high temperature condensation or processing of grains in the early Solar Nebula The amorphous component (and possibly some of the crystalline component) of comet dust and IDPs may contain presolar grains that were formed in stellar winds and/or grown in GMCs R. D. Gehrz

  31. Appendix A: Gas Phase Abundances in Nova Ejecta R. D. Gehrz

  32. SOFIA and Classical Nova Explosions What can SOFIA tell us about gas phase abundances in Classical Nova Explosions? • Gas phase abundances of CNOMgNeAl • Contributions to ISM clouds and the primitive Solar System • Kinematics of the Ejection R. D. Gehrz

  33. Abundances from IR Forbidden Emission Lines Greenhouse et al. 1988, AJ, 95, 172 Gehrz et al. 1985, ApJ, 298, L47 Hayward et al. 1996, ApJ, 469, 854 R. D. Gehrz

  34. Abundance Anomalies in “Neon” Novae ONeMg TNR’s can produce and excavate isotopes ofCNO, Ne, Na, Mg, Al, Si, Ca, Ar, and S, etc. that are expelled in their ejecta ONeMg TNR’s are predicted to have highly enhanced22Naand 26Al abundances in their outflows. These isotopes are implicated in the production of the22Ne (Ne-E) and 26Mgabundance anomalies in Solar System meteoritic inclusions : 22Ne via: 22Na  22Ne + e + +  (1/2 = 2.7 yr) 26Mg via: 26Al  26Mg + e + +  (1/2 = 7105 yr) R. D. Gehrz

  35. Classical Novae and Abundance Anomalies • Novae process  0.3% of the ISM • (dM/dt)novae 7x10-3 M yr-1 • (dM/dt)supernovae 6x10-2 M yr-1 Gehrz, Truran, and Williams 1993 (PPIII, p. 75) and Gehrz, Truran, Williams, and Starrfield 1997 (PASP, 110, 3) have concluded that novae may affect ISM abundances: Novae may be important on a global Galactic scale if they produce isotopic abundances that are  10 times SN and  100 times Solar; Ejected Masses calculated from IR/Radio methods give a lower limit R. D. Gehrz

  36. Chemical Abundances in Classical Novae from IR Data (1) R. D. Gehrz

  37. Chemical Abundances in Classical Novae from IR Data (2) R. D. Gehrz

  38. Chemical Abundances in Classical Novae from IR Data (3) R. D. Gehrz

  39. Summary and Conclusions IR/Radio data yield quantitative estimates for physical parameters characterizing the nova outburst: D , Lo , Mgas , Tdust , adust , Mdust , Vo , Lo , grain composition, and elemental abundances Nova ejecta produce all known types of astrophysical grains: amorphous carbon, SiC, hydrocarbons, and silicates Classical Nova ejecta have large overabundances (factors of 10 to 100) of CNO, Ne, Mg, Al, S, Si R. D. Gehrz

  40. SOFIA and Classical Nova Explosions What can SOFIA tell us about the mineralogy of dust produced in Classical Nova Explosions? • Stardust formation, mineralogy, and abundances • SOFIA’s spectral resolution and wavelength coverage is required to study amorphous, crystalline, and hydrocarbon components • Contributions to ISM clouds and the Primitive Solar System QV Vul QV Vul R. D. Gehrz

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