Extinction and Dust Physics: Observation Focused

Extinction and Dust Physics: Observation Focused

Review of dust extinction from the ultraviolet to mid-infrared focusing on observations and what they tell us about the dust grains present in the interstellar medium. Presented at a weekly ISM*@ST group meeting.

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Karl Gordon

April 27, 2020
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  1. Dust Extinction & Physics Observation Focused Karl D. Gordon Astronomer

    STScI, Baltimore, MD ISM*@ST Group Meeting 27 Apr 2020 kgordon@stsci.edu @karllark2000 karllark@github Image: Messenger, Scott & Sandford, S. & Brownlee, D.. (2006). The Population of Starting Materials Available for Solar System Construction
  2. Outline • Continuum • Features – 2175 A / FUV

    Rise – Optical features – NIR features? – 3.4 HAC feature – 10 & 20 micron silicate features – Not considering DIBs, Ices
  3. 2175 A FUV Rise 3.4 μm NIR Features? Sil 10

    μm Sil 10 μm MIR Optical Features
  4. Continuum Extinction The Beginnings

  5. Optical/NIR Extinction - Graphite Cayrel & Schatzman (1954, AnAp, 17,

    555) Hoyle & Wickramasinghe (1962, MNRAS, 124, 417)
  6. None
  7. None
  8. None
  9. None
  10. Extinction Features Real Composition Constraints

  11. 2175 A - Graphite Stecher & Donn (1965, ApJ, 142,

    1681)
  12. 2175 A Properties Fitzpatrick & Massa (1986, ApJ, 307, 286)

  13. 2175 A “Pure” Absorption Feature Reflection Nebula IC 435 Calzetti,

    Bohlin, Gordon et al. (1995, 446, L97) albedo = Q sca /Q ext
  14. FUV rise Ultraviolet decomponsed

  15. FUV rise Wing of 2nd Graphite Feature Gordon et al.

    (2009, ApJ, 705, 1320)
  16. Optical Features (origin unknown) Massa, Fitzpatrick, Gordon, et al. 2020,

    ApJ, 891, 67 Centers: 4370, 4870, & 6300 A Widths: ~10% Two blue correlate w/ 2175 A
  17. Dorschner et al. 1995, A&A, 300, 503 Gordon et al.

    2000, ApJ, 544, 859 Olivine Silicates Fe Feature at ~1.5 micron? Emission spectrum from reflection nebula NGC 7023 NW filament
  18. 3.4 micron HAC Hydrogenated Amorphous Carbon (aliphatic bonds) Pendelton &

    Allamandola (2002, ApJS, 138, 75
  19. https://www.itrcweb.org/PetroleumVI-Guidance/Content/Appendix%20C.%20Chemistry%20of%20Petroleum.htm

  20. 10 & 20 micron Silicates Chiar & Tielens (2006, ApJ,

    637, 774)
  21. Crystalline Silicate Fraction ~0.2% (or zero) Kemper, Viernd, & Tielens

    (2004, ApJ, 609, 826) Amorphous Crystalline
  22. Grain Models Putting it together

  23. Relatively strong extinction at a range of wavelengths Extinction curves

    single parameter family (mostly) Cardelli, Clayton, & Mathis 1989, ApJ, 345, 245 Fitzpatrick, Massa, Gordon, et al. 2019, ApJ, 886, 108
  24. MRN Bare Grains Model Mathis, Rumpl, & Nordsieck (1977, ApJ,

    217, 425)
  25. Updated Bare Grain Model Weingartner & Draine (2003)

  26. Coated Grains Model Jones et al. (2013)

  27. None
  28. Chiar et al. (2013, ApJ, 770, 78)

  29. 2175 A FUV Rise 3.4 μm NIR Features? Sil 10

    μm Sil 10 μm MIR Optical Features
  30. Graphite Graphite Graphite? Fe Silicates? Silicates Silicates Graphite? Continuum: Carbonaceous

    and Silicate Grains HAC
  31. Backup

  32. None
  33. None
  34. None
  35. Stecher 1965, ApJ, 142, 1683

  36. Stecher 1966, ApJ, 157, 125

  37. Draine & Lee

  38. Dust Grain Modeling Gordon & Misselt (202x, in prep) Adding

    in dust scattering constraints possible (and lots of personal learning)