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.

Transcript

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)
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)
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
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)