Lect3 Comet Dust (11-03-09)

Lect3 Comet Dust (11-03-09) - Comet Dust (11-4-09)...

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Comet Dust (11-4-09)
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Assignment for next week: Chapter “Evolution of Comets into Asteroids” by Weissman et al. pdf file: part 5.ch7 in Asteroids III (Except for Section 4) Remember: Third Exam Thu 11-19-09 Graduate Students: Term paper due at start of class Tue Dec. 1 HARDCOPY
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Outline of Comet Dust I. Main Characteristics of comet Dust II. Main Characteristics of IDPs III. Origin of Crystalline Silicates in Comets Helpful reading : Pages 578 and 579 (Section 3.3) of paper by Campins et al. 2004 (pdf in website)
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I. Main Characteristics of Comet Dust A. Before comet Halley, only three solid State Spectral Features: 3 μ m water ice (absorption) 8-13 μ m silicates (emission) 20 μ m silicates (emission) B. Since Halley 1) Remote sensing: - Spectral structure in 8-13 μ m => crystalline silicates , including olivine - 3.4 μ m emission: C-H stretch of organic molecules , including CH 3 OH (Methanol) 1) In Situ:
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I. Main Characteristics of Comet Dust A. Since Halley 1) In Situ: - Elemental composition of comet Halley’s dust is close to chondritic (CI) or cosmic (Sun) abundances, with H, O, C, N and S more abundant in comets than in CI meteorites, i.e., comets are more primitive than CI meteorites - Discovery of CHON particles (about ½ of comet dust) - Two end members of dust: silicates and CHON , possibly silicate cores and CHON mantles - “Missing” carbon from gas phase found in CHON dust - Mineralogy of silicates in comet Halley resembles that in anhydrous (chondritic porous) Interplanetary Dust Particles (IDPs), i.e., these IDP are likely from comets
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Outline of Comet Dust (cont) I. Main Characteristics of Comet Dust A. Specific examples: Comets Hale-Bopp and 9P/Tempel 1. Hale-Bopp (Oort Cloud) 2. 9P/Tempel (Jupiter-family, i.e. Kuiper Belt) Observed bands and detected species Differences among and between JFC and OC comets
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I.C Comets Hale-Bopp and 9P/Tempel ISO spectrum of Comet Hale-Bopp
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Spitzer Spectra of 9P/Tempel before and after impact After Before
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Observed spectral bands and detected species I.C Comets Hale-Bopp and 9P/Tempel
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Composition of dust in comet 9P/Tempel after spacecraft impact
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Detected species Differences among and between JFC and OC comets I.C Comets Hale-Bopp and 9P/Tempel
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Comparison of 9P/Tempel with Hale-Bopp Differences among and between JFC and OC comets
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Some cases of compositional differences are clear: Contrast between comets with Mg-rich crystals (e.g., Hale-Bopp), and comets with Fe-rich crystals (9P/Tempel) Primordial or evolutionary difference? Indicative of degree of hydration in the nebular region where they formed?
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This note was uploaded on 11/09/2009 for the course AST 4142 taught by Professor Campins during the Fall '09 term at University of Central Florida.

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Lect3 Comet Dust (11-03-09) - Comet Dust (11-4-09)...

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