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Astronomy 340 Fall 2007

Astronomy 340 Fall 2007. 18 October 2007 Class # 14. Midterm Review Sheet. MIDTERM  OCT 25 in class No notes, books, friends You will get an equation and constants sheet Blue books or paper? Format: 2-3 somewhat quantitative questions, 2-3 qualitative questions

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Astronomy 340 Fall 2007

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  1. Astronomy 340Fall 2007 18 October 2007 Class #14

  2. Midterm Review Sheet • MIDTERM  OCT 25 in class • No notes, books, friends • You will get an equation and constants sheet • Blue books or paper? • Format: 2-3 somewhat quantitative questions, 2-3 qualitative questions • Exam will be based on lecture notes, book reading, HW assignments • There are a few hints in the review sheet

  3. A Little History • Gerard Kuiper and Kenneth Edgeworth “predicted” a distribution of small bodies in the outer solar system – 1940s • Real surveys began in early ’90s • 70,000 KBOs w/ d > 100 km (estimated) • 30 AU < a < 50 AU • Range of inclination/eccentricity • 1st KBO is really Pluto!

  4. Bernstein et al 2004

  5. Properties of TNOs • Green stars  scattered population • Red squares  classical KBOs • Lines are different power law fits • Surface density best fit by two power laws

  6. Basic Orbital Properties • “Classical” • Low eccentricity, low inclination • 40 AU < a < 47 AU • “Resonant” • Occupying various resonances with Neptune  3:2, 4:3, 2:1 etc • a ~ 40 AU • “Scattered” • High eccentricity, high inclination

  7. Distribution of TNOs

  8. Population • Total mass ~ 0.5 Earth masses • Total number  unknown • > 1500 detected via surveys • Colors (Tegler et al 2003 ApJ 599 L49) • ~100 KBOs with photometry • “classical” KBOs are “red” (B-R > 1.5) • “scattered” KBOs are “grey” • Largely colorless (flat spectrum) • Primordial?

  9. Classical KBOs Mostly between 42 and 48 AU Formed via “quiet accretion”

  10. Orbital Populations • Reflect dynamical history of the outer solar system • Hahn & Malhotra (2005 AJ 130 2392) • N-body simulation • Neptune migration  previously heated disk • Populates the 5:2 resonance with Neptune • “scattered” KBOs largely affected by planet migration

  11. Orbital Populations Hahn & Mulhatra

  12. Scattered KBOs - orbits Trujillo, Jewitt, Luu 2000 ApJ 529 L103

  13. Populations (Hahn & Malhotra 2005)

  14. Explanation for Colors? • Neptune migrates from 25 AU to 40 AU • Scatters objects • Objects at 40 AU are relatively unperturbed  surfaces reflect methane ice

  15. KBO colors

  16. KBO Colors vs Dynamics

  17. 2003 UB313 • 16 years worth of data • Orbital properties • a = 67.9 AU, e = 0.4378, i = 43.99 • Aphelion at 97.5 AU, perihelion at 38.2 AU

  18. But are they really planets?

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