Lecture 10 Cosmological Concepts ASTR 340 Fall 2006 Dennis Papadopoulos.
Astronomy 340 Fall 2007
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Transcript of Astronomy 340 Fall 2007
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ASTRONOMY 340FALL 200718 October 2007Class #14
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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
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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!
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Bernstein et al 2004
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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
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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
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Distribution of TNOs
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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?
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Classical KBOsMostly between42 and 48 AU
Formed via “quiet accretion”
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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
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Orbital Populations
Hahn & Mulhatra
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Scattered KBOs - orbitsTrujillo, Jewitt, Luu 2000 ApJ 529 L103
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Populations (Hahn & Malhotra 2005)
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Explanation for Colors? Neptune migrates from 25 AU to 40 AU Scatters objects Objects at 40 AU are relatively
unperturbed surfaces reflect methane ice
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KBO colors
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KBO Colors vs Dynamics
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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
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But are they really planets?