Formations of Planetary Systems Test 1

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  1. What is so special about the Solar System?
    • - Sun has no companion
    • - Planets are non-resonate (resonance observed in other star systems)
    • - Packed (no space to add extra planets)
  2. Properties of the Solar System
    • Sun:
    • - typical mass, typical metal content (not H/He)
    • - mass dominates solar system
    • - heavy elements mostly in sun
    • - no companion

    • Gas Giants:
    • - mostly H/He
    • - not solar composition
    • - more heavy elements than sun

    • Resonance
    • - planets not resonate
    • Image Upload
    • where i, j are integers

    • Packed
    • - between planets, bodies exist where orbits are stable
    • - no room to add extra planets

    • Asteroid Belt
    • - Kirkwood Gaps (resonance with Jupiter)
  3. Angular Momentum
    Image Upload

    Image Upload


    Image Upload


    Dominated by planets
  4. Minimum Mass Solar Nebula Procedure
    Estimates minimum gas needed to form planets

    1.) Estimate heavy elements (Fe) to get mass

    2.) Calculate area of disk (annulus extending halfway to neighboring planets)

    3.) Image Upload
  5. MMSN Standard Form
    Image Upload


    Image Upload

    where Image Upload


    • - Most of the mass is in outer disk
    • - different Image Upload for each planet
  6. Detection Techniques
    • - Doppler shifts
    • - Transits
    • - Microlensing
    • - Direct imaging
    • - Astrometry
    • - Pulsar timing
  7. Direct Imaging
    • - gives info about composition
    • - resolve light from planet as separate source (fraction of starlight reflected by planet)

    Image Upload

    -gives planet's brightness (very faint compared to star)

    • Separating Planet from from Star:
    • - dust, atmosphere, telescope size, diffraction = limitations
    • - Diffraction Limit: Image Upload D = diam of tele

    - light that planet absorbs is re-radiated as Thermal radiation (T~300K for Earth)
  8. Transits
    - drop in stellar flux is observed Image Upload

    • - look for periodic dips due to planet transits (f = 0.01 for J-like planets)(f = 1-0.99)
    • - on ground, precision sufficient to find gas giants, but atmosphere prevents detection of terrestrial planets

    • Probability of Observation:
    • Image Upload

    - lower a = higher P (good way to find planets close to star)

    • Observables:
    • - Depth of Transit Image Upload

    - Period of Orbit Image Upload

    - Stellar Parameters (a, Image Upload)
  9. Radial Velocity (Doppler Shifts)
    • - star orbits center of mass (moves b/c of planet)
    • - detect line of sight (radial) variation in stellar velocity to reflex motion
    • - high precision spectra -> measure v via dopp. effect

    • Conservation of Momentum: Image Upload
    • Orbital Speed of Star: Image Upload

    • For an observer at inclination i:
    • Image Upload
    • - k=amplitude
    • - gives lower limit for Image Upload

    • Observables:
    • 1.) Period -> a, knowing Image Upload
    • 2.) k -> Image Upload = minimum mass of planet
    • 3.) eccentricity from shape of time dep (skewed sine curve = e > 0)
    • 4.) when i~Image Upload, get true mass
  10. Protoplanetary Disks
    • - stars form in molecular cloud cores
    •      - most gas in solar system not molecular
    •      - Scale: r~0.1 pc, M~M(sun) - a few M(sun)

    • - Collapse time: Image Upload (depends only on Image Upload of cloud)(typically 3 - 5 Myr)
    • - Specific Angular Momentum of Disk:
    • Image Upload
    • for a disk with scale Image Upload and rotation speed Image Upload:
    • Image Upload
    • Specific L at distance r from a protostar of mass Image Upload:
    • Image Upload
    • - Characteristic Disk Size: Image Upload
    •      - even a very small rot. vel. on cloud core = gas formation
    •      - disk MUCH bigger than star (unless binary)
    •      - Binary: L of cloud core lost in L of orbiting binary
    •      - B-fields slow down rot. as cloud collapses = nonexistent/small cloud

    • - Once star and disk form: Image Upload
    •      - implies:
    •      - L transport within disk
    •      - OR L loss (wind)
    •      - low loss = disks stable for Image Upload (outlive collapse)
  11. Star Formation
    • - Class O:
    •      - collapse and formation of protostar
    •      - protostar shrouded by surrounding dust

    • - Class I:
    •      - star and disk have formed (possibly jet)
    •      - continued in-fall (cloud & core still accreting)

    • - Class II:
    •      - star and disk only

    • - Class III:
    •      - disk has dispersed
    •      - pre-main-sequence star
    •      - weak-lined T-Tauri star

    • - Disk Lifetime:
    • 1.) Measure disk fraction in young stars
    • 2.) Date stars in clusters
    •      - usually Image Upload

    • - less than 10 Myr to form gas giants
    • - final formation of terrestrial planets must have occured in a gas-free environment
Author:
DrGirlfriend
ID:
238907
Card Set:
Formations of Planetary Systems Test 1
Updated:
2013-10-06 18:14:45
Tags:
Astronomy Planetary Systems
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Description:
Formations and Dynamics of Planetary Systems Test 1
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