planets

• Good

  • we have found a plethora of nearby planets

• Bad

  • They are totally unlike our solar system
    • masses typically 1 Jupiter but
    • orbits typically < 1 AU
  • The standard model for planet formation has gas giants (Jupiter) forming at and beyond ~ 5 AU
    • “ice zone”, place where very abundant ices can freeze
      • vigorous formation of planitesimals
    • where temperatures cold enough to retain H and He
      • recall escape velocity, and thermal velocity of atoms

• Upsilon Andromeda has 3 planets circling it

  • from Doppler velocities
• Hipparchos satellite detected the star’s wobble (news)
  • implies outer planet (2.5 AU, d) is actually 10 MJupiter

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