Time Variability

• We find that the number of HTCs varies as a function of time.
  
  
  • Really, its a function of angle between the Solar System's node and the Galactic center, .
  
  
• The peaks occur when two tides work together to bring perihelion distance down.
  
  
  • Disk tide: tides due to the Galactic plane; L_Z conserved.
    • For an orbit in ecliptic, strength is a function of argument of perihelion, .
    
    
  • Radial tide: tides due to the Galactic center.
    • For an orbit in ecliptic, strength is a function of and .
    
    
  • They work collaborate best when =20^O and 200^O.
    • This is where the peak starts.
    • The width of the peak is caused by the time it takes for objects to evolve onto HTC orbits.
  
  
• Disk tide ~10X stronger than radial tide.
  
  
  • But radial tide can change L_Z q_min
  
  
• Comet showers should occur every 120 Myr.
  
  
  • At peak there should be ~10X as many HTCs as currently observed.
  • For roughly half the time there should be no HTCs.