astronomy 340 fall 2007 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Astronomy 340 Fall 2007 PowerPoint Presentation
Download Presentation
Astronomy 340 Fall 2007

Loading in 2 Seconds...

play fullscreen
1 / 27

Astronomy 340 Fall 2007 - PowerPoint PPT Presentation


  • 104 Views
  • Uploaded on

Astronomy 340 Fall 2007. 27 November 2007 Class #23. Research Experience for Undergraduates. 10-12 weeks over the summer $3500-$4000 in salary plus travel, housing Applications typically due in late Dec – early Feb Transcript Statement of purpose/interest Letters of recommendation

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Astronomy 340 Fall 2007' - eve


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
astronomy 340 fall 2007

Astronomy 340Fall 2007

27 November 2007

Class #23

research experience for undergraduates
Research Experience for Undergraduates
  • 10-12 weeks over the summer
  • $3500-$4000 in salary plus travel, housing
  • Applications typically due in late Dec – early Feb
    • Transcript
    • Statement of purpose/interest
    • Letters of recommendation
  • http://www.nsf.gov/crssprgm/reu/list_result.cfm?unitid=5045
review announcements
Review & Announcements
  • Titan
    • Describe Titan’s atmosphere and possible source of methane
  • Other Moons
    • Compare and contrast the properties of the 4 Galilean satellites
    • What are the salient features of Saturn’s moon Enceladus?
  • Rings
    • What’s the Roche limit? How is it significant?
    • Compare and contrast the ring systems of the gas giants
    • Size distribution? Composition? Dynamics?
pluto basics
Pluto - basics
  • Discovery
    • 1930 – Clyde Tombaugh (Lowell Obs)
    • Explain Neptune’s orbit?
  • Important Dates
    • 1976  CH4 ice, first estimate of diameter via albedo vs apparent brightness
    • 1978  6.4 day variation in brightness  discovery of Charon
pluto composition
Pluto Composition
  • Spectroscopy – CH4, N2, CO, H2O ices
  • Varied surface features
    • Compositional difference
    • Polar caps brighter
    • Darker equatorial  hydrocarbons?
  • Ice
    • Tenuous atmosphere from sublimation, but does it refreeze at 50 AU?
atmosphere
Atmosphere
  • Detection via occultation
    • Structure seen in “kinks” in ingress and egress  variation over the years (is Pluto’s atmosphere expanding?)
  • Composition  primarily N2
  • Pressure  few μbar
pluto s primary moon
Pluto’s Primary Moon

Charon

  • Discovered as appendage to Pluto
pluto s primary moon1
Pluto’s Primary Moon

Charon

  • Discovered as appendage to Pluto
  • Orbit  highly inclined
    • Orbital/rotation axis lie ecliptic
    • System seen edge-on twice in 248 year orbit
  • Size (via occultation)
    • Mass ratio = 0.12 (Moon/Earth ~ 0.01)
    • Dcharon = ~ 1200 km (Pluto ~2300 km)
giant impact origin canup 2005 science 307 546
Giant Impact Origin?Canup 2005 Science 307 546
  • Need to explain mass ratio/orbit
  • Collisions – similar to our moon
  • Numerical simulation show its possible!
    • Gravity
    • Compressional heating
    • Expansional cooling
    • Shock dissipation
    • 20000 – 120000 particles
    • Composition
      • Mg3Si2O5(OH)4
      • Various mixtures of water ice (40-50%) and rock
canup sph simulation including gravity heating cooling shock dissipation
Canup – SPH simulation including gravity, heating, cooling, shock dissipation
  • Ratio of impactor to total mass
  • Composition
  • Ratio of impact to escape velocity
  • Spin period
  • b’ = impact parameter
  • J = final angular momentum
pluto s moons
Pluto’s Moons
  • Charon
    • Semi-major axis = 19570 km
    • P = 6.3872 days
    • D = 1205 km
  • Nix
    • A = 48700 km
    • P = 25.5 days
    • D = 40 km
  • Hydra
    • A = 64800 km
    • P = 38.2 days
    • D = 160 km

Collisional origin?

What is the typical impact velocity of objects in the Kuiper Belt?

What is the escape velocity for impact ejecta in the Pluto system?

What implications can you draw from this?

new horizons http pluto jhuapl edu
New Horizons (http://pluto.jhuapl.edu)
  • Timeline
    • Jan 2006 – launch
    • Feb 2007 – jupiter encounter
    • Mar 2007 – June 2015 – “interplanetary cruise”
    • Jul 2015 – Pluto/Charon encounter
  • Science Objectives
    • Map surface composition of Pluto and Charon
    • Geology
    • Atmosphere – composition and escape rate
    • Surface temperatures
    • Similar studies of Kuiper Belt object
triton stern mckinnon 2000 aj 119 945
TritonStern & McKinnon 2000 AJ 119 945
  • Only large moon with retrograde orbit
  • Synchronously rotating (like our Moon)  has two distinct hemispheres
    • Leading side much more heavily cratered
  • High resurfacing rate (like Io, Europa)
    • Impact population from Kuiper belt
    • Lots of small impactors (< 1km)
    • Surface age ~ 100 Myr  volume resurface rate as high as Io, Europa
    • Geological/tectonic activity – possibly driven by tidal capture