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Transcript of Www.astro.washington.edu/observatory/ Extra-Solar Planets Theodore Jacobson Observatory University...
www.astro.washington.edu/observatory/
Extra-Solar Planets
Theodore Jacobson Observatory
University of Washington
Brian Stephanik
October 5th, 2005
Topics for tonight
What are (extra-solar) planets?Very brief historyDetectionThe presentThe future
Where do planets fit in?
Asteroids, planets, and stars: where to draw the line? Rocky core – gaseous atmosphere – nuclear fusion On-going debate: Pluto
History
A very new science– Last 15 years
1989 – Mention of (possible) extra-solar planets in a research paper
1993 – Confirmed detection1995 – Main sequence detection: 51 PegasiLate 1990s – Large number of discoveries due to
advances in technology– CCDs, telescopes, etc.
Detection
Stars outshine their planets– Direct detection is difficult
Need to be clever1. Astrometry
2. Occultation
3. Doppler
4. Microlensing
(Scary names, not so scary ideas)
Detection #1: astrometry
“Star wobble”– Playground connection
• Teeter-Totter & Center of Mass
– Key idea: Objects orbit around the center of mass - even stars!
– Viewed from “above”
– First attempted: 1943
– Not used today: technology
Detection #2: occultation
Who turned off the lights?– Venus transit & lunar
eclipse
What happens on Earth during a lunar eclipse?
Key idea: planets block light from stars
Detection #2: occultation
Detection #3: Doppler
Radial velocity– Doppler effect for sound
• What sound does a speeding ambulance make?
– Radar guns
– Viewed “edge-on”
– Key idea: moving sources appear to change their frequency
Detection #4: microlensing
Einstein– Massive objects bend light.– Some of this (extra) bent
light arrives at Earth.– Causes objects to appear
brighter (more light rays).
– Key idea: objects with mass bend light (toward Earth, perhaps)
– What do one of these look like? And how would a planet affect it?
Detection #4: microlensing
This is not the light form the host star.
Detection: a summary
Astrometry– Star wobble
Occultation– Transit
Doppler effect– Think speeding sirens
Microlensing– Oddness of otherwise smooth light curve
So what do we know?
The present
Today: 160+ known ESPs
June 2005: Gliese 867
Most ESPs are HUGE!– Why is this?
Why are ESPs big
Teeter-totter– BIG
• 1st grader invites friends• 5th grader must move out to balance• 5th grader (sun) farther from center of mass
– CLOSE• Time…• Closer planets move faster
The present: first image
What does tomorrow hold?
The future
TPL: Terrestrial Planet Finder 2014 and 2020 launches Interferometry: directly observe light from a planet Spectroscopy on atmosphere of planet
The future is tomorrow!
Thursday, Oct 6, 4:00pmPhysics/Astro Auditorium: A102
Jian Ge, University of Florida: An All Sky Extrasolar Planet Survey with the Sloan
Telescope Detection between 2008-2020
– Monitor 1,000,000 nearby stars
– Tens of thousands of new ESPs possible
Thank you
Questions?