Www.astro.washington.edu/observatory/ Extra-Solar Planets Theodore Jacobson Observatory University of Washington Brian Stephanik October 5 th, 2005.

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?