1. The Discovery of… EXOPLANETS
by Kyle Jeter

2. I. Exoplanet Basics
Extrasolar planets,(exoplanets), are planets orbiting stars other than our Sun.
Swiss astronomers Mayor & Queloz discover the first extrasolar planet around the star 51 Pegasi (4 day orbit!)

3. C. Over 2,000 new “exoplanets” have been discovered D
C. Over 2,000 new “exoplanets” have been discovered D. Americans Geoffrey Marcy & Paul Butler discovered many of the first planets incl. 70 Virginis

5. II. Planet-finding Techniques
A. Doppler Method 1. Star “wobbles” due to gravitational tug of planet (Mass can be found) 2. Doppler shift of light from the star is measured, or… 3. ..the star’s movement is measured against the background of stars Ex/ COROT (Dec. 2006)

7. B. Transit Method (eclipse)
1.Intensity of light may dip as a planet
passes in front of its host star
2. Size of planet measured based on this “blink” in the intensity.
3. Combine size from transit method w / mass
from Doppler method to find density
4. Must be lined up, though..
(~1-10% of star systems)

8. Eclipse method

9. 5. KEPLER MISSION (2009) a. Detect transits to find planets
b. Uses a
photometer
c. Has found Earth- sized planets!! (2014)
d. Launch:

11. C. Direct observation 1. Spitzer (2005) 2. “Hot Jupiters” discovered
3. SIM (Space Interferometry Mission)

13. 4. Gemini/Keck take 1st direct pictures
of exoplanetary system!! (2008)
a. 3 planets, MJupiter
b. Host star, HR 8799 – 1.5 Msun
c. System is 130 l.y. away, in Pegasus
5. Hubble directly images 4th exoplanet
a. Host star, Fomalhaut ≈ 16 Lsun
b. Fomalhaut b ≈ 3 Mjupiter
c. 25 l.y. away in Pisces Australis

17. Gleise 581 Solar System

18. 55 Cancri

19. D. Gravitational microlensing
1. Based on Einstein’s theory
2. First used for planets in 2006
3. “Cold” planet, only 5.5 ME, discovered around very distant star
4. 2 planets found simultaneously in (6 total found w/ this method)
5. Must be lined up, though..

20. III. Surprises & the Holy Grail
*1. Large (Jupiter-sized) planets
found very close to their host stars
2. Not many “super-Jupiters” found
(10-70 Mjupiter)
3. Many have very eccentric orbits

22. B. The Holy Grail
1. Astronomers want to discover Earth -like planets 2. First direct spectrograph (2009) a. Looking for water vapor b. Looking for “Free” oxygen c. Looking for Methane, CO2, etc… 3. Terrestrial Planet Finder (20??)

24. Terrestrial Planet Finder (20??)

25. Terrestrial Planet Finder (20??)

26. IV. Kepler Results (150,000 stars)
150,000 stars surveyed
3600 Candidate planets!
45+ in Habitable Zone of parent star
12+ Potential Earth-sized in habitable zone!
Kepler 10b ( )
1. 1st “Rocky” Planet found by Kepler
rEarth / 4.6 ME / .84 day orbit!
F. Kepler-11 system found w/ 6 planets

30. f. Kepler 37 System