EXTRASOLAR PLANETS

This exoplanet orbiting 51 pegasi is being vaporized by its’s parent star

A NEW FIELD TO STUDY Fundamental Astronomy questions

Do other worlds exist? (last 15 years) Is there life on other worlds? (next 15 years)

EXTRASOLAR PLANET

A Planet that orbits a star outside of our solar system

The picture is a drawing of Gliese 581 C (a star in a habitable zone)

EXTRASOLAR SYSTEMS NUMBERS 400 extrasolar

systems 8 terrestial

planets 182 gas giants 77 jupiters 2 neptunes 5 pulsar planets

3 kuiper belts 2 asteroid belts 14 forming solar

systems with newly formed planets

PROPERTIES OF KNOWN EXTRASOLAR SYSTEMS Why are most

exoplanets gas giants that orbit close to the parent star?

Our current detection methods are biased towards finding gas giants close to a star

It is hard to find terrestrial planets

CHALLENGES FOR OBSERVING EXTRASOLAR PLANETS Planets do not produce any light of their

own Planets are very far away Glare from parent stars hide the planets

Closest planets to our solar system have never even been seen (we watch the star)

DECTECTION METHODS Astronomic and Radial Velocity (235

systems) Transit Method (46 systems) Microlensing (6) Pulsar timeing (3)

ASTROMETRIC Measures a stars position in the sky and

observing how it changes over time

Gravitational pull of planet will cause the star to move in a tiny circle

Called “wobbling”

ASTROMETRIC DISPLACEMENT OF THE SUN DUE TO JUPITER

ASTROMETRIC METHOD

PROS CONS

1 telescope can search many stars at a time

Does not work for far away stars

Difficult to detect terrestrial planets which are smaller

SLOW

RADIAL VELOCITY Doppler effect

The change in frequency of a wave as perceived by a moving observer

Move towards (waves bunch up)

Move back (waves spread out )

DOPPLER EFFECT Works for all kinds

of waves (including light)

Instead of pitch changing, color changes

Blue shift (object approaching)

Red Shift (object Receding)

http://www.youtube.com/watch?v=Man9ulEYSgk

http://www.youtube.com/watch?v=imoxDcn2Sgo

RADIAL VELOCITY METHOD Measure the slight changes of a stars

velocity as the star and planet move When the star moves, the doppler shift

of the starlight can be analyzed Bigger the planet, bigger the doppler

shift

RVM

PROS CONS

Can be used for far away stars

Can only observe 1 star at a time

Difficult to detect terrestrial planets

SLOW