Presented at the Astronomy Club of Augusta meeting
at Augusta State University
on July 22, 2005
I. What are Exoplanets?
Exoplanets are planets that
have been found around stars other than the sun.
There are currently 161 Exoplanets
around 137 stars known.
II. Ways to
Pulsar timing uses anomaly
in timing in the pulsing of pulsars to find companions
This method was the first to
Astrometry tries to detect
an occolation in the proper motion of a star.
Astrometry is the first
method used to try to find planets.
Due to limitations of
current equipment, no planets have been found by astrometry.
Radial velocity uses the
Doppler effect to look for a planets pull on a star.
This method is the one that
has found the most planets.
uses gravitys affect on light to find planets.
main advantage is that it can detect Earth sized planets, however it only
happens by chance and can not be repeated.
The transit method uses the
dimming of star by planets going in front of it.
Circumstellar disks are dust
clouds around a star which a planet can distort.
This method requires space
telescopes since the atmosphere absorbs most of the light from the dust clouds.
Direct observation tries to
see a planet directly.
The stars light usually far
outshines the planet.
There may be two planets
found by this method.
III. Future of
There are three missions to
look for exoplanets in the future.
Space Interferometry Mission
Terrestrial Planet Finder
The Space Interometry
Mission will use optical interometry to exactly measure the proper motion of a
This should be exact enough
to find planets by astrometry.
The Terrestrial Planet
Finder is a NASA proposal to find planets
There are two
architectures: multiple telescopes in
formation to cancel out the light from the star and one big telescope with
special optics to decrease the light from the star.
Darwin is a proposal
European Space Agency mission that will use six 1.5 meter telescopes in
formation to cancel out the light from a star.
This is like part of the
Terrestrial Planet Finder and the two projects may merge.
Aleksander Wolszczan found
the first exoplanet around the pulsar PSR 1257+12.
An exoplanet was found in an
unknown galaxy by microlensing the quasar Q0957+561.
Its mass is 3 Earths.
In 2001 the planet HD
209458bs atmosphere was measured by the Hubble.
The atmosphere has hydrogen,
carbon, oxygen, and sodium.
In 2001, a star was found
that had the remnants of planets in its atmosphere.
The oldest planet found is
13 billion years old and is in the M4 star cluster.