Discovering Extrasolar
Planets: New Developments
Final Class Project
Astronomy 191
Doppler Detection
•  How It Works! - Detects small changes in a star’s
velocity when a star staggers under gravitational pull
from a yet undetected exoplanet
•  HARPS (High Accuracy Radial Velocity Planet
Searcher; a telescope) has helped to so far find 75
exoplanets over the past 5 years
•  Has different programs specifically to look for
exoplanets around solar-like stars and M-dwarfs.
Transit Detection
•  How It Works! – watches the dips in stars
light.
•  When a planet is orbiting around a star
there will be changes in the stars light
when the planet is in front of or behind the
star
Astrometric Detection
•  How It Works! – observes the gravitational tugs
of a host star to and away from earth. In other
words, it looks for stellar wobbles
•  Method has been used for 50 years and is just
now really being used as a viable source to
detect extrasolar planets
•  Recently has discovered the lowest-mass star
to host a planet; something other methods have
not been able to do
Direct Imaging
Visible image of
an extrasolar
planet orbiting a
star
•  How It Works! – method of just looking at stars
using telescopes to detect planets orbiting;
taking pictures instead of inferring from other
methods
•  Visible photography can be used, but infrared
detection is popularly used. Infrared is used to
look for planets particularly around young,
massive, nearby stars.
Kinds of Planets: Excels and Limits
Doppler
Transit
Astrometric
Direct Imaging
Great for
detecting small
planets (mass of
a few times the
earth)
Great for
detecting earthlike planets
Great for
detecting solar
systems like our
own
Does not have to
infer information
like other
methods
Small planets in
multi-planet
systems
Indirect Method
Information
Downfalls- inferred from
parent planets
Earthlike planets
within the
habitable region
of their sun
Indirect Method
Direct Method
Direct Method
Information
inferred from
parent planets
Takes years of
observations to
conclude
May not be able
to detect from
ground viewings
Works Cited
Astronomy Picture of the Day. Web. 01 Dec. 2009. <http://antwrp.gsfc.nasa.gov/apod/astropix.html>.
Beatty, Kelly. "Kepler Shows Its Promise." Sky & Telescope: The Essential Magazine of
Astronomy. Sky Publishing, 7 Aug. 2009. Web. 11 Nov. 2009. <http://www.skyandtelescope.com/community/
skyblog/newsblog/52657352.html>.
European Southern Observatory. "Towards Other Earths: 32 New Exoplanets Found."
ScienceDaily 19 October 2009. 11 November 2009 <http://www.sciencedaily.com-/releases/
2009/10/091019105304.htm>.
Matson, John. "Out of this World Pictures: First Direct Photos of Exoplanets." Scientific
American. Scientific American Inc., 13 Nov. 2009. Web. 11 Nov. 2009. <http://www.scientificamerican.com/
article.cfm?id=exoplanets-directimaging&page=2>.
Naeye, Robert. "At Last, an Exoplanet by Astrometry." Sky & Telescope: The Essential
Magazine of Astronomy.Sky Publishing, 29 May 2009. Web. 11 Nov. 2009.
<http://www.skyandtelescope.com/community/skyblog/newsblog/46462532.html>.
Strobel, Nick. Astronomy Notes. Astronomy Notes.com. 7 Apr. 2009. Web. 11 Nov. 2009.
<http://www.astronomynotes.com/>.
Wolf, Portia. "Extrasolar Planets." The Outer Planets. Laboratory for Atmospheric and
Space Physics. Web. 11 Nov. 2009. <http://lasp.colorado.edu/education/outerplanets/credits.php>.