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Bringing E.T. into Your
Classroom
The Search for Extra solar
Planets
Gary Lawhon
Dave Baltenberger
Nebular theory of solar system
formation would lead us to believe
planets should be associated with most
.
stars
Why are these planets so hard to
find?
Planets are really
small
If the Sun is a grapefruit on the West coast of US
then
The Earth is a pinhead about 15 meters away
and Jupiter is a marble 80 meters away
and
The nearest star to our solar system is on the
East coast………….so
You are trying to find a pinhead on a grapefruit
about 2500 miles away plus the star is a billion
times brighter than its planets
How can we find Extra solar
Planets?
Direct Detection
Despite advances in technology it is difficult to find
extra solar planets using direct detection
Direct Detection
First image of an exoplanet?
In July 2004 a group of astronomers led by Gael
Chauvin took this image of a planetary-mass
object in orbit around brown dwarf 2M1207.
Credit: NaCo, VLT, ESO
How can we find Extra solar
Planets?
If we can’t just find these extra solar planets in
a telescope how do we know they exist?
Whiteboard
What other methods could astronomers use to
find extra solar planets?
Does a Planet influence its Star?
All objects in the
solar system orbit
a common center
of mass
Sun is so large that
this center of mass
is inside the Sun
Center of Mass
Orbiting planet causes its star to
“wobble”
http://www.daviddarling.info/encyclopedia/R/radial_velocity_method.html
• Doppler Effect Worksheet
Can We Detect Extrasolar Planets
using other Methods?
Transit method: A planet passing it front of its
star produces a change in brightness of
1/10,000 lasting for 2 to 16 hours
Can we detect that?
Credit: NASA
Kepler mission
The Kepler spacecraft lifted off March 6, 2009
Kepler field of view
http://astro.unl.edu/naap/esp/animations/transitSimulator.html
Based on simulator, which criteria makes it easier
to find planets using the transit method. If it doesn't
matter, write EQUAL CHANCE
1. Less massive stars or more massive stars.
2. Planets with orbits that are closer to circular or
highly elliptical orbits.
3. Face-on orbits or edge-on orbits.
4. Small diameter planets or large diameter
planets.
5. Small mass planets or large mass planets.
6. Planets close to star or planets far from star.
Whiteboard
Based on these observations in the
simulator, what types of planets around
what types of stars would be easier to
find?
Analyze Kepler data
• Download data from Kepler website for
first five extra solar planets found by
Kepler
• Make graph in Excel
• Determine period of planet
• Calculate:
– Distance of planet from star
– Surface temperature of planet
– Radius of planet
Kepler Data Analysis
http://archive.stsci.edu/prepds/kepler_hlsp/
Excel graph from Kepler data
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Answers
http://kepler.nasa.gov/Mission/discoveries/
http://www.planetary.org/exoplanets/list.php?s=kepler
.
http://kepler.nasa.gov/multimedia/Interactives/keplerFlashAdvDiscovery/#
Habitable zone
• Simulator
http://astro.unl.edu/naap/habitablezones/ani
mations/stellarHabitableZone.html
• Discussion
• Biology: silicon / arsenic based life
• Water needed???
Where are we now in search for
extra solar planets?
• http://planetary.org/exoplanets/list.php
• http://kepler.nasa.gov/Mission/discoveries/
• http://planetquest.jpl.nasa.gov/missions/mi
ssions_index.cfm
Kepler Mission
“Follow Up Observing Program”
Program of ground based observations to
confirm that a Kepler planet candidate is
actually a planet
Possible false positive = Binary star system
Kepler Mission
“Follow Up Observing Program”
Detecting False Positives
• Image of star using “adaptive optics” of the
5-meter Palomar telescope and the MMT
telescope on Mt. Hopkins. These high
quality images are able to detect an
eclipsing binary star
Kepler Mission
“Follow Up Observing Program”
Detecting False Positives
• Eclipsing binary stars exhibit two distinct
spectra one on top of the other, but
displaced from each other by the Doppler
Effect.
• An eclipsing binary star would exhibit two
different speed readings in its spectrum of
colors, betraying the existence of two
orbiting stars whizzing around each other.
Kepler Mission
“Follow Up Observing Program”
Doppler Effect used to:
1. Verify a planet candidate by the wobble it
causes on host star
2. Calculate the mass of planet; more
massive planet causes more Doppler shift
3. Density using mass and diameter (from
transit measurement)
Extra Solar planet news
http://www.nasa.gov/topics/universe/feature
s/gliese_581_feature.html
New Method to Validate Extra solar
Planets
http://kepler.nasa.gov/news/index.cfm?Fuse
Action=ShowNews&NewsID=127
http://www.nasa.gov/topics/universe/feature
s/gliese_581_feature.html
planethunters.org
Detecting Extra solar Planets
• Use star wobble to detect planets
– Wobbling star models
• Kepler looks for dimming of the star to
detect presence of extra solar planet
– Use Kepler data to create Excel graphs to
identify pattern of star dimming
– Use websites to recreate hunt for extra solar
planets
GPS Standards
Astronomy – SAST6 – Students will explore connections between cosmic
phenomena and conditions necessary for life.
Physical Science - SPSP9 – Students will investigate the properties of
waves.
f) Explain the Doppler Effect in terms of everyday interactions.
• (Doppler shift of spectral lines & radial velocity)
Biology – SB1 – Students will analyze the nature of relationships between
structures and functions in living cells.
d) Explain the impact of water on life processes.
SB5 – Students will evaluate the role of natural selection in the
development of the theory of evolution.
(concepts of what defines the “habitable zone” can be brought in here)
GPS Standards
Earth Systems – SES1 – Students will investigate the composition and
formation of Earth systems, including Earth’s relationship to the
solar system.
• (habitable zone)
Chemistry
SC3 – Students will use modern atomic theory to explain the
characteristics of atoms.
f) Relate light emission and movement of electrons to element
identification.
(spectroscopy and detection by radial velocity/Doppler shift)
SC4 – Student will use the organization of the Periodic Table to
predict properties of elements.
b) Compare and contrast trends in the chemical and physical
properties of elements and their placement on the Periodic Table.
(concepts of Habitable Zone, carbon-based life vs. thoughts on
silicon-based life. Also water vs. ammonia)
GPS Standards
• Environmental Science – SEV2 – Students will
demonstrate an understanding that the Earth is
one interconnected system.
a) Describe how the abiotic components
(water, air, and energy) affect the biosphere.
(Habitable Zone)
Astronomy Themed Summer Workshops:
Chem., Physics, Phys. Sci. GPS
•
•
•
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•
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High School Teachers Only This Year
Search for Life in the Universe
Sun Earth Connection: Space Weather
Stars: Formation of the Elements
Crash, Bang, Galaxies!
Email [email protected] for information
• http://cheller.phy.georgiasouthern.edu/gears
This workshop funded by NASA Office of Education Grant
NNX09AH83A and supported by the Georgia Department of
Education, Columbus State University, and Georgia Southern
University