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 DetectionFirst 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 Analysishttp://archive.stsci.edu/prepds/kepler_hlsp/

Excel graph from Kepler data

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Answershttp://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/animations/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/missions_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/features/gliese_581_feature.html

New Method to Validate Extra solar Planets

http://kepler.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=127

http://www.nasa.gov/topics/universe/features/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 StandardsAstronomy – 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 StandardsEarth 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

• 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 gears@colstate.edu 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