Professor Thomas Madigan

The Kepler Missionand

The Search for Exoplanets

Exoplanets: Extra solar planets or planets in orbit around other stars

Prime directive: to find Earth-like planets in the habitable zone of sun-like stars

Sunlike stars:G class, main sequence stars

Motivation: to complete the Copernican Revolution, to find our reflection in the cosmos

Mission Goals:Using the transit method and by taking large

samplings of data, investigate the range and configuration of planetary systems of target stars in the Lyra / Cygnus region of the sky

Determine the percentage of terrestrial and larger planets that are in or near the habitable zone of a wide variety of stars

Estimate how many planets exist in multiple-star systems and, with that, come to a conclusion regarding their sizes, shapes, mass and densities

Habitable Zone:directly linked to a star’s intrinsic luminosity, it is the region around the star where water can exist in a liquid state

For cooler, less luminous stars, it is closer to the star and less extensive

For hotter, more luminous stars, it is further out and more extensive

Solar System Temperatures and Environmental Parameters

Planet Distance (AU) Temperature (K) Notes

Mercury 0.387 633.65

Venus 0.723 463.59

Earth 1.000 394.19 Habitable zone (inner boundary)

1.116 373.14 Water transitions from gas to liquid

Mars 1.523 319.41

Ice Line 2.100 272.02 Habitable zone (outer boundary) - water transitions from liquid to solid

Asteroid Belt 2.800 235.57 Asteroid belt center of mass and semi-major axis of Ceres

Jupiter 5.204 172.80

Saturn 9.582 127.34

Uranus 19.229 89.89

26.200 77.01 Nitrogen transitions from gas to liquid

Neptune 30.103 71.85 Possible liquid nitrogen geysers on Triton

Pluto 39.481 62.74

Why Sun-like stars?

Life expectancy of G-class stars is measured in tens of billions of years

Habitable zone is far enough from the host star where life-inhibiting gravitational tidal-locking won’t occur

The Kepler InstrumentLaunched on March 6th, 2009, Kepler is a 1-meter

class, orbiting visible-light observatory

The Kepler Instrument

Using the transit method and modern, state-of-the-art Photometry, simultaneously monitors the light curves of over 100,000 target stars

Necessary sensitivity and precision: to accurately measure variations in intensity by one part in 10,000 for earth-like planets in the habitable zone of sun-like stars

The Kepler Instrument

The Kepler Instrument

Candidate stellar and planetary systems are confirmed using large, ground-based telescopes

Kitt Peak National Observatory

The 4-Meter Mayall Reflectorat Kitt Peak

The 4-Meter Mayall Reflectorat Kitt Peak

The Transit Method

We can’t visibly “see” the planet so how do we detect its presence?

– measure variations in the star’s intensity as the planet transits the star

– for earth-like planets in the habitable zone of sun-like stars, a sensitivity and accuracy of one part in 10,000 is necessary

The Transit Method

The Transit Method

The Transit Method

We can’t visibly “see” the planet so how do we determine the composition of the atmosphere?

Changes in the star’s spectra as the planet transits the star will reveal the composition of the planet’s atmosphere

Recent Findings

Kepler 22-b2-earth radii “Super Earth”

– 8 times the earh’s mass– 2x the gravity– believed to harbor abundant water

Recent Findings

Kepler 16 and 16-b“Tatooine”-like system