The Transient Universe: AY 250 Spring 2007

Extra Solar Planets

Geoff Bower

The Transient Universe: AY 250 Spring 2007

Radial Velocity Detection of Exoplanets

The Transient Universe: AY 250 Spring 2007

Exoplanet Statistics from Radial Velocity Variations

The Transient Universe: AY 250 Spring 2007

Transits

HD 209458Henry et al 1999

The Transient Universe: AY 250 Spring 2007

The Transient Universe: AY 250 Spring 2007

The Transient Universe: AY 250 Spring 2007

Requirements for Transit Detection of Earth

• Photometric sensitivity ~ 10^-5

• Nstars >> 10^3

• Time resolution ~ hours

• Duration ~ years

• Continuous viewing

The Transient Universe: AY 250 Spring 2007

TrESTransiting Extrasolar Planet Search• 3 x 10 cm telescopes• 6 x 6 deg FOV• V< 16 mag• 0.005 mag in 10

minutes

The Transient Universe: AY 250 Spring 2007

TrES-2 Planet in Kepler Field

T=2.5 daysM=1.3 MJupR=1.2 MJupO’Donovan et al 2006

The Transient Universe: AY 250 Spring 2007

All Transiting Planets

Charbonneau et al 2006

The Transient Universe: AY 250 Spring 2007

TreS-1

HD 209458

Star spot causes bump

The Transient Universe: AY 250 Spring 2007

Scintillation Noise

TrESDunham et al 2004

Dravins et al 1997

< 1sec

The Transient Universe: AY 250 Spring 2007

Kepler

The Transient Universe: AY 250 Spring 2007

Kepler Observing Program

• 4 years• Continuous observing• 100 square degrees• 1.4m mirror/0.95 m

corrector• 2” pixels• 42 x 1024 x 2200

pixels• Photometry for

100,00 stars

The Transient Universe: AY 250 Spring 2007

Photometry for 100,000 Stars

• Subset of pixels selected from photometry

• Integrated for 15 minutes

• Smaller subset with 1 minute integrations10^7 measurements/day x ~10-100

pixels/star GB/day

The Transient Universe: AY 250 Spring 2007

• Poisson Noise ~ 1/sqrt(Nphotons)

• Poisson noise sets mirror size

• Stellar variability is the big unknown and factor to be controlled

The Transient Universe: AY 250 Spring 2007

Basri et al 2005

450,000 stars brighter than 15th mag

The Transient Universe: AY 250 Spring 2007

Most Stars Are Inactive

The Transient Universe: AY 250 Spring 2007

Solar Variability

The Transient Universe: AY 250 Spring 2007

Hall et al 2007

The Transient Universe: AY 250 Spring 2007

Stellar Variability

The Transient Universe: AY 250 Spring 2007

Variability Limits on Planet Size

The Transient Universe: AY 250 Spring 2007

Simulated Transit

Matched filter search

The Transient Universe: AY 250 Spring 2007

Semi-major axis

1500 Earth mass planets detected in first year4500 in four yearsAssuming 3 terrestrial planets/star

The Transient Universe: AY 250 Spring 2007

Planet Detection Validation

• 7 sigma detection (total) in >=4 transits

• Period constant to 10 ppm from at least 3 transits

• Duration, depth, shape consistent

• Star centroid the same in and out of transit– Reject background eclipsing star

• Radial velocity follow-up consistent

• High resolution imaging