The Transient Universe: AY 250 Spring 2007 Existing Transient Surveys: Radio I: Pulsars Geoff Bower.
The Transient Universe: AY 250 Spring 2007 Extra Solar Planets Geoff Bower.
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Transcript of The Transient Universe: AY 250 Spring 2007 Extra Solar Planets Geoff Bower.
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