NASA’s Kepler mission in a nutshell
• designed to find Earth-analogues (inside the
habitable zone of Sun-like stars)
• Space telescope => continuous obs. / no atmosphere
• using transit method (+ ground-based FU)
• ~160,000 stars over 3.5 - 4 yrs
• 20 -30 ppm precision (Earth-size transit: 85 ppm)
Science P.I.: Bill Borucki NASA / AMES
 Transit Frequency gives us
ORBIT SIZE
 Orbit Size with Star
Temperature tells us if
planet is in habitable zone.
 Transit duration, depth,
gives us PLANET SIZE
 Size and Mass (with a
doppler measurement of
the “wobble”) gives
DENSITY
 Density is clue to
COMPOSITION.
Kepler’s orbit
42(!) CCD detectors
95 megapixels
105 degree2 FOV
Kepler’s in-flight performance:
Kepler’s in-flight performance:
The problem with FALSE POSITIVES:
No planet at all:
1. Background eclipsing binaries
2. Multiple systems with one eclipsing binary
3. Grazing eclipses of binary stars
4. A transit of a MS star in front of a giant star
Wrong planet:
5. Giant planet transits a background MS star
6. Giant planet transits a giant star
Centroid Shift Analysis:
Follow-Up Observation
Program
• Imaging (Standard, AO, Speckle, HST?)
– Removes confusion due to crowding
• Spectroscopy
– Low-Res removes some false positives (e.g., binaries)
– High-Res can measure
mass of some planets
– Upper limit to RV
for small planets
• Transit Observations
– Test for triples
• Combined with tests
from Kepler data
– Occultations
– Centroid motion
McDonald 2.7m
dRV [ cm / s ]
Follow-up Observing Program (FOP):
McDonald Observatory:
Harlan J. Smith 2.7 m Telescope / Tull Coude Spectrograph
2 years of recon spectroscopy of several hundreds of
Kepler candidates (V ~ 11 to 16)
March to November
Hobby-Eberly 9 m Telescope (HET) / HRS
“Super-recons” S/N ~ 100
2010: 65 hours of planet confirmation obs.
>11 candidates (soon to be Kepler planets!)
Reconnaissance Spectroscopy :
Harlan J. Smith
2.7 m Telescope
&
Tull spectrograph
Kepler 7b: The „Styrofoam“ planet
Period: 4.88 d
Mass: 0.433 MJup
Radius: 1.84 RJup
Density: 0.16 g cm–3
Kepler planets confirmed in Texas:
Endl et al. (2011)
Desert et al. (2011)
more to come soon….
The February 2011 Data Release:
•First 4 months of science data
•Light curves for ~ 156,000 stars!
•1200+ planet candidates
Comparison of Kepler
Result with Theory
Lin & Ida ApJ 604 388 2004
From here on, if I say “Kepler Planet”
I mean “Kepler Planet Candidates”.
Rocky planets
Icy planets
Gas Giants
Comparison of Kepler
Result with Theory
Mordasini, Alibert & Benz, A&A 501 1131 2009
Gas Giants
Icy planets
Rocky Planets
Kepler Planet Occurrence Rates
(Howard et al. 2011)
Occurrence rates take into account the actual observed S/N on each star.
Consider only Kepler candidates in the range Kp<15,Teff=4100-6100 and log g = 4.0-4.9.
Estimates are incomplete for planet radii < 2.0 RE.
Get power-law fit of
df ( R)

 kR R
d log R
with k R  2.90.5
and   1.92  0.11
0.4


Kepler Planet Occurrence Rates
(Howard et al. 2011)
Rp (RE)
P < 10 days
P < 50 days
2-4 RE
0.025±0.003
0.130±0.008
4-8 RE
0.005±0.001
0.023±0.003
8-32 RE
0.004±0.001
0.013±0.002
2-32 RE
0.034±0.003
0.165±0.008
The occurrence rate of hot Jupiters in the Kepler field is only 40% that of the solar
neighborhood. Is Kepler sampling the same population of stars as RV surveys?
Kepler Planet Occurrence Rates
(Howard et al. 2011)
Expand the sample to Teff = 36007100. Include only targets for
which photometric noise permits
discovery of planets of 2RE.
The planet occurrence rate for
small planets (2-4 RE) rises
dramatically with decreasing Teff.

f

T  5100K 
eff

 0.165  0.081
 1000K



T 
eff
Kepler Multi-Planet System
Statistics
Kepler Singles
Kepler Multiples
CoRoT Singles

Latham et al. ApJL in press 2011
Kepler finds very few
giant planets in systems
of multiple planets
Preliminary evidence indicates that up to
30% of stars may have closely packed
planetary systems of superearths
1.
Planets smaller than Neptune dominate
single and multiple transiting systems, but
more so for multiples (68% for singles but
86% for multiples)
2.
Singles may be more common around
hotter stars (i.e. more massive)
Kepler Multi-Planet System
Architectures

Lissauer et al. ApJ submitted 2011
Kepler Multi-Planet System
Architectures
Candidates per system
MMR
Total
Pairs
Adjacent Pairs
2:1
90
74
0
160890
1
776
2
115
3:2
24
21
3
45
4:3
7
5
4
8
5:4
3
2
5
1
3:1
80
54
1 
5:3
15
11
7:5
5
5
9:7
3
3
6 or more
Total stars
Total planets
Total stars with planets
161836
1184
946
Kepler-10b
R = 1.4 Rearth
Period = 0.83 d
Transit Depth:
0.00015
Batalha et al. 2011
Kepler-10b
Batalha et al. 2011
CoRoT-7b
Kepler-10b
r(gm/cm3)
10
7
Earth
Mercury
5
4
3
Venus
Mars
Moon
2
From Diana Valencia
1
0.2
0.4
0.6
0.8
1
1.2
Radius (REarth)
1.4
1.6
1.8
2
CoRoT-7b
Mstar = 0.91 ±0.03 Msun
Rstar = 0.82 ±0.04 Rsun
MPl = 7.3 ±1.35 MEarth
RPl = 1.58 ±0.10 REarth
rPl = 10.2 ±2.7 cgs
Kepler-10b
Mstar = 0.895 ± 0.06 Msun
Rstar = 1.056 ±0.02 Rsun
MPl = 4.56 ±1.23 MEarth
RPl = 1.416 ±0.025 REarth
rPl = 8.8 ±2.5 cgs
Kepler-11
Lissauer et al. 2011
The mutual gravitational
influence of the planets
causes transit timing
variations (TTVS): the
transit of an individual
planet occurs at slightly
different times than
expected. From these
TTVs one can model the
dynamics of the system
and determine the planet
mass. This is the first
system whose planets
masses were determined
without Doppler
measurements.
Kepler-11 planet properties
Summary
Current status:
• Kepler has released Q0-Q2 lightcurves on 155,453 stars
and on the 1,235 planet candidates that it has
discovered in the first four months of science operations.
• The planetary candidates include 68 of Earth-size, 288
of super-Earth-size, 662 of Neptune-size, and 165 of
Jupiter-size.
• 170 stars show the presence of systems of transiting
planetary candidates.
• Kepler continues to make excellent progress toward its
goal of determining the frequency of Earth-size planets.