SETI in the Kepler era
The Impact of Kepler on the Chances to detect
Extra-terrestrial Life
ILASOL 2011
Amri Wandel, HUJI
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Are we alone?
 The
SETI era: 1960
 Searching
 The

Extra Terrestrial Intelligence
exo-planet boom
What has changed with Kepler?
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How frequent is extra-terrestrial life?
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How many civilizations exist in our Galaxy ?
?
1011 stars
10% Sunlike
Planets in HZ
?
Earthlike
nHZ
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‫‪Planetary disks in Orion‬‬
‫עוברי כוכבים ו”מערכות שמש” בערפילית אוריון‬
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‫‪ILASOL 2011 A. Wandel‬‬
The Doppler method
51 Peg
M Planet Sin (i )  0.47  0.05 M Jup
P  4.229  0.001 days
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The transit method
The inclination must
be very close to 90°
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HD209458
RPlanet  1.35  0.06 RJup
•Planet mass
•Planet radius
• Planet density
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i  86 .7  0 .1
M Planet  0.65M Jup
 .Planet  0.35 g cm 3
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Observatories in Space
CoRoT
Darwin
SIM
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Kepler
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Sensitivity of
exo-planet
projects
 Radial velocity
(Doppler)
 Transit
 Micro-lensing
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The Kepler mission
Search Earthlike exo-planets
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How many civilizations are in the Galaxy ?
1011 stars in MW
10% Sunlike
?Planets in HZ
?? Earthlike
nHZ
fb
Lifetime
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The Drake parameters
R* ~ 10 yr -1 star formation rate in the Galaxy

Fs – fraction of stars suitable for life

Fp – fraction of stars with planets

Fe – fraction of Earthlike planets

np - average # of planets in star’s HZ

Fb - probability for evolution of biology ?

Fi - probability for evol. of intelligence ??

L - average longevity as radio-civilizations ???
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The Drake equation
N= R* x Fs x Fp x FE x nhz x Fb x Fi x L
astronomical factors bio-social factors
RE - formation rate of habitable Earth-like planets
RE = R* x Fs x Fp x FE x nhz
= 10x 0.1 x 1 x 1 x 1 = 1 (optimist)
= 10x 0.1 x 0.1x0.1x 0.1=0.001(pessimist)
N = RE x Fb x Fi x L
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The 3 unknown factors
Fb x Fi x L
1)
2)
3)
Fb – evolution of life (biology) ~1?
Fi – evolution of intelligence (civilization
with radio technology) <<1?
L – average lifetime of communicative
(radio) civilization <10,000 yr?
Example: Fb=100%, Fi=1% L=10,000 yrs
If RE~1
N~1x0.01x10,000= 100
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Earthlike planets rare:
N = 0.001 x Fi x L
Fi
L
1
0. 1
0.01
1000
1
0. 1
0.01
104
10
1
0. 1
100
10
1
105
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Earthlike planets frequent:
N = 1 x Fi x L
Fi
L
1
0. 1
0.01
1000
1000
100
10
104
104
1000
100
105
104
1000
105
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Probability for a
civilization within 100 ly
Log N or Log L/Fic (REFb=1)
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SETI –
Serch of Extra-Terrestrial Intelligence
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SETI
What do we search?
Artificial radio-signals (leakage)
of extra-Terrestrial origin
Why?
We assume other Civilizations use radio
waves for communication like we do
How?
Radio-telescopes- giant dishes and arrays
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Radio-telescope
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The largest radio-teolescope: Arecibo 300m dish
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The SETI chanses
How far can we detect leakage radio
signals?
Arecibo targeted sensitivity – a few ly
Future arrays – tens of light years
If there are 10,000 civilizations in the
Galaxy, the average distance between
neighbor civilizations is ~1000 ly
The probability that one is within 100 ly
from Earth is in that case is ~1%
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We still don’t know if there are
extra-terretrial civilizations..
We don’t even know what are the
chances to detect them…
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..but after one year of Kepler data,
the chances seem much better.
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