Transcript Properties of Multi

Observed Properties of
Multiple - Planet Systems
Properties of
Multi-Planet Systems:
Outline of Talk
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Properties of Single Planets (Review of Last Time)
Theory: Migration & Planets Tug on Planets
Neptune-Mass Planets: First Observations
Multi-Planet Systems: Properties
Mean-Motion Resonances
Formation & Evolution Puzzles
Exoplanet Detection Methods
Proven Techniques # Planetary Systems
Precise Doppler:
 Transits:
 Gravitational lensing:
 Direct Imaging:
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Techniques for the Future
 Astrometry:
Precise Doppler
Kepler
170
8
3?
2?
Review
Last Time
NASA/JPL
178 Giant
Exoplanets
Detected Around Sun-Like Stars
Doppler Detection of
Wobble of Star
orbiting common
center of mass
with planet(s).
Stars Wobble:
Gravitational pull of Planets
Spectrum
of starlight
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Doppler
Effect of
Star Light
Starlight
From Telescope
High Resolution ``Echelle”
Spectrometer
Echelle
Spectrometer
CCD
Echelle
Grating
Collimator
Spectrum of Star:
Doppler Effect
Saturn induces
3 m/s in Sun :
0.001 pixel
Doppler Precision: 1 m/s
v / c ~ 3 x 10-9
Dl / l ~ 3 x 10-9
4096 Pixels
1300 FGKM Nearby Stars
Doppler Precision: 3 m s-1
115 Extrasolar Planets
Three Telescopes
19 Yrs
(6 AU)
Lick
8 Yrs
(4 AU)
Keck
7 Yrs
(3.5 AU)
Anglo-Aus. Tel.
Doppler Precision:
1.0 ms-1
Keck HIRES Upgrade (2004)
1 year
Known Exoplanets
Jan 1996
178
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a = 0 - 5 AU
M sini = 0.05-15 MJUP
Multiple Planets
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Nearly half found by:
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Swiss team
Harvard teams
Texas teams
New Planet
2.96 MJUP
P = 5.3 yr
e = 0.47
New Planet:
P = 1.3 yr
e ~ 0.1
Sub-Saturn Masses: 30 - 100 MEarth
Msini = 32 MEarth
Msini = 37 MEarth
Msini = 57 MEarth
Sub-Saturn Masses:
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Detectable for P < 3 Month
Review
Giant Planets:
Mass Distribution
Detection Limit:
~ 0.2 MJUP @ 1 AU
Rise
toward
low masses
to 1 MSAT
Sub-Saturn?
Semimajor Axis Distribution
Poor
Detectability
Rise
6.5 %
Occurrence
Flat Extrapolation:
D6% of stars have
planets 3 - 20 AU .
Total: 12 %
Prediction:
Reservoir of Jupiters
at 5-20 AU
Log
Models:
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Inward Migration.
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Planets left in place
as disk vanishes .
Future: Gas Giants Orbiting
Beyond 5 AU
G0 V
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Represents 5 %
of Stars
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Orbits:
Circular or
Eccentric?
Orbital Eccentricities
Tidal Circ.:
a < 0.07 AU
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<e>=0.25
<e> = 0.25
Origin of eccent.
controversial .
(But suggestion
later, and talk by
Veras & Armitage)
 Ecc still high
Beyond 2.5 AU
Super-Earths: 1 - 14 MEarth
The Next Domain
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Earth - Uranus:
Gap in Mass: Factor 14
Terrestrial
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SuperEarths
?
Intermediate Masses:
Do they Form?
Or do planet embryos
accrete gas ala Neptune ?
Ice & Gas giants
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If They Form:
- Terr-like: CO2 Atm. ?
- Neptune-like H&He env ?
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Density: 1 or 5 g cm-3 ?
and
life in the universe
Next Frontier:
First Search for Habitable Worlds
Too hot
Temp = 0 - 100 C
Will Need an Extraordinary, New Telescope
To Detect Earth-Like Planets.
NASA . . .
Too cold
NASA’s Effort to:
Discover Earths
Orbiting other Stars
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Kepler:
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SIM:
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First Survey for Earths:
Occurrence rate.
d = 1 kpc, No masses
Finds Nearby (d< 20 pc) Earths:
Measures masses and orbits.
Follow-up: IR disks, Doppler,
Imaging planets (TPF, AO)
Observed Properties of
Multiple - Planet Systems
HD 12661 (G0 V)
Periodogram
P = 5yr
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HD 12661: 2 - Planet Model
RMS=3.4 m/s
2.5 MJ
1.9 MJ
Possible 6:1 Resonance
Weak Interactions
Gozdziewski & Maciejewski,
Lee & Peale
K0V, 1Gy, 16 pc
HD 128311
2:1 Resonance
Inner
Outer
Per (d) 458
918
Msini 2.3
3.1
ecc 0.23
0.22
w
119
212
Pc / Pb = 2.004
Dynamical Resonance
(Laughlin)
Upsilon Andromedae
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First multiple-planet system discovered around
a regular “main sequence” star in 1999. SFSU
Now have ~ 450 Doppler observations with
precision limited by stellar jitter of ~ 7.5m/s
Upsilon And c & d have significant orbital
eccentricities
(e = 0.25 & 0.27 ±0.02)
Orbit Eccentricities change during 1000 years.
What is the origin of these eccentricities?
Mass = 0.62 MJUP
60 Days
0.65
0.70
0.75
0.80
Upsilon Andromedae: Velocity Residuals
D omega
= 48 deg
Circulating
Or Librating?
eC
P
Tp
ecc
w
K Msini a
(d)
(JD-2450000)
(deg) (m/s) (MJUP) (AU)
----------------------------------------------------------------------------4.61712
2.01588 0.028 66.7 68.1 0.66 0.059
241.2
160.4765 0.24 252
55.7 1.97 0.828
1318.4
138.3883 0.28 300
62.2 3.84 2.569
0 ?
.
Upsilon Andromedae:
.
Triple Planet System
e=0.27
.
2 MJUP
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.
0.6 MJUP
e=0.25
0?
.
.
Impulsive
Origin of ecc ?
(Ford, Rasio,
Malhotra)
4 MJup
.
.
.
.
Planet-Planet Scattering:
Impulsive Origin
Of Eccentricites ?
Upsilon Andromeda:
Origin of Eccentricities
Initial Eccentricity = 0
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Gliese 876
Real-Time Mean-Motion Resonance
and first Super Earth:
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Star’s Mass = 0.32 Msun
Two Jupiters in 2:1 res.
GJ 876: Velocities
Two-Planet
Model
Resid
Time
Laughlin et al. 2004
GL 876
2:1 Mean-Motion Resonance
&
Apsidal Lock
Inner Outer
P
30.1 61.0 d
Msini 0.56 1.89 MJ
e
0.27 0.10
w
330 333
o
Resonance Work:
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Laughlin & Chambers
Lissauer & Rivera
Man Hoi Lee & S.Peale
Gliese 876
2:1
Mean Motion
Resonance
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Precession
Period: 9 yr
Man Hoi Lee
Marcy stopped here,
as time ran out.
GJ 876: Velocities
Two-Planet
Model
Laughlin et al. 2004
Velocity Residuals to
2-Planet fit
Period = 1.94 d
Velocity
M sini = 5.9 MEarth
For i = 50 deg,
MPL = 7.5 MEarth
Orbital Phase
Lowest Mass
Exoplanet to date.
3-Planet Fit
Rivera &
Lissauer
Gliese 876
Two Jupiters in 2:1 Resonance
7 1/2 Earth-Mass Planet
7 1/2 Earth-masses
 Excitation of Eccentricity
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Tidal Heating
178
a, MPL, ecc shown
20 multi-planet systems
151 planet-bearing stars
5 Mean-Motion
Resonances:
Gl 876 (2:1)
55 Cnc (3:1)
HD 82943 (2:1)
HD 73526 (2:1)
HD 128311 (2:1)
Proposed M-M Res. :
HD 37124 (5:1 ?)
HD 12661 (6:1 ?)
HD 202206 (6:1 ?)
Compare Multi-Planet
systems to singleplanet systems
Single-Planet Systems
Planet Mass
Distributions
M sini (MJUP)
Ups And
Multi-Planet Systems
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Neptunes
Saturn
Common
Paucity
Explanation?
M sini (MJUP)
Single-Planets
Eccentricities:
No Sig.
Difference;
GJ 876
Multi-Planets
Surprising:
Multi-systems
should suffer
resonances &
perturbations
Summary
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Planet Mass Distribution: Peaks Below 1 MSAT
Semimajor Axis Distrib. Rises toward 5 AU
Multi-planet Systems common
Mean-Motion Resonances Common
Migration, capture, eccentricity pumping
Properties of Multi-Planets not very different
from single-planet systems: Common processes?
Total eccentricity vs Total Planet Mass
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GJ 876
More mass
Higher eccentricity
Planet Mass Ratio
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GJ 876
Period Ratio
Stability of large Mass ratios
Requires wide separation
13
7
GJ 876
Outer planet tends to be more massive.
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GJ 876
Single-Planets
Metalicity
Dependence
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GJ 876
Same for
Single and
Multi-planets:
Multi-Planets
High Fe/H
Favored.
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GJ 876
APF Webcam
The APF Spectrometer
A high resolution spectrometer optimized
for ultra-precision radial velocity work
• Constant gravity environment
• Athermalized optical train
• High efficiency (35%)
l/Dl = 100,000 (for 1 arcsec slit)
• Passively compensated space-frame
• 1 m/s velocity precision
• Cost: $2 million (NASA)
Designed by Steve Vogt
What We've Learned

Giant Planets in Short Period & Eccentric
Orbits
Orbital Migration
 Eccentricity Excitation
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Multiple Planet Systems
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Importance of Resonances
Statistics
Frequency of Giant Planets within ~3 AU
 Mass-Period Distribution Function
 Correlations (Stellar Mass & Metallicity, Other
Planets)
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Artwork courtesy of Sylwia Walerys
New Questions
Why did Jupiter stay…
• At 5 AU?
• In a circular orbit?
Do most giant planets…
• Migrate?
• Have eccentric
orbits?
What limits…
• Migration?
• Eccentricity growth?
Implications for terrestrial planets...
• Formation?
• Habitability?
Artwork courtesy of Sylwia Walerys